SERVER-36473 Make a dedicated RAII class to manage Client lifetime

33 files changed, 259 insertions, 229 deletions

diff --git a/src/mongo/db/SConscript b/src/mongo/db/SConscript
index 2737954e8f0..28f2d3c1a43 100644
--- a/src/mongo/db/SConscript
+++ b/src/mongo/db/SConscript
@@ -525,6 +525,20 @@ env.Library(
     ],
 )
 
+env.CppUnitTest(
+    target= 'thread_client_test',
+    source= 'thread_client_test.cpp',
+    LIBDEPS=[
+        'common',
+    ],
+    LIBDEPS_PRIVATE=[
+        'service_context_test_fixture',
+        '$BUILD_DIR/mongo/transport/transport_layer_common',
+        '$BUILD_DIR/mongo/transport/transport_layer_mock',
+        '$BUILD_DIR/mongo/unittest/unittest',
+    ],
+)
+
 env.Library(
     target='lasterror',
     source=[
diff --git a/src/mongo/db/client.cpp b/src/mongo/db/client.cpp
index 1ac7d548bd2..da08647395b 100644
--- a/src/mongo/db/client.cpp
+++ b/src/mongo/db/client.cpp
@@ -88,11 +88,6 @@ void Client::initThread(StringData desc,
     currentClient = service->makeClient(fullDesc, std::move(session));
 }
 
-void Client::destroy() {
-    invariant(haveClient());
-    currentClient.reset(nullptr);
-}
-
 namespace {
 int64_t generateSeed(const std::string& desc) {
     size_t seed = 0;
@@ -169,4 +164,19 @@ void Client::setCurrent(ServiceContext::UniqueClient client) {
     currentClient = std::move(client);
 }
 
+ThreadClient::ThreadClient(ServiceContext* serviceContext)
+    : ThreadClient(getThreadName(), serviceContext, nullptr) {}
+
+ThreadClient::ThreadClient(StringData desc,
+                           ServiceContext* serviceContext,
+                           transport::SessionHandle session) {
+    invariant(!currentClient);
+    Client::initThread(desc, serviceContext, std::move(session));
+}
+
+ThreadClient::~ThreadClient() {
+    invariant(currentClient);
+    currentClient.reset(nullptr);
+}
+
 }  // namespace mongo
diff --git a/src/mongo/db/client.h b/src/mongo/db/client.h
index 0393adf46f3..75eabd72f09 100644
--- a/src/mongo/db/client.h
+++ b/src/mongo/db/client.h
@@ -55,6 +55,7 @@ namespace mongo {
 
 class Collection;
 class OperationContext;
+class ThreadClient;
 
 typedef long long ConnectionId;
 
@@ -78,8 +79,8 @@ public:
 
     /**
      * Moves client into the thread_local for this thread. After this call, Client::getCurrent
-     * and cc() will return client.get(). The client will be destroyed with the thread exits
-     * or Client::destroy() is called.
+     * and cc() will return client.get(). The client will be destroyed when the thread exits
+     * or the ThreadClient RAII helper exits its scope.
      */
     static void setCurrent(ServiceContext::UniqueClient client);
 
@@ -139,15 +140,6 @@ public:
      */
     static void initThreadIfNotAlready();
 
-    /**
-     * Destroys the Client object stored in TLS for the current thread. The current thread must have
-     * a Client.
-     *
-     * If destroy() is not called explicitly, then the Client stored in TLS will be destroyed upon
-     * exit of the current thread.
-     */
-    static void destroy();
-
     std::string clientAddress(bool includePort = false) const;
     const std::string& desc() const {
         return _desc;
@@ -219,6 +211,7 @@ public:
 
 private:
     friend class ServiceContext;
+    friend class ThreadClient;
     explicit Client(std::string desc,
                     ServiceContext* serviceContext,
                     transport::SessionHandle session);
@@ -245,6 +238,29 @@ private:
 };
 
 /**
+ * RAII-style Client helper to manage its lifecycle.
+ * Instantiates a client on the current thread, which remains bound to this thread so long as the
+ * instance of ThreadClient is in scope.
+ *
+ * Swapping the managed Client by ThreadClient with AlternativeClientRegion is permitted so long as
+ * the AlternativeClientRegion is not used beyond the scope of ThreadClient.
+ *
+ * Calling Client::releaseCurrent() is not permitted on a Client managed by the ThreadClient and
+ * will invariant once ThreadClient goes out of scope.
+ */
+class ThreadClient {
+public:
+    explicit ThreadClient(ServiceContext* serviceContext);
+    explicit ThreadClient(StringData desc,
+                          ServiceContext* serviceContext,
+                          transport::SessionHandle session = nullptr);
+    ~ThreadClient();
+    ThreadClient(const ThreadClient&) = delete;
+    ThreadClient(ThreadClient&&) = delete;
+    void operator=(const ThreadClient&) = delete;
+};
+
+/**
  * Utility class to temporarily swap which client is bound to the running thread.
  *
  * Use this class to bind a client to the current thread for the duration of the
diff --git a/src/mongo/db/clientcursor.cpp b/src/mongo/db/clientcursor.cpp
index 68d8d790d59..8c489cb3b8e 100644
--- a/src/mongo/db/clientcursor.cpp
+++ b/src/mongo/db/clientcursor.cpp
@@ -286,8 +286,7 @@ public:
     }
 
     void run() {
-        Client::initThread("clientcursormon");
-        ON_BLOCK_EXIT([] { Client::destroy(); });
+        ThreadClient tc("clientcursormon", getGlobalServiceContext());
         while (!globalInShutdownDeprecated()) {
             {
                 const ServiceContext::UniqueOperationContext opCtx = cc().makeOperationContext();
diff --git a/src/mongo/db/commands/dbcheck.cpp b/src/mongo/db/commands/dbcheck.cpp
index 44dcddc3ff6..fa6e107ba00 100644
--- a/src/mongo/db/commands/dbcheck.cpp
+++ b/src/mongo/db/commands/dbcheck.cpp
@@ -193,8 +193,7 @@ protected:
 
     virtual void run() override {
         // Every dbCheck runs in its own client.
-        Client::initThread(name());
-        ON_BLOCK_EXIT([] { Client::destroy(); });
+        ThreadClient tc(name(), getGlobalServiceContext());
 
         for (const auto& coll : *_run) {
             try {
diff --git a/src/mongo/db/commands/fsync.cpp b/src/mongo/db/commands/fsync.cpp
index 2043779e567..51ad036348c 100644
--- a/src/mongo/db/commands/fsync.cpp
+++ b/src/mongo/db/commands/fsync.cpp
@@ -332,8 +332,7 @@ private:
 SimpleMutex filesLockedFsync;
 
 void FSyncLockThread::run() {
-    Client::initThread("fsyncLockWorker");
-    ON_BLOCK_EXIT([] { Client::destroy(); });
+    ThreadClient tc("fsyncLockWorker", getGlobalServiceContext());
     stdx::lock_guard<SimpleMutex> lkf(filesLockedFsync);
     stdx::unique_lock<stdx::mutex> lk(fsyncCmd.lockStateMutex);
 
diff --git a/src/mongo/db/index_builder.cpp b/src/mongo/db/index_builder.cpp
index a95b20674f7..dde059c7254 100644
--- a/src/mongo/db/index_builder.cpp
+++ b/src/mongo/db/index_builder.cpp
@@ -120,8 +120,7 @@ std::string IndexBuilder::name() const {
 }
 
 void IndexBuilder::run() {
-    Client::initThread(name().c_str());
-    ON_BLOCK_EXIT([] { Client::destroy(); });
+    ThreadClient tc(name(), getGlobalServiceContext());
     LOG(2) << "IndexBuilder building index " << _index;
 
     auto opCtx = cc().makeOperationContext();
diff --git a/src/mongo/db/repl/initial_syncer_test.cpp b/src/mongo/db/repl/initial_syncer_test.cpp
index 8e27e960931..6bc02d4d15a 100644
--- a/src/mongo/db/repl/initial_syncer_test.cpp
+++ b/src/mongo/db/repl/initial_syncer_test.cpp
@@ -120,7 +120,7 @@ class InitialSyncerTest : public executor::ThreadPoolExecutorTest,
                           public SyncSourceSelector,
                           public ScopedGlobalServiceContextForTest {
 public:
-    InitialSyncerTest() {}
+    InitialSyncerTest() : _threadClient(getGlobalServiceContext()) {}
 
     executor::ThreadPoolMock::Options makeThreadPoolMockOptions() const override;
 
@@ -331,7 +331,6 @@ protected:
         _mockServer = stdx::make_unique<MockRemoteDBServer>(_target.toString());
         _options1.uuid = UUID::gen();
 
-        Client::initThreadIfNotAlready();
         reset();
 
         launchExecutorThread();
@@ -435,7 +434,6 @@ protected:
         _dbWorkThreadPool.reset();
         _replicationProcess.reset();
         _storageInterface.reset();
-        Client::destroy();
     }
 
     /**
@@ -481,6 +479,7 @@ protected:
 private:
     DataReplicatorExternalStateMock* _externalState;
     std::unique_ptr<InitialSyncer> _initialSyncer;
+    ThreadClient _threadClient;
     bool _executorThreadShutdownComplete = false;
 };
 
diff --git a/src/mongo/db/s/balancer/migration_manager.cpp b/src/mongo/db/s/balancer/migration_manager.cpp
index 80b227adfbf..4af83add8e2 100644
--- a/src/mongo/db/s/balancer/migration_manager.cpp
+++ b/src/mongo/db/s/balancer/migration_manager.cpp
@@ -521,8 +521,7 @@ void MigrationManager::_schedule(WithLock lock,
         executor->scheduleRemoteCommand(
             remoteRequest,
             [this, itMigration](const executor::TaskExecutor::RemoteCommandCallbackArgs& args) {
-                Client::initThread(getThreadName());
-                ON_BLOCK_EXIT([&] { Client::destroy(); });
+                ThreadClient tc(getThreadName(), getGlobalServiceContext());
                 auto opCtx = cc().makeOperationContext();
 
                 stdx::lock_guard<stdx::mutex> lock(_mutex);
diff --git a/src/mongo/db/s/balancer/migration_manager_test.cpp b/src/mongo/db/s/balancer/migration_manager_test.cpp
index c9d218f4b07..c9efb7923d3 100644
--- a/src/mongo/db/s/balancer/migration_manager_test.cpp
+++ b/src/mongo/db/s/balancer/migration_manager_test.cpp
@@ -311,8 +311,7 @@ TEST_F(MigrationManagerTest, OneCollectionTwoMigrations) {
     const std::vector<MigrateInfo> migrationRequests{{kShardId1, chunk1}, {kShardId3, chunk2}};
 
     auto future = launchAsync([this, migrationRequests] {
-        ON_BLOCK_EXIT([&] { Client::destroy(); });
-        Client::initThreadIfNotAlready("Test");
+        ThreadClient tc("Test", getGlobalServiceContext());
         auto opCtx = cc().makeOperationContext();
 
         // Scheduling the moveChunk commands requires finding a host to which to send the command.
@@ -374,8 +373,7 @@ TEST_F(MigrationManagerTest, TwoCollectionsTwoMigrationsEach) {
                                                      {kShardId3, chunk2coll2}};
 
     auto future = launchAsync([this, migrationRequests] {
-        ON_BLOCK_EXIT([&] { Client::destroy(); });
-        Client::initThreadIfNotAlready("Test");
+        ThreadClient tc("Test", getGlobalServiceContext());
         auto opCtx = cc().makeOperationContext();
 
         // Scheduling the moveChunk commands requires finding a host to which to send the command.
@@ -429,8 +427,7 @@ TEST_F(MigrationManagerTest, SourceShardNotFound) {
     const std::vector<MigrateInfo> migrationRequests{{kShardId1, chunk1}, {kShardId3, chunk2}};
 
     auto future = launchAsync([this, chunk1, chunk2, migrationRequests] {
-        ON_BLOCK_EXIT([&] { Client::destroy(); });
-        Client::initThreadIfNotAlready("Test");
+        ThreadClient tc("Test", getGlobalServiceContext());
         auto opCtx = cc().makeOperationContext();
 
         // Scheduling a moveChunk command requires finding a host to which to send the command. Set
@@ -476,8 +473,7 @@ TEST_F(MigrationManagerTest, JumboChunkResponseBackwardsCompatibility) {
     const std::vector<MigrateInfo> migrationRequests{{kShardId1, chunk1}};
 
     auto future = launchAsync([this, chunk1, migrationRequests] {
-        ON_BLOCK_EXIT([&] { Client::destroy(); });
-        Client::initThreadIfNotAlready("Test");
+        ThreadClient tc("Test", getGlobalServiceContext());
         auto opCtx = cc().makeOperationContext();
 
         // Scheduling a moveChunk command requires finding a host to which to send the command. Set
@@ -515,8 +511,7 @@ TEST_F(MigrationManagerTest, InterruptMigration) {
         setUpChunk(collName, kKeyPattern.globalMin(), kKeyPattern.globalMax(), kShardId0, version);
 
     auto future = launchAsync([&] {
-        ON_BLOCK_EXIT([&] { Client::destroy(); });
-        Client::initThreadIfNotAlready("Test");
+        ThreadClient tc("Test", getGlobalServiceContext());
         auto opCtx = cc().makeOperationContext();
 
         // Scheduling a moveChunk command requires finding a host to which to send the command. Set
@@ -604,8 +599,7 @@ TEST_F(MigrationManagerTest, RestartMigrationManager) {
     _migrationManager->finishRecovery(operationContext(), 0, kDefaultSecondaryThrottle);
 
     auto future = launchAsync([&] {
-        ON_BLOCK_EXIT([&] { Client::destroy(); });
-        Client::initThreadIfNotAlready("Test");
+        ThreadClient tc("Test", getGlobalServiceContext());
         auto opCtx = cc().makeOperationContext();
 
         // Scheduling a moveChunk command requires finding a host to which to send the command. Set
@@ -659,8 +653,7 @@ TEST_F(MigrationManagerTest, MigrationRecovery) {
     _migrationManager->startRecoveryAndAcquireDistLocks(operationContext());
 
     auto future = launchAsync([this] {
-        ON_BLOCK_EXIT([&] { Client::destroy(); });
-        Client::initThreadIfNotAlready("Test");
+        ThreadClient tc("Test", getGlobalServiceContext());
         auto opCtx = cc().makeOperationContext();
 
         // Scheduling the moveChunk commands requires finding hosts to which to send the commands.
@@ -761,8 +754,7 @@ TEST_F(MigrationManagerTest, RemoteCallErrorConversionToOperationFailed) {
         setUpChunk(collName, BSON(kPattern << 49), kKeyPattern.globalMax(), kShardId2, version);
 
     auto future = launchAsync([&] {
-        ON_BLOCK_EXIT([&] { Client::destroy(); });
-        Client::initThreadIfNotAlready("Test");
+        ThreadClient tc("Test", getGlobalServiceContext());
         auto opCtx = cc().makeOperationContext();
 
         // Scheduling the moveChunk commands requires finding a host to which to send the command.
diff --git a/src/mongo/db/s/config/sharding_catalog_manager_add_shard_test.cpp b/src/mongo/db/s/config/sharding_catalog_manager_add_shard_test.cpp
index 7004fb1ebc3..73095f7aed4 100644
--- a/src/mongo/db/s/config/sharding_catalog_manager_add_shard_test.cpp
+++ b/src/mongo/db/s/config/sharding_catalog_manager_add_shard_test.cpp
@@ -407,8 +407,7 @@ TEST_F(AddShardTest, StandaloneBasicSuccess) {
     operationContext()->setWriteConcern(ShardingCatalogClient::kMajorityWriteConcern);
 
     auto future = launchAsync([this, expectedShardName] {
-        ON_BLOCK_EXIT([&] { Client::destroy(); });
-        Client::initThreadIfNotAlready();
+        ThreadClient tc(getGlobalServiceContext());
         auto shardName =
             assertGet(ShardingCatalogManager::get(operationContext())
                           ->addShard(operationContext(),
@@ -492,8 +491,7 @@ TEST_F(AddShardTest, StandaloneGenerateName) {
         "TestDB2", ShardId(expectedShardName), false, databaseVersion::makeNew());
 
     auto future = launchAsync([this, &expectedShardName, &shardTarget] {
-        ON_BLOCK_EXIT([&] { Client::destroy(); });
-        Client::initThreadIfNotAlready();
+        ThreadClient tc(getGlobalServiceContext());
         auto shardName = assertGet(
             ShardingCatalogManager::get(operationContext())
                 ->addShard(operationContext(), nullptr, ConnectionString(shardTarget), 100));
@@ -584,8 +582,7 @@ TEST_F(AddShardTest, UnreachableHost) {
     std::string expectedShardName = "StandaloneShard";
 
     auto future = launchAsync([this, &expectedShardName, &shardTarget] {
-        ON_BLOCK_EXIT([&] { Client::destroy(); });
-        Client::initThreadIfNotAlready();
+        ThreadClient tc(getGlobalServiceContext());
         auto status =
             ShardingCatalogManager::get(operationContext())
                 ->addShard(
@@ -612,8 +609,7 @@ TEST_F(AddShardTest, AddMongosAsShard) {
     std::string expectedShardName = "StandaloneShard";
 
     auto future = launchAsync([this, &expectedShardName, &shardTarget] {
-        ON_BLOCK_EXIT([&] { Client::destroy(); });
-        Client::initThreadIfNotAlready();
+        ThreadClient tc(getGlobalServiceContext());
         auto status =
             ShardingCatalogManager::get(operationContext())
                 ->addShard(
@@ -640,8 +636,7 @@ TEST_F(AddShardTest, AddReplicaSetShardAsStandalone) {
     std::string expectedShardName = "Standalone";
 
     auto future = launchAsync([this, expectedShardName, shardTarget] {
-        ON_BLOCK_EXIT([&] { Client::destroy(); });
-        Client::initThreadIfNotAlready();
+        ThreadClient tc(getGlobalServiceContext());
         auto status =
             ShardingCatalogManager::get(operationContext())
                 ->addShard(
@@ -673,8 +668,7 @@ TEST_F(AddShardTest, AddStandaloneHostShardAsReplicaSet) {
     std::string expectedShardName = "StandaloneShard";
 
     auto future = launchAsync([this, expectedShardName, connString] {
-        ON_BLOCK_EXIT([&] { Client::destroy(); });
-        Client::initThreadIfNotAlready();
+        ThreadClient tc(getGlobalServiceContext());
         auto status = ShardingCatalogManager::get(operationContext())
                           ->addShard(operationContext(), &expectedShardName, connString, 100);
         ASSERT_EQUALS(ErrorCodes::OperationFailed, status);
@@ -702,8 +696,7 @@ TEST_F(AddShardTest, ReplicaSetMistmatchedReplicaSetName) {
     std::string expectedShardName = "StandaloneShard";
 
     auto future = launchAsync([this, expectedShardName, connString] {
-        ON_BLOCK_EXIT([&] { Client::destroy(); });
-        Client::initThreadIfNotAlready();
+        ThreadClient tc(getGlobalServiceContext());
         auto status = ShardingCatalogManager::get(operationContext())
                           ->addShard(operationContext(), &expectedShardName, connString, 100);
         ASSERT_EQUALS(ErrorCodes::OperationFailed, status);
@@ -733,8 +726,7 @@ TEST_F(AddShardTest, ShardIsCSRSConfigServer) {
     std::string expectedShardName = "StandaloneShard";
 
     auto future = launchAsync([this, expectedShardName, connString] {
-        ON_BLOCK_EXIT([&] { Client::destroy(); });
-        Client::initThreadIfNotAlready();
+        ThreadClient tc(getGlobalServiceContext());
         auto status = ShardingCatalogManager::get(operationContext())
                           ->addShard(operationContext(), &expectedShardName, connString, 100);
         ASSERT_EQUALS(ErrorCodes::OperationFailed, status);
@@ -767,8 +759,7 @@ TEST_F(AddShardTest, ReplicaSetMissingHostsProvidedInSeedList) {
     std::string expectedShardName = "StandaloneShard";
 
     auto future = launchAsync([this, expectedShardName, connString] {
-        ON_BLOCK_EXIT([&] { Client::destroy(); });
-        Client::initThreadIfNotAlready();
+        ThreadClient tc(getGlobalServiceContext());
         auto status = ShardingCatalogManager::get(operationContext())
                           ->addShard(operationContext(), &expectedShardName, connString, 100);
         ASSERT_EQUALS(ErrorCodes::OperationFailed, status);
@@ -803,8 +794,7 @@ TEST_F(AddShardTest, AddShardWithNameConfigFails) {
     std::string expectedShardName = "config";
 
     auto future = launchAsync([this, expectedShardName, connString] {
-        ON_BLOCK_EXIT([&] { Client::destroy(); });
-        Client::initThreadIfNotAlready();
+        ThreadClient tc(getGlobalServiceContext());
         auto status = ShardingCatalogManager::get(operationContext())
                           ->addShard(operationContext(), &expectedShardName, connString, 100);
         ASSERT_EQUALS(ErrorCodes::BadValue, status);
@@ -850,8 +840,7 @@ TEST_F(AddShardTest, ShardContainsExistingDatabase) {
 
 
     auto future = launchAsync([this, expectedShardName, connString] {
-        ON_BLOCK_EXIT([&] { Client::destroy(); });
-        Client::initThreadIfNotAlready();
+        ThreadClient tc(getGlobalServiceContext());
         auto status = ShardingCatalogManager::get(operationContext())
                           ->addShard(operationContext(), &expectedShardName, connString, 100);
         ASSERT_EQUALS(ErrorCodes::OperationFailed, status);
@@ -899,8 +888,7 @@ TEST_F(AddShardTest, SuccessfullyAddReplicaSet) {
         "shardDB", ShardId(expectedShardName), false, databaseVersion::makeNew());
 
     auto future = launchAsync([this, &expectedShardName, &connString] {
-        ON_BLOCK_EXIT([&] { Client::destroy(); });
-        Client::initThreadIfNotAlready();
+        ThreadClient tc(getGlobalServiceContext());
         auto shardName = assertGet(ShardingCatalogManager::get(operationContext())
                                        ->addShard(operationContext(), nullptr, connString, 100));
         ASSERT_EQUALS(expectedShardName, shardName);
@@ -966,8 +954,7 @@ TEST_F(AddShardTest, ReplicaSetExtraHostsDiscovered) {
         "shardDB", ShardId(expectedShardName), false, databaseVersion::makeNew());
 
     auto future = launchAsync([this, &expectedShardName, &seedString] {
-        ON_BLOCK_EXIT([&] { Client::destroy(); });
-        Client::initThreadIfNotAlready();
+        ThreadClient tc(getGlobalServiceContext());
         auto shardName = assertGet(ShardingCatalogManager::get(operationContext())
                                        ->addShard(operationContext(), nullptr, seedString, 100));
         ASSERT_EQUALS(expectedShardName, shardName);
@@ -1044,8 +1031,7 @@ TEST_F(AddShardTest, AddShardSucceedsEvenIfAddingDBsFromNewShardFails) {
     ON_BLOCK_EXIT([&] { failPoint->setMode(FailPoint::off); });
 
     auto future = launchAsync([this, &expectedShardName, &shardTarget] {
-        ON_BLOCK_EXIT([&] { Client::destroy(); });
-        Client::initThreadIfNotAlready();
+        ThreadClient tc(getGlobalServiceContext());
         auto shardName = assertGet(
             ShardingCatalogManager::get(operationContext())
                 ->addShard(
@@ -1136,8 +1122,7 @@ TEST_F(AddShardTest, AddExistingShardStandalone) {
     // Adding the same standalone host with a different shard name should fail.
     std::string differentName = "anotherShardName";
     auto future1 = launchAsync([&] {
-        ON_BLOCK_EXIT([&] { Client::destroy(); });
-        Client::initThreadIfNotAlready();
+        ThreadClient tc(getGlobalServiceContext());
         ASSERT_EQUALS(ErrorCodes::IllegalOperation,
                       ShardingCatalogManager::get(operationContext())
                           ->addShard(operationContext(),
@@ -1152,8 +1137,7 @@ TEST_F(AddShardTest, AddExistingShardStandalone) {
 
     // Adding the same standalone host with a different maxSize should fail.
     auto future2 = launchAsync([&] {
-        ON_BLOCK_EXIT([&] { Client::destroy(); });
-        Client::initThreadIfNotAlready();
+        ThreadClient tc(getGlobalServiceContext());
         ASSERT_EQUALS(ErrorCodes::IllegalOperation,
                       ShardingCatalogManager::get(operationContext())
                           ->addShard(operationContext(),
@@ -1168,8 +1152,7 @@ TEST_F(AddShardTest, AddExistingShardStandalone) {
     // can't change the sharded cluster's notion of the shard from standalone to replica set just
     // by calling addShard.
     auto future3 = launchAsync([&] {
-        ON_BLOCK_EXIT([&] { Client::destroy(); });
-        Client::initThreadIfNotAlready();
+        ThreadClient tc(getGlobalServiceContext());
         ASSERT_EQUALS(ErrorCodes::IllegalOperation,
                       ShardingCatalogManager::get(operationContext())
                           ->addShard(operationContext(),
@@ -1184,8 +1167,7 @@ TEST_F(AddShardTest, AddExistingShardStandalone) {
 
     // Adding the same standalone host with the same options should succeed.
     auto future4 = launchAsync([&] {
-        ON_BLOCK_EXIT([&] { Client::destroy(); });
-        Client::initThreadIfNotAlready();
+        ThreadClient tc(getGlobalServiceContext());
         auto shardName = assertGet(ShardingCatalogManager::get(operationContext())
                                        ->addShard(operationContext(),
                                                   &existingShardName,
@@ -1201,8 +1183,7 @@ TEST_F(AddShardTest, AddExistingShardStandalone) {
     // Adding the same standalone host with the same options (without explicitly specifying the
     // shard name) should succeed.
     auto future5 = launchAsync([&] {
-        ON_BLOCK_EXIT([&] { Client::destroy(); });
-        Client::initThreadIfNotAlready();
+        ThreadClient tc(getGlobalServiceContext());
         auto shardName = assertGet(ShardingCatalogManager::get(operationContext())
                                        ->addShard(operationContext(),
                                                   nullptr,
@@ -1245,8 +1226,7 @@ TEST_F(AddShardTest, AddExistingShardReplicaSet) {
     // Adding the same connection string with a different shard name should fail.
     std::string differentName = "anotherShardName";
     auto future1 = launchAsync([&] {
-        ON_BLOCK_EXIT([&] { Client::destroy(); });
-        Client::initThreadIfNotAlready();
+        ThreadClient tc(getGlobalServiceContext());
         ASSERT_EQUALS(
             ErrorCodes::IllegalOperation,
             ShardingCatalogManager::get(operationContext())
@@ -1260,8 +1240,7 @@ TEST_F(AddShardTest, AddExistingShardReplicaSet) {
 
     // Adding the same connection string with a different maxSize should fail.
     auto future2 = launchAsync([&] {
-        ON_BLOCK_EXIT([&] { Client::destroy(); });
-        Client::initThreadIfNotAlready();
+        ThreadClient tc(getGlobalServiceContext());
         ASSERT_EQUALS(
             ErrorCodes::IllegalOperation,
             ShardingCatalogManager::get(operationContext())
@@ -1279,8 +1258,7 @@ TEST_F(AddShardTest, AddExistingShardReplicaSet) {
     // the sharded cluster's notion of the shard from replica set to standalone just by calling
     // addShard.
     auto future3 = launchAsync([&] {
-        ON_BLOCK_EXIT([&] { Client::destroy(); });
-        Client::initThreadIfNotAlready();
+        ThreadClient tc(getGlobalServiceContext());
         ASSERT_EQUALS(ErrorCodes::IllegalOperation,
                       ShardingCatalogManager::get(operationContext())
                           ->addShard(operationContext(),
@@ -1298,8 +1276,7 @@ TEST_F(AddShardTest, AddExistingShardReplicaSet) {
     // change the replica set name the sharded cluster knows for it just by calling addShard again.
     std::string differentSetName = "differentSet";
     auto future4 = launchAsync([&] {
-        ON_BLOCK_EXIT([&] { Client::destroy(); });
-        Client::initThreadIfNotAlready();
+        ThreadClient tc(getGlobalServiceContext());
         ASSERT_EQUALS(ErrorCodes::IllegalOperation,
                       ShardingCatalogManager::get(operationContext())
                           ->addShard(operationContext(),
@@ -1315,8 +1292,7 @@ TEST_F(AddShardTest, AddExistingShardReplicaSet) {
 
     // Adding the same host with the same options should succeed.
     auto future5 = launchAsync([&] {
-        ON_BLOCK_EXIT([&] { Client::destroy(); });
-        Client::initThreadIfNotAlready();
+        ThreadClient tc(getGlobalServiceContext());
         auto shardName = assertGet(ShardingCatalogManager::get(operationContext())
                                        ->addShard(operationContext(),
                                                   &existingShardName,
@@ -1329,8 +1305,7 @@ TEST_F(AddShardTest, AddExistingShardReplicaSet) {
     // Adding the same host with the same options (without explicitly specifying the shard name)
     // should succeed.
     auto future6 = launchAsync([&] {
-        ON_BLOCK_EXIT([&] { Client::destroy(); });
-        Client::initThreadIfNotAlready();
+        ThreadClient tc(getGlobalServiceContext());
         auto shardName = assertGet(
             ShardingCatalogManager::get(operationContext())
                 ->addShard(operationContext(), nullptr, connString, existingShard.getMaxSizeMB()));
@@ -1354,8 +1329,7 @@ TEST_F(AddShardTest, AddExistingShardReplicaSet) {
         targeterFactory()->addTargeterToReturn(otherHostConnString, std::move(otherHostTargeter));
     }
     auto future7 = launchAsync([&] {
-        ON_BLOCK_EXIT([&] { Client::destroy(); });
-        Client::initThreadIfNotAlready();
+        ThreadClient tc(getGlobalServiceContext());
         auto shardName = assertGet(ShardingCatalogManager::get(operationContext())
                                        ->addShard(operationContext(),
                                                   nullptr,
diff --git a/src/mongo/db/s/config/sharding_catalog_manager_create_collection_test.cpp b/src/mongo/db/s/config/sharding_catalog_manager_create_collection_test.cpp
index 43d378f2a3a..79f1d38c7c0 100644
--- a/src/mongo/db/s/config/sharding_catalog_manager_create_collection_test.cpp
+++ b/src/mongo/db/s/config/sharding_catalog_manager_create_collection_test.cpp
@@ -167,9 +167,7 @@ TEST_F(CreateCollectionTest, BaseCase) {
     requestOptions.cappedSize = 256;
 
     auto future = launchAsync([this, &testNS, &requestOptions] {
-        ON_BLOCK_EXIT([&] { Client::destroy(); });
-
-        Client::initThreadIfNotAlready("BaseCaseTest");
+        ThreadClient tc("BaseCaseTest", getGlobalServiceContext());
         auto opCtx = cc().makeOperationContext();
         ShardingCatalogManager::get(opCtx.get())
             ->createCollection(opCtx.get(), testNS, requestOptions);
diff --git a/src/mongo/db/s/config/sharding_catalog_manager_create_database_test.cpp b/src/mongo/db/s/config/sharding_catalog_manager_create_database_test.cpp
index 159fc584373..c2db2628ce5 100644
--- a/src/mongo/db/s/config/sharding_catalog_manager_create_database_test.cpp
+++ b/src/mongo/db/s/config/sharding_catalog_manager_create_database_test.cpp
@@ -100,8 +100,7 @@ TEST_F(CreateDatabaseTest, createDatabaseSuccess) {
     // Now actually start the createDatabase work.
 
     auto future = launchAsync([this, dbname] {
-        ON_BLOCK_EXIT([&] { Client::destroy(); });
-        Client::initThreadIfNotAlready("Test");
+        ThreadClient tc("Test", getGlobalServiceContext());
         auto opCtx = cc().makeOperationContext();
         ShardingCatalogManager::get(opCtx.get())->createDatabase(opCtx.get(), dbname);
     });
diff --git a/src/mongo/db/s/config/sharding_catalog_manager_drop_coll_test.cpp b/src/mongo/db/s/config/sharding_catalog_manager_drop_coll_test.cpp
index 699b83c44e3..ffc56af57cb 100644
--- a/src/mongo/db/s/config/sharding_catalog_manager_drop_coll_test.cpp
+++ b/src/mongo/db/s/config/sharding_catalog_manager_drop_coll_test.cpp
@@ -165,8 +165,7 @@ public:
     }
 
     Status doDrop() {
-        ON_BLOCK_EXIT([&] { Client::destroy(); });
-        Client::initThreadIfNotAlready("Test");
+        ThreadClient tc("Test", getGlobalServiceContext());
         auto opCtx = cc().makeOperationContext();
         return ShardingCatalogManager::get(opCtx.get())->dropCollection(opCtx.get(), dropNS());
     }
diff --git a/src/mongo/db/s/config/sharding_catalog_manager_enable_sharding_test.cpp b/src/mongo/db/s/config/sharding_catalog_manager_enable_sharding_test.cpp
index 83ed91c88cc..1ab2be440f7 100644
--- a/src/mongo/db/s/config/sharding_catalog_manager_enable_sharding_test.cpp
+++ b/src/mongo/db/s/config/sharding_catalog_manager_enable_sharding_test.cpp
@@ -79,8 +79,7 @@ TEST_F(EnableShardingTest, noDBExists) {
     shardTargeter->setFindHostReturnValue(HostAndPort("shard0:12"));
 
     auto future = launchAsync([&] {
-        ON_BLOCK_EXIT([&] { Client::destroy(); });
-        Client::initThreadIfNotAlready("Test");
+        ThreadClient tc("Test", getGlobalServiceContext());
         auto opCtx = cc().makeOperationContext();
         ShardingCatalogManager::get(opCtx.get())->enableSharding(opCtx.get(), "db1");
     });
diff --git a/src/mongo/db/s/config/sharding_catalog_manager_shard_collection_test.cpp b/src/mongo/db/s/config/sharding_catalog_manager_shard_collection_test.cpp
index 62b24c06268..f286d42e89b 100644
--- a/src/mongo/db/s/config/sharding_catalog_manager_shard_collection_test.cpp
+++ b/src/mongo/db/s/config/sharding_catalog_manager_shard_collection_test.cpp
@@ -172,8 +172,7 @@ TEST_F(ShardCollectionTest, noInitialChunksOrData) {
 
     // Now start actually sharding the collection.
     auto future = launchAsync([&] {
-        ON_BLOCK_EXIT([&] { Client::destroy(); });
-        Client::initThreadIfNotAlready("Test");
+        ThreadClient tc("Test", getGlobalServiceContext());
         auto opCtx = cc().makeOperationContext();
         ShardingCatalogManager::get(operationContext())
             ->shardCollection(opCtx.get(),
@@ -295,8 +294,7 @@ TEST_F(ShardCollectionTest, withInitialChunks) {
         // TODO: can we mock the ShardRegistry to return these?
         set<ShardId> shards{shard0.getName(), shard1.getName(), shard2.getName()};
 
-        ON_BLOCK_EXIT([&] { Client::destroy(); });
-        Client::initThreadIfNotAlready("Test");
+        ThreadClient tc("Test", getGlobalServiceContext());
         auto opCtx = cc().makeOperationContext();
         ShardingCatalogManager::get(operationContext())
             ->shardCollection(opCtx.get(),
@@ -391,8 +389,7 @@ TEST_F(ShardCollectionTest, withInitialData) {
 
     // Now start actually sharding the collection.
     auto future = launchAsync([&] {
-        ON_BLOCK_EXIT([&] { Client::destroy(); });
-        Client::initThreadIfNotAlready("Test");
+        ThreadClient tc("Test", getGlobalServiceContext());
         auto opCtx = cc().makeOperationContext();
         ShardingCatalogManager::get(operationContext())
             ->shardCollection(opCtx.get(),
diff --git a/src/mongo/db/s/implicit_create_collection_test.cpp b/src/mongo/db/s/implicit_create_collection_test.cpp
index 0c1a08e7b72..fa9d140ed6b 100644
--- a/src/mongo/db/s/implicit_create_collection_test.cpp
+++ b/src/mongo/db/s/implicit_create_collection_test.cpp
@@ -70,8 +70,7 @@ public:
 TEST_F(ImplicitCreateTest, NormalCreate) {
     const NamespaceString kNs("test.user");
     auto future = launchAsync([this, &kNs] {
-        ON_BLOCK_EXIT([&] { Client::destroy(); });
-        Client::initThreadIfNotAlready("Test");
+        ThreadClient tc("Test", getGlobalServiceContext());
         auto opCtx = cc().makeOperationContext();
         ASSERT_OK(onCannotImplicitlyCreateCollection(opCtx.get(), kNs));
     });
@@ -84,8 +83,7 @@ TEST_F(ImplicitCreateTest, NormalCreate) {
 TEST_F(ImplicitCreateTest, CanCallOnCannotImplicitAgainAfterError) {
     const NamespaceString kNs("test.user");
     auto future = launchAsync([this, &kNs] {
-        ON_BLOCK_EXIT([&] { Client::destroy(); });
-        Client::initThreadIfNotAlready("Test");
+        ThreadClient tc("Test", getGlobalServiceContext());
         auto opCtx = cc().makeOperationContext();
         auto status = onCannotImplicitlyCreateCollection(opCtx.get(), kNs);
         ASSERT_EQ(ErrorCodes::FailPointEnabled, status);
@@ -100,8 +98,7 @@ TEST_F(ImplicitCreateTest, CanCallOnCannotImplicitAgainAfterError) {
     // Retry, but this time config server will return success
 
     future = launchAsync([this, &kNs] {
-        ON_BLOCK_EXIT([&] { Client::destroy(); });
-        Client::initThreadIfNotAlready("Test");
+        ThreadClient tc("Test", getGlobalServiceContext());
         auto opCtx = cc().makeOperationContext();
         ASSERT_OK(onCannotImplicitlyCreateCollection(opCtx.get(), kNs));
     });
@@ -114,8 +111,7 @@ TEST_F(ImplicitCreateTest, CanCallOnCannotImplicitAgainAfterError) {
 TEST_F(ImplicitCreateTest, ShouldNotCallConfigCreateIfCollectionExists) {
     const NamespaceString kNs("test.user");
     auto future = launchAsync([this, &kNs] {
-        ON_BLOCK_EXIT([&] { Client::destroy(); });
-        Client::initThreadIfNotAlready("Test");
+        ThreadClient tc("Test", getGlobalServiceContext());
         auto opCtx = cc().makeOperationContext();
         auto status = onCannotImplicitlyCreateCollection(opCtx.get(), kNs);
         ASSERT_EQ(ErrorCodes::FailPointEnabled, status);
@@ -135,8 +131,7 @@ TEST_F(ImplicitCreateTest, ShouldNotCallConfigCreateIfCollectionExists) {
     // Retry, but this time config server will return success
 
     future = launchAsync([this, &kNs] {
-        ON_BLOCK_EXIT([&] { Client::destroy(); });
-        Client::initThreadIfNotAlready("Test");
+        ThreadClient tc("Test", getGlobalServiceContext());
         auto opCtx = cc().makeOperationContext();
         ASSERT_OK(onCannotImplicitlyCreateCollection(opCtx.get(), kNs));
     });
diff --git a/src/mongo/db/service_context_test_fixture.cpp b/src/mongo/db/service_context_test_fixture.cpp
index 46d92935bb8..e79c8ab7ea3 100644
--- a/src/mongo/db/service_context_test_fixture.cpp
+++ b/src/mongo/db/service_context_test_fixture.cpp
@@ -55,13 +55,7 @@ ServiceContext* ScopedGlobalServiceContextForTest::getServiceContext() {
     return getGlobalServiceContext();
 }
 
-ServiceContextTest::ServiceContextTest() {
-    Client::initThread(getThreadName());
-}
-
-ServiceContextTest::~ServiceContextTest() {
-    Client::destroy();
-}
+ServiceContextTest::ServiceContextTest() : _threadClient(getGlobalServiceContext()) {}
 
 Client* ServiceContextTest::getClient() {
     return Client::getCurrent();
diff --git a/src/mongo/db/service_context_test_fixture.h b/src/mongo/db/service_context_test_fixture.h
index 404a6ba316c..a81962478fd 100644
--- a/src/mongo/db/service_context_test_fixture.h
+++ b/src/mongo/db/service_context_test_fixture.h
@@ -66,7 +66,8 @@ public:
 
 protected:
     ServiceContextTest();
-    virtual ~ServiceContextTest();
+    virtual ~ServiceContextTest() = default;
+    ThreadClient _threadClient;
 };
 
 }  // namespace mongo
diff --git a/src/mongo/db/session_catalog_test.cpp b/src/mongo/db/session_catalog_test.cpp
index c5e4a52b7c6..1f8312b6e69 100644
--- a/src/mongo/db/session_catalog_test.cpp
+++ b/src/mongo/db/session_catalog_test.cpp
@@ -123,8 +123,7 @@ TEST_F(SessionCatalogTestWithDefaultOpCtx, GetOrCreateSessionAfterCheckOutSessio
     ocs.emplace(_opCtx, true);
 
     stdx::async(stdx::launch::async, [&] {
-        ON_BLOCK_EXIT([&] { Client::destroy(); });
-        Client::initThreadIfNotAlready();
+        ThreadClient tc(getGlobalServiceContext());
         auto sideOpCtx = Client::getCurrent()->makeOperationContext();
         auto scopedSession =
             SessionCatalog::get(sideOpCtx.get())->getOrCreateSession(sideOpCtx.get(), lsid);
@@ -136,8 +135,7 @@ TEST_F(SessionCatalogTestWithDefaultOpCtx, GetOrCreateSessionAfterCheckOutSessio
     ocs.reset();
 
     stdx::async(stdx::launch::async, [&] {
-        ON_BLOCK_EXIT([&] { Client::destroy(); });
-        Client::initThreadIfNotAlready();
+        ThreadClient tc(getGlobalServiceContext());
         auto sideOpCtx = Client::getCurrent()->makeOperationContext();
         auto scopedSession =
             SessionCatalog::get(sideOpCtx.get())->getOrCreateSession(sideOpCtx.get(), lsid);
@@ -234,8 +232,7 @@ TEST_F(SessionCatalogTest, KillSessionWhenSessionIsNotCheckedOut) {
     // Schedule a separate "regular operation" thread, which will block on checking-out the session,
     // which we will use to confirm that session kill completion actually unblocks check-out
     auto future = stdx::async(stdx::launch::async, [lsid] {
-        ON_BLOCK_EXIT([&] { Client::destroy(); });
-        Client::initThreadIfNotAlready();
+        ThreadClient tc(getGlobalServiceContext());
         auto sideOpCtx = Client::getCurrent()->makeOperationContext();
         sideOpCtx->setLogicalSessionId(lsid);
 
@@ -279,8 +276,7 @@ TEST_F(SessionCatalogTest, KillSessionWhenSessionIsCheckedOut) {
         // Make sure that the checkOutForKill call will wait for the owning operation context to
         // check the session back in
         auto future = stdx::async(stdx::launch::async, [lsid] {
-            ON_BLOCK_EXIT([&] { Client::destroy(); });
-            Client::initThreadIfNotAlready();
+            ThreadClient tc(getGlobalServiceContext());
             auto sideOpCtx = Client::getCurrent()->makeOperationContext();
             sideOpCtx->setLogicalSessionId(lsid);
             sideOpCtx->setDeadlineAfterNowBy(Milliseconds(10), ErrorCodes::MaxTimeMSExpired);
@@ -306,8 +302,7 @@ TEST_F(SessionCatalogTest, KillSessionWhenSessionIsCheckedOut) {
     // Schedule a separate "regular operation" thread, which will block on checking-out the session,
     // which we will use to confirm that session kill completion actually unblocks check-out
     auto future = stdx::async(stdx::launch::async, [lsid] {
-        ON_BLOCK_EXIT([&] { Client::destroy(); });
-        Client::initThreadIfNotAlready();
+        ThreadClient tc(getGlobalServiceContext());
         auto sideOpCtx = Client::getCurrent()->makeOperationContext();
         sideOpCtx->setLogicalSessionId(lsid);
 
@@ -387,8 +382,7 @@ TEST_F(SessionCatalogTestWithDefaultOpCtx, KillSessionsThroughScanSessions) {
     for (const auto& lsid : lsids) {
         futures.emplace_back(
             stdx::async(stdx::launch::async, [lsid, &firstUseOfTheSessionReachedBarrier] {
-                ON_BLOCK_EXIT([&] { Client::destroy(); });
-                Client::initThreadIfNotAlready();
+                ThreadClient tc(getGlobalServiceContext());
 
                 {
                     auto sideOpCtx = Client::getCurrent()->makeOperationContext();
diff --git a/src/mongo/db/storage/SConscript b/src/mongo/db/storage/SConscript
index 170e7082139..ad1295dfb0a 100644
--- a/src/mongo/db/storage/SConscript
+++ b/src/mongo/db/storage/SConscript
@@ -116,8 +116,8 @@ env.Library(
     LIBDEPS=[
         '$BUILD_DIR/mongo/db/storage/storage_options',
         '$BUILD_DIR/mongo/db/service_context',
+        '$BUILD_DIR/mongo/db/service_context_test_fixture',
     ],
-
 )
 
 env.Library(
diff --git a/src/mongo/db/storage/kv/kv_engine_timestamps_test.cpp b/src/mongo/db/storage/kv/kv_engine_timestamps_test.cpp
index fb935460769..9cf5bec545f 100644
--- a/src/mongo/db/storage/kv/kv_engine_timestamps_test.cpp
+++ b/src/mongo/db/storage/kv/kv_engine_timestamps_test.cpp
@@ -48,7 +48,7 @@
 namespace mongo {
 namespace {
 
-class SnapshotManagerTests : public ServiceContextTest {
+class SnapshotManagerTests : public unittest::Test, public ScopedGlobalServiceContextForTest {
 public:
     /**
      * Usable as an OperationContext* but owns both the Client and the OperationContext.
diff --git a/src/mongo/db/storage/test_harness_helper.cpp b/src/mongo/db/storage/test_harness_helper.cpp
index aabdfdd7315..2f06d66f359 100644
--- a/src/mongo/db/storage/test_harness_helper.cpp
+++ b/src/mongo/db/storage/test_harness_helper.cpp
@@ -40,16 +40,7 @@ namespace {
 stdx::function<std::unique_ptr<HarnessHelper>()> basicHarnessFactory;
 }  // namespace
 
-
-HarnessHelper::HarnessHelper() {
-    setGlobalServiceContext(ServiceContext::make());
-    Client::initThread(getThreadName());
-}
-
-HarnessHelper::~HarnessHelper() {
-    Client::destroy();
-    setGlobalServiceContext({});
-}
+HarnessHelper::HarnessHelper() : _threadClient(getGlobalServiceContext()) {}
 
 void registerHarnessHelperFactory(stdx::function<std::unique_ptr<HarnessHelper>()> factory) {
     basicHarnessFactory = std::move(factory);
diff --git a/src/mongo/db/storage/test_harness_helper.h b/src/mongo/db/storage/test_harness_helper.h
index c5c5216b4b6..fe0c2fa0a8f 100644
--- a/src/mongo/db/storage/test_harness_helper.h
+++ b/src/mongo/db/storage/test_harness_helper.h
@@ -38,6 +38,7 @@
 #include "mongo/db/operation_context_noop.h"
 #include "mongo/db/record_id.h"
 #include "mongo/db/service_context.h"
+#include "mongo/db/service_context_test_fixture.h"
 #include "mongo/db/storage/sorted_data_interface.h"
 #include "mongo/stdx/functional.h"
 #include "mongo/stdx/memory.h"
@@ -53,10 +54,9 @@ namespace mongo {
  * HarnessHelper implementation. The newRecoveryUnit() implementation dictates what RecoveryUnit
  * implementation the OperationContext has.
  */
-class HarnessHelper {
+class HarnessHelper : public ScopedGlobalServiceContextForTest {
 public:
-    virtual ~HarnessHelper();
-
+    virtual ~HarnessHelper() = default;
     explicit HarnessHelper();
 
     virtual ServiceContext::UniqueOperationContext newOperationContext(Client* const client) {
@@ -83,6 +83,9 @@ public:
     }
 
     virtual std::unique_ptr<RecoveryUnit> newRecoveryUnit() = 0;
+
+protected:
+    ThreadClient _threadClient;
 };
 
 namespace harness_helper_detail {
diff --git a/src/mongo/db/storage/wiredtiger/SConscript b/src/mongo/db/storage/wiredtiger/SConscript
index 5f66816a7f3..8d3d406d57d 100644
--- a/src/mongo/db/storage/wiredtiger/SConscript
+++ b/src/mongo/db/storage/wiredtiger/SConscript
@@ -255,6 +255,7 @@ if wiredtiger:
             LIBDEPS_PRIVATE=[
                 '$BUILD_DIR/mongo/db/repl/repl_coordinator_interface',
                 '$BUILD_DIR/mongo/db/repl/replmocks',
+                '$BUILD_DIR/mongo/db/service_context_test_fixture',
             ],
         )
 
diff --git a/src/mongo/db/storage/wiredtiger/wiredtiger_kv_engine.cpp b/src/mongo/db/storage/wiredtiger/wiredtiger_kv_engine.cpp
index cb390080cf2..a8187e89699 100644
--- a/src/mongo/db/storage/wiredtiger/wiredtiger_kv_engine.cpp
+++ b/src/mongo/db/storage/wiredtiger/wiredtiger_kv_engine.cpp
@@ -179,9 +179,7 @@ public:
     }
 
     virtual void run() {
-        Client::initThread(name().c_str());
-        ON_BLOCK_EXIT([] { Client::destroy(); });
-
+        ThreadClient tc(name(), getGlobalServiceContext());
         LOG(1) << "starting " << name() << " thread";
 
         while (!_shuttingDown.load()) {
@@ -227,9 +225,7 @@ public:
     }
 
     virtual void run() {
-        Client::initThread(name().c_str());
-        ON_BLOCK_EXIT([] { Client::destroy(); });
-
+        ThreadClient tc(name(), getGlobalServiceContext());
         LOG(1) << "starting " << name() << " thread";
 
         while (!_shuttingDown.load()) {
diff --git a/src/mongo/db/storage/wiredtiger/wiredtiger_kv_engine_test.cpp b/src/mongo/db/storage/wiredtiger/wiredtiger_kv_engine_test.cpp
index b8664e9725b..61942d6a0f5 100644
--- a/src/mongo/db/storage/wiredtiger/wiredtiger_kv_engine_test.cpp
+++ b/src/mongo/db/storage/wiredtiger/wiredtiger_kv_engine_test.cpp
@@ -40,6 +40,7 @@
 #include "mongo/db/repl/repl_settings.h"
 #include "mongo/db/repl/replication_coordinator_mock.h"
 #include "mongo/db/service_context.h"
+#include "mongo/db/service_context_test_fixture.h"
 #include "mongo/db/storage/wiredtiger/wiredtiger_global_options.h"
 #include "mongo/db/storage/wiredtiger/wiredtiger_kv_engine.h"
 #include "mongo/db/storage/wiredtiger/wiredtiger_record_store.h"
@@ -51,12 +52,11 @@
 namespace mongo {
 namespace {
 
-class WiredTigerKVHarnessHelper : public KVHarnessHelper {
+class WiredTigerKVHarnessHelper : public KVHarnessHelper, public ScopedGlobalServiceContextForTest {
 public:
     WiredTigerKVHarnessHelper(bool forRepair = false)
         : _dbpath("wt-kv-harness"), _forRepair(forRepair) {
-        if (!hasGlobalServiceContext())
-            setGlobalServiceContext(ServiceContext::make());
+        invariant(hasGlobalServiceContext());
         _engine.reset(makeEngine());
         repl::ReplicationCoordinator::set(
             getGlobalServiceContext(),
@@ -64,11 +64,6 @@ public:
                 getGlobalServiceContext(), repl::ReplSettings())));
     }
 
-    virtual ~WiredTigerKVHarnessHelper() {
-        _engine.reset(nullptr);
-        // Cannot cleanup the global service context here, the test still have clients remaining.
-    }
-
     virtual KVEngine* restartEngine() override {
         _engine.reset(nullptr);
         _engine.reset(makeEngine());
@@ -102,39 +97,23 @@ private:
     bool _forRepair;
 };
 
-class WiredTigerKVEngineTest : public unittest::Test {
+class WiredTigerKVEngineTest : public unittest::Test, public ScopedGlobalServiceContextForTest {
 public:
-    void setUp() override {
-        setGlobalServiceContext(ServiceContext::make());
-        Client::initThread(getThreadName());
-
-        _helper = makeHelper();
-        _engine = _helper->getWiredTigerKVEngine();
-    }
-
-    void tearDown() override {
-        _helper.reset(nullptr);
-        Client::destroy();
-        setGlobalServiceContext({});
-    }
+    WiredTigerKVEngineTest(bool repair = false)
+        : _helper(repair), _engine(_helper.getWiredTigerKVEngine()) {}
 
     std::unique_ptr<OperationContext> makeOperationContext() {
         return std::make_unique<OperationContextNoop>(_engine->newRecoveryUnit());
     }
 
 protected:
-    virtual std::unique_ptr<WiredTigerKVHarnessHelper> makeHelper() {
-        return std::make_unique<WiredTigerKVHarnessHelper>();
-    }
-
-    std::unique_ptr<WiredTigerKVHarnessHelper> _helper;
+    WiredTigerKVHarnessHelper _helper;
     WiredTigerKVEngine* _engine;
 };
 
 class WiredTigerKVEngineRepairTest : public WiredTigerKVEngineTest {
-    virtual std::unique_ptr<WiredTigerKVHarnessHelper> makeHelper() override {
-        return std::make_unique<WiredTigerKVHarnessHelper>(true /* repair */);
-    }
+public:
+    WiredTigerKVEngineRepairTest() : WiredTigerKVEngineTest(true /* repair */) {}
 };
 
 TEST_F(WiredTigerKVEngineRepairTest, OrphanedDataFilesCanBeRecovered) {
diff --git a/src/mongo/db/storage/wiredtiger/wiredtiger_record_store_mongod.cpp b/src/mongo/db/storage/wiredtiger/wiredtiger_record_store_mongod.cpp
index fdc45e0c54f..375417f2e40 100644
--- a/src/mongo/db/storage/wiredtiger/wiredtiger_record_store_mongod.cpp
+++ b/src/mongo/db/storage/wiredtiger/wiredtiger_record_store_mongod.cpp
@@ -128,8 +128,7 @@ public:
     }
 
     virtual void run() {
-        Client::initThread(_name.c_str());
-        ON_BLOCK_EXIT([] { Client::destroy(); });
+        ThreadClient tc(_name, getGlobalServiceContext());
 
         while (!globalInShutdownDeprecated()) {
             if (!_deleteExcessDocuments()) {
diff --git a/src/mongo/db/thread_client_test.cpp b/src/mongo/db/thread_client_test.cpp
new file mode 100644
index 00000000000..e32e94d49d6
--- /dev/null
+++ b/src/mongo/db/thread_client_test.cpp
@@ -0,0 +1,92 @@
+
+/**
+ *    Copyright (C) 2018-present MongoDB, Inc.
+ *
+ *    This program is free software: you can redistribute it and/or modify
+ *    it under the terms of the Server Side Public License, version 1,
+ *    as published by MongoDB, Inc.
+ *
+ *    This program is distributed in the hope that it will be useful,
+ *    but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *    Server Side Public License for more details.
+ *
+ *    You should have received a copy of the Server Side Public License
+ *    along with this program. If not, see
+ *    <http://www.mongodb.com/licensing/server-side-public-license>.
+ *
+ *    As a special exception, the copyright holders give permission to link the
+ *    code of portions of this program with the OpenSSL library under certain
+ *    conditions as described in each individual source file and distribute
+ *    linked combinations including the program with the OpenSSL library. You
+ *    must comply with the Server Side Public License in all respects for
+ *    all of the code used other than as permitted herein. If you modify file(s)
+ *    with this exception, you may extend this exception to your version of the
+ *    file(s), but you are not obligated to do so. If you do not wish to do so,
+ *    delete this exception statement from your version. If you delete this
+ *    exception statement from all source files in the program, then also delete
+ *    it in the license file.
+ */
+
+#include "mongo/platform/basic.h"
+
+#include "mongo/db/client.h"
+#include "mongo/db/service_context_test_fixture.h"
+#include "mongo/transport/transport_layer_mock.h"
+#include "mongo/unittest/unittest.h"
+#include "mongo/util/assert_util.h"
+
+namespace mongo {
+namespace {
+
+class ThreadClientTest : public unittest::Test, public ScopedGlobalServiceContextForTest {};
+
+TEST_F(ThreadClientTest, TestNoAssignment) {
+    ASSERT_FALSE(haveClient());
+    { ThreadClient tc(getThreadName(), getGlobalServiceContext()); }
+    ASSERT_FALSE(haveClient());
+}
+
+TEST_F(ThreadClientTest, TestAssignment) {
+    ASSERT_FALSE(haveClient());
+    ThreadClient threadClient(getThreadName(), getGlobalServiceContext());
+    ASSERT_TRUE(haveClient());
+}
+
+TEST_F(ThreadClientTest, TestDifferentArgs) {
+    {
+        ASSERT_FALSE(haveClient());
+        ThreadClient tc(getGlobalServiceContext());
+        ASSERT_TRUE(haveClient());
+    }
+    {
+        ASSERT_FALSE(haveClient());
+        ThreadClient tc("Test", getGlobalServiceContext());
+        ASSERT_TRUE(haveClient());
+    }
+    {
+        ASSERT_FALSE(haveClient());
+        transport::TransportLayerMock mock;
+        transport::SessionHandle handle = mock.createSession();
+        ThreadClient tc(getThreadName(), getGlobalServiceContext(), handle);
+        ASSERT_TRUE(haveClient());
+    }
+    {
+        ASSERT_FALSE(haveClient());
+        ServiceContext sc;
+        ThreadClient tc("Test", &sc, nullptr);
+        ASSERT_TRUE(haveClient());
+    }
+}
+
+TEST_F(ThreadClientTest, TestAlternativeClientRegion) {
+    ASSERT_FALSE(haveClient());
+    ThreadClient threadClient(getThreadName(), getGlobalServiceContext());
+
+    ServiceContext::UniqueClient swapClient = getGlobalServiceContext()->makeClient("swapClient");
+    { AlternativeClientRegion altRegion(swapClient); }
+
+    ASSERT_TRUE(haveClient());
+}
+}  // namespace
+}  // namespace mongo
diff --git a/src/mongo/db/ttl.cpp b/src/mongo/db/ttl.cpp
index 8ade3873fb1..99a1ef15a9c 100644
--- a/src/mongo/db/ttl.cpp
+++ b/src/mongo/db/ttl.cpp
@@ -91,8 +91,7 @@ public:
     static std::string secondsExpireField;
 
     virtual void run() {
-        Client::initThread(name().c_str());
-        ON_BLOCK_EXIT([] { Client::destroy(); });
+        ThreadClient tc(name(), getGlobalServiceContext());
         AuthorizationSession::get(cc())->grantInternalAuthorization();
 
         while (!globalInShutdownDeprecated()) {
diff --git a/src/mongo/embedded/embedded.cpp b/src/mongo/embedded/embedded.cpp
index 7589bb22a44..5c54a5609a3 100644
--- a/src/mongo/embedded/embedded.cpp
+++ b/src/mongo/embedded/embedded.cpp
@@ -139,41 +139,37 @@ using std::endl;
 
 void shutdown(ServiceContext* srvContext) {
 
-    Client::initThreadIfNotAlready();
-    auto const client = Client::getCurrent();
-    auto const serviceContext = client->getServiceContext();
-    invariant(srvContext == serviceContext);
-
-    serviceContext->setKillAllOperations();
-
-    // We should always be able to acquire the global lock at shutdown.
-    // Close all open databases, shutdown storage engine and run all deinitializers.
-    auto shutdownOpCtx = serviceContext->makeOperationContext(client);
     {
-        UninterruptibleLockGuard noInterrupt(shutdownOpCtx->lockState());
-        Lock::GlobalLock lk(shutdownOpCtx.get(), MODE_X);
-        DatabaseHolder::getDatabaseHolder().closeAll(shutdownOpCtx.get(), "shutdown");
+        ThreadClient tc(srvContext);
+        auto const client = Client::getCurrent();
+        auto const serviceContext = client->getServiceContext();
 
-        LogicalSessionCache::set(serviceContext, nullptr);
+        serviceContext->setKillAllOperations();
 
-        // Shut down the background periodic task runner
-        if (auto runner = serviceContext->getPeriodicRunner()) {
-            runner->shutdown();
-        }
+        // We should always be able to acquire the global lock at shutdown.
+        // Close all open databases, shutdown storage engine and run all deinitializers.
+        auto shutdownOpCtx = serviceContext->makeOperationContext(client);
+        {
+            UninterruptibleLockGuard noInterrupt(shutdownOpCtx->lockState());
+            Lock::GlobalLock lk(shutdownOpCtx.get(), MODE_X);
+            DatabaseHolder::getDatabaseHolder().closeAll(shutdownOpCtx.get(), "shutdown");
 
-        // Global storage engine may not be started in all cases before we exit
-        if (serviceContext->getStorageEngine()) {
-            shutdownGlobalStorageEngineCleanly(serviceContext);
-        }
+            LogicalSessionCache::set(serviceContext, nullptr);
 
-        Status status = mongo::runGlobalDeinitializers();
-        uassertStatusOKWithContext(status, "Global deinitilization failed");
-    }
-    shutdownOpCtx.reset();
+            // Shut down the background periodic task runner
+            if (auto runner = serviceContext->getPeriodicRunner()) {
+                runner->shutdown();
+            }
 
-    if (Client::getCurrent())
-        Client::destroy();
+            // Global storage engine may not be started in all cases before we exit
+            if (serviceContext->getStorageEngine()) {
+                shutdownGlobalStorageEngineCleanly(serviceContext);
+            }
 
+            Status status = mongo::runGlobalDeinitializers();
+            uassertStatusOKWithContext(status, "Global deinitilization failed");
+        }
+    }
     setGlobalServiceContext(nullptr);
 
     log(LogComponent::kControl) << "now exiting";
diff --git a/src/mongo/s/catalog/dist_lock_catalog_impl_test.cpp b/src/mongo/s/catalog/dist_lock_catalog_impl_test.cpp
index e0c9db25298..f09b53fa36a 100644
--- a/src/mongo/s/catalog/dist_lock_catalog_impl_test.cpp
+++ b/src/mongo/s/catalog/dist_lock_catalog_impl_test.cpp
@@ -92,8 +92,7 @@ protected:
     auto launchOnSeparateThread(std::function<void(OperationContext*)> func) {
         auto const serviceContext = getServiceContext();
         return launchAsync([serviceContext, func] {
-            ON_BLOCK_EXIT([&] { Client::destroy(); });
-            Client::initThreadIfNotAlready("Test");
+            ThreadClient tc("Test", getGlobalServiceContext());
             auto opCtx = Client::getCurrent()->makeOperationContext();
             func(opCtx.get());
         });
diff --git a/src/mongo/s/query/cluster_cursor_cleanup_job.cpp b/src/mongo/s/query/cluster_cursor_cleanup_job.cpp
index ec5f65796b2..c1a76fe98ab 100644
--- a/src/mongo/s/query/cluster_cursor_cleanup_job.cpp
+++ b/src/mongo/s/query/cluster_cursor_cleanup_job.cpp
@@ -50,8 +50,7 @@ std::string ClusterCursorCleanupJob::name() const {
 }
 
 void ClusterCursorCleanupJob::run() {
-    Client::initThread(name().c_str());
-    ON_BLOCK_EXIT([] { Client::destroy(); });
+    ThreadClient tc(name(), getGlobalServiceContext());
 
     auto* const client = Client::getCurrent();
     auto* const manager = Grid::get(client->getServiceContext())->getCursorManager();