SERVER-39860 Separate reporting of RSTL and PBWM locks metrics in serverStatus and currentOp

8 files changed, 128 insertions, 144 deletions

diff --git a/src/mongo/db/concurrency/d_concurrency.cpp b/src/mongo/db/concurrency/d_concurrency.cpp
index c23e3937c2e..37c841594b0 100644
--- a/src/mongo/db/concurrency/d_concurrency.cpp
+++ b/src/mongo/db/concurrency/d_concurrency.cpp
@@ -215,8 +215,7 @@ void Lock::GlobalLock::waitForLockUntil(Date_t deadline) {
             throw;
     }
 
-    const ResourceId globalResId(RESOURCE_GLOBAL, ResourceId::SINGLETON_GLOBAL);
-    auto lockMode = _opCtx->lockState()->getLockMode(globalResId);
+    auto lockMode = _opCtx->lockState()->getLockMode(resourceIdGlobal);
     _opCtx->lockState()->setGlobalLockTakenInMode(lockMode);
 }
 
diff --git a/src/mongo/db/concurrency/d_concurrency_test.cpp b/src/mongo/db/concurrency/d_concurrency_test.cpp
index 3d400a9bceb..ddf60cc23a1 100644
--- a/src/mongo/db/concurrency/d_concurrency_test.cpp
+++ b/src/mongo/db/concurrency/d_concurrency_test.cpp
@@ -288,19 +288,17 @@ TEST_F(DConcurrencyTestFixture,
     opCtx->swapLockState(stdx::make_unique<LockerImpl>());
     auto lockState = opCtx->lockState();
 
-    const ResourceId globalId(RESOURCE_GLOBAL, ResourceId::SINGLETON_GLOBAL);
-
     auto globalWrite = stdx::make_unique<Lock::GlobalWrite>(opCtx.get());
     ASSERT(lockState->isW());
-    ASSERT(MODE_X == lockState->getLockMode(globalId))
-        << "unexpected global lock mode " << modeName(lockState->getLockMode(globalId));
+    ASSERT(MODE_X == lockState->getLockMode(resourceIdGlobal))
+        << "unexpected global lock mode " << modeName(lockState->getLockMode(resourceIdGlobal));
     ASSERT_EQ(lockState->getLockMode(resourceIdReplicationStateTransitionLock), MODE_IX);
 
     {
         Lock::DBLock dbWrite(opCtx.get(), "db", MODE_IX);
         ASSERT(lockState->isW());
-        ASSERT(MODE_X == lockState->getLockMode(globalId))
-            << "unexpected global lock mode " << modeName(lockState->getLockMode(globalId));
+        ASSERT(MODE_X == lockState->getLockMode(resourceIdGlobal))
+            << "unexpected global lock mode " << modeName(lockState->getLockMode(resourceIdGlobal));
 
         // If we destroy the GlobalWrite out of order relative to the DBLock, we will leave the
         // global lock resource locked in MODE_X. We have to explicitly downgrade this resource to
@@ -310,19 +308,19 @@ TEST_F(DConcurrencyTestFixture,
         ASSERT(lockState->isW());
         ASSERT_EQ(lockState->getLockMode(resourceIdReplicationStateTransitionLock), MODE_IX);
 
-        lockState->downgrade(globalId, MODE_IX);
+        lockState->downgrade(resourceIdGlobal, MODE_IX);
         ASSERT_FALSE(lockState->isW());
         ASSERT(lockState->isWriteLocked());
-        ASSERT(MODE_IX == lockState->getLockMode(globalId))
-            << "unexpected global lock mode " << modeName(lockState->getLockMode(globalId));
+        ASSERT(MODE_IX == lockState->getLockMode(resourceIdGlobal))
+            << "unexpected global lock mode " << modeName(lockState->getLockMode(resourceIdGlobal));
         ASSERT_EQ(lockState->getLockMode(resourceIdReplicationStateTransitionLock), MODE_IX);
     }
 
 
     ASSERT_FALSE(lockState->isW());
     ASSERT_FALSE(lockState->isWriteLocked());
-    ASSERT(MODE_NONE == lockState->getLockMode(globalId))
-        << "unexpected global lock mode " << modeName(lockState->getLockMode(globalId));
+    ASSERT(MODE_NONE == lockState->getLockMode(resourceIdGlobal))
+        << "unexpected global lock mode " << modeName(lockState->getLockMode(resourceIdGlobal));
     ASSERT_EQ(lockState->getLockMode(resourceIdReplicationStateTransitionLock), MODE_NONE);
 }
 
@@ -332,28 +330,26 @@ TEST_F(DConcurrencyTestFixture,
     opCtx->swapLockState(stdx::make_unique<LockerImpl>());
     auto lockState = opCtx->lockState();
 
-    const ResourceId globalId(RESOURCE_GLOBAL, ResourceId::SINGLETON_GLOBAL);
-
     auto globalWrite = stdx::make_unique<Lock::GlobalWrite>(opCtx.get());
     ASSERT(lockState->isW());
-    ASSERT(MODE_X == lockState->getLockMode(globalId))
-        << "unexpected global lock mode " << modeName(lockState->getLockMode(globalId));
+    ASSERT(MODE_X == lockState->getLockMode(resourceIdGlobal))
+        << "unexpected global lock mode " << modeName(lockState->getLockMode(resourceIdGlobal));
     ASSERT_EQ(lockState->getLockMode(resourceIdReplicationStateTransitionLock), MODE_IX);
 
     {
         Lock::DBLock dbWrite(opCtx.get(), "db", MODE_IX);
         ASSERT(lockState->isW());
-        ASSERT(MODE_X == lockState->getLockMode(globalId))
-            << "unexpected global lock mode " << modeName(lockState->getLockMode(globalId));
+        ASSERT(MODE_X == lockState->getLockMode(resourceIdGlobal))
+            << "unexpected global lock mode " << modeName(lockState->getLockMode(resourceIdGlobal));
         ASSERT_EQ(lockState->getLockMode(resourceIdReplicationStateTransitionLock), MODE_IX);
 
         // Downgrade global lock resource to MODE_IX to allow other write operations to make
         // progress.
-        lockState->downgrade(globalId, MODE_IX);
+        lockState->downgrade(resourceIdGlobal, MODE_IX);
         ASSERT_FALSE(lockState->isW());
         ASSERT(lockState->isWriteLocked());
-        ASSERT(MODE_IX == lockState->getLockMode(globalId))
-            << "unexpected global lock mode " << modeName(lockState->getLockMode(globalId));
+        ASSERT(MODE_IX == lockState->getLockMode(resourceIdGlobal))
+            << "unexpected global lock mode " << modeName(lockState->getLockMode(resourceIdGlobal));
         ASSERT_EQ(lockState->getLockMode(resourceIdReplicationStateTransitionLock), MODE_IX);
     }
 
@@ -364,8 +360,8 @@ TEST_F(DConcurrencyTestFixture,
     globalWrite = {};
     ASSERT_FALSE(lockState->isW());
     ASSERT_FALSE(lockState->isWriteLocked());
-    ASSERT(MODE_NONE == lockState->getLockMode(globalId))
-        << "unexpected global lock mode " << modeName(lockState->getLockMode(globalId));
+    ASSERT(MODE_NONE == lockState->getLockMode(resourceIdGlobal))
+        << "unexpected global lock mode " << modeName(lockState->getLockMode(resourceIdGlobal));
     ASSERT_EQ(lockState->getLockMode(resourceIdReplicationStateTransitionLock), MODE_NONE);
 }
 
@@ -375,8 +371,6 @@ TEST_F(DConcurrencyTestFixture,
     opCtx->swapLockState(stdx::make_unique<LockerImpl>());
     auto lockState = opCtx->lockState();
 
-    const ResourceId globalId(RESOURCE_GLOBAL, ResourceId::SINGLETON_GLOBAL);
-
     auto outerGlobalWrite = stdx::make_unique<Lock::GlobalWrite>(opCtx.get());
     auto innerGlobalWrite = stdx::make_unique<Lock::GlobalWrite>(opCtx.get());
     ASSERT_EQ(lockState->getLockMode(resourceIdReplicationStateTransitionLock), MODE_IX);
@@ -384,17 +378,17 @@ TEST_F(DConcurrencyTestFixture,
     {
         Lock::DBLock dbWrite(opCtx.get(), "db", MODE_IX);
         ASSERT(lockState->isW());
-        ASSERT(MODE_X == lockState->getLockMode(globalId))
-            << "unexpected global lock mode " << modeName(lockState->getLockMode(globalId));
+        ASSERT(MODE_X == lockState->getLockMode(resourceIdGlobal))
+            << "unexpected global lock mode " << modeName(lockState->getLockMode(resourceIdGlobal));
         ASSERT_EQ(lockState->getLockMode(resourceIdReplicationStateTransitionLock), MODE_IX);
 
         // Downgrade global lock resource to MODE_IX to allow other write operations to make
         // progress.
-        lockState->downgrade(globalId, MODE_IX);
+        lockState->downgrade(resourceIdGlobal, MODE_IX);
         ASSERT_FALSE(lockState->isW());
         ASSERT(lockState->isWriteLocked());
-        ASSERT(MODE_IX == lockState->getLockMode(globalId))
-            << "unexpected global lock mode " << modeName(lockState->getLockMode(globalId));
+        ASSERT(MODE_IX == lockState->getLockMode(resourceIdGlobal))
+            << "unexpected global lock mode " << modeName(lockState->getLockMode(resourceIdGlobal));
         ASSERT_EQ(lockState->getLockMode(resourceIdReplicationStateTransitionLock), MODE_IX);
     }
 
@@ -405,15 +399,15 @@ TEST_F(DConcurrencyTestFixture,
     innerGlobalWrite = {};
     ASSERT_FALSE(lockState->isW());
     ASSERT(lockState->isWriteLocked());
-    ASSERT(MODE_IX == lockState->getLockMode(globalId))
-        << "unexpected global lock mode " << modeName(lockState->getLockMode(globalId));
+    ASSERT(MODE_IX == lockState->getLockMode(resourceIdGlobal))
+        << "unexpected global lock mode " << modeName(lockState->getLockMode(resourceIdGlobal));
     ASSERT_EQ(lockState->getLockMode(resourceIdReplicationStateTransitionLock), MODE_IX);
 
     outerGlobalWrite = {};
     ASSERT_FALSE(lockState->isW());
     ASSERT_FALSE(lockState->isWriteLocked());
-    ASSERT(MODE_NONE == lockState->getLockMode(globalId))
-        << "unexpected global lock mode " << modeName(lockState->getLockMode(globalId));
+    ASSERT(MODE_NONE == lockState->getLockMode(resourceIdGlobal))
+        << "unexpected global lock mode " << modeName(lockState->getLockMode(resourceIdGlobal));
     ASSERT_EQ(lockState->getLockMode(resourceIdReplicationStateTransitionLock), MODE_NONE);
 }
 
diff --git a/src/mongo/db/concurrency/lock_manager_defs.h b/src/mongo/db/concurrency/lock_manager_defs.h
index 141b3ee4899..4d80fab87c5 100644
--- a/src/mongo/db/concurrency/lock_manager_defs.h
+++ b/src/mongo/db/concurrency/lock_manager_defs.h
@@ -153,13 +153,18 @@ enum LockResult {
  * ordering is consistent so deadlock cannot occur.
  */
 enum ResourceType {
-    /** Types used for special resources, use with a hash id from ResourceId::SingletonHashIds. */
     RESOURCE_INVALID = 0,
 
-    /**  Used for mode changes or global exclusive operations */
+    /** Parallel batch writer mutex */
+    RESOURCE_PBWM,
+
+    /** Replication state transition lock. */
+    RESOURCE_RSTL,
+
+    /**  Used for global exclusive operations */
     RESOURCE_GLOBAL,
 
-    /** Generic resources, used for multi-granularity locking, together with RESOURCE_GLOBAL */
+    /** Generic resources, used for multi-granularity locking, together with the above locks */
     RESOURCE_DATABASE,
     RESOURCE_COLLECTION,
     RESOURCE_METADATA,
@@ -174,8 +179,14 @@ enum ResourceType {
 /**
  * Maps the resource id to a human-readable string.
  */
-static const char* ResourceTypeNames[] = {
-    "Invalid", "Global", "Database", "Collection", "Metadata", "Mutex"};
+static const char* ResourceTypeNames[] = {"Invalid",
+                                          "ParallelBatchWriter",
+                                          "ReplicationStateTransition",
+                                          "Global",
+                                          "Database",
+                                          "Collection",
+                                          "Metadata",
+                                          "Mutex"};
 
 // Ensure we do not add new types without updating the names array.
 MONGO_STATIC_ASSERT((sizeof(ResourceTypeNames) / sizeof(ResourceTypeNames[0])) ==
@@ -197,17 +208,6 @@ class ResourceId {
     MONGO_STATIC_ASSERT(ResourceTypesCount <= (1 << resourceTypeBits));
 
 public:
-    /**
-     * Assign hash ids for special resources to avoid accidental reuse of ids. For ids used
-     * with the same ResourceType, the order here must be the same as the locking order.
-     */
-    enum SingletonHashIds {
-        SINGLETON_INVALID = 0,
-        SINGLETON_PARALLEL_BATCH_WRITER_MODE,
-        SINGLETON_REPLICATION_STATE_TRANSITION_LOCK,
-        SINGLETON_GLOBAL,
-    };
-
     ResourceId() : _fullHash(0) {}
     ResourceId(ResourceType type, StringData ns) : _fullHash(fullHash(type, hashStringData(ns))) {}
     ResourceId(ResourceType type, const std::string& ns)
@@ -283,25 +283,17 @@ extern const ResourceId resourceIdAdminDB;
 
 // Global lock. Every server operation, which uses the Locker must acquire this lock at least
 // once. See comments in the header file (begin/endTransaction) for more information.
-//
-// There are multiple locks with the "GLOBAL" type. This one is colloquially known as the global
-// lock.
 extern const ResourceId resourceIdGlobal;
 
-// Hardcoded resource id for ParallelBatchWriterMode. We use the same resource type
-// as resourceIdGlobal. This will also ensure the waits are reported as global, which
-// is appropriate. The lock will never be contended unless the parallel batch writers
-// must stop all other accesses globally. This resource must be locked before all other
-// resources (including resourceIdGlobal). Replication applier threads don't take this
-// lock.
-// TODO: Merge this with resourceIdGlobal
+// Hardcoded resource id for ParallelBatchWriterMode (PBWM). The lock will never be contended unless
+// the parallel batch writers must stop all other accesses globally. This resource must be locked
+// before all other resources (including resourceIdGlobal). Replication applier threads don't take
+// this lock.
 extern const ResourceId resourceIdParallelBatchWriterMode;
 
-// Hardcoded resource id for the ReplicationStateTransitionLock (RSTL). We use the same resource
-// type as resourceIdGlobal. This will also ensure the waits are reported as global, which is
-// appropriate. This lock is acquired in mode X for any replication state transition and is acquired
-// by all other reads and writes in mode IX. This lock is acquired after the PBWM but before the
-// resourceIdGlobal.
+// Hardcoded resource id for the ReplicationStateTransitionLock (RSTL). This lock is acquired in
+// mode X for any replication state transition and is acquired by all other reads and writes in mode
+// IX. This lock is acquired after the PBWM but before the resourceIdGlobal.
 extern const ResourceId resourceIdReplicationStateTransitionLock;
 
 /**
diff --git a/src/mongo/db/concurrency/lock_state.cpp b/src/mongo/db/concurrency/lock_state.cpp
index 75a6a771eea..44a5aa20ed0 100644
--- a/src/mongo/db/concurrency/lock_state.cpp
+++ b/src/mongo/db/concurrency/lock_state.cpp
@@ -56,7 +56,14 @@ MONGO_FAIL_POINT_DEFINE(failNonIntentLocksIfWaitNeeded);
 namespace {
 
 /**
- * Partitioned global lock statistics, so we don't hit the same bucket.
+ * Tracks global (across all clients) lock acquisition statistics, partitioned into multiple
+ * buckets to minimize concurrent access conflicts.
+ *
+ * Each client has a LockerId that monotonically increases across all client instances. The
+ * LockerId % 8 is used to index into one of 8 LockStats instances. These LockStats objects must be
+ * atomically accessed, so maintaining 8 that are indexed by LockerId reduces client conflicts and
+ * improves concurrent write access. A reader, to collect global lock statics for reporting, will
+ * sum the results of all 8 disjoint 'buckets' of stats.
  */
 class PartitionedInstanceWideLockStats {
     PartitionedInstanceWideLockStats(const PartitionedInstanceWideLockStats&) = delete;
@@ -117,7 +124,8 @@ const Milliseconds MaxWaitTime = Milliseconds(500);
 // Dispenses unique LockerId identifiers
 AtomicWord<unsigned long long> idCounter(0);
 
-// Partitioned global lock statistics, so we don't hit the same bucket
+// Tracks lock statistics across all Locker instances. Distributes stats across multiple buckets
+// indexed by LockerId in order to minimize concurrent access conflicts.
 PartitionedInstanceWideLockStats globalStats;
 
 }  // namespace
@@ -128,6 +136,8 @@ bool LockerImpl::_shouldDelayUnlock(ResourceId resId, LockMode mode) const {
             return false;
 
         case RESOURCE_GLOBAL:
+        case RESOURCE_PBWM:
+        case RESOURCE_RSTL:
         case RESOURCE_DATABASE:
         case RESOURCE_COLLECTION:
         case RESOURCE_METADATA:
@@ -395,7 +405,9 @@ bool LockerImpl::unlockGlobal() {
         // If we're here we should only have one reference to any lock. It is a programming
         // error for any lock used with multi-granularity locking to have more references than
         // the global lock, because every scope starts by calling lockGlobal.
-        if (it.key().getType() == RESOURCE_GLOBAL || it.key().getType() == RESOURCE_MUTEX) {
+        const auto resType = it.key().getType();
+        if (resType == RESOURCE_GLOBAL || resType == RESOURCE_PBWM || resType == RESOURCE_RSTL ||
+            resType == RESOURCE_MUTEX) {
             it.next();
         } else {
             invariant(_unlockImpl(&it));
@@ -749,9 +761,10 @@ bool LockerImpl::saveLockStateAndUnlock(Locker::LockSnapshot* stateOut) {
             continue;
 
         // We should never have to save and restore metadata locks.
-        invariant(RESOURCE_DATABASE == resId.getType() || RESOURCE_COLLECTION == resId.getType() ||
-                  (RESOURCE_GLOBAL == resId.getType() && isSharedLockMode(it->mode)) ||
-                  (resourceIdReplicationStateTransitionLock == resId && it->mode == MODE_IX));
+        invariant(RESOURCE_DATABASE == resType || RESOURCE_COLLECTION == resType ||
+                  (RESOURCE_GLOBAL == resType && isSharedLockMode(it->mode)) ||
+                  (RESOURCE_PBWM == resType && isSharedLockMode(it->mode)) ||
+                  (RESOURCE_RSTL == resType && it->mode == MODE_IX));
 
         // And, stuff the info into the out parameter.
         OneLock info;
@@ -837,7 +850,7 @@ LockResult LockerImpl::lockBegin(OperationContext* opCtx, ResourceId resId, Lock
     // Give priority to the full modes for Global, PBWM, and RSTL resources so we don't stall global
     // operations such as shutdown or stepdown.
     const ResourceType resType = resId.getType();
-    if (resType == RESOURCE_GLOBAL) {
+    if (resType == RESOURCE_GLOBAL || resType == RESOURCE_PBWM || resType == RESOURCE_RSTL) {
         if (mode == MODE_S || mode == MODE_X) {
             request->enqueueAtFront = true;
             request->compatibleFirst = true;
@@ -976,6 +989,7 @@ void LockerImpl::getFlowControlTicket(OperationContext* opCtx, LockMode lockMode
 }
 
 LockResult LockerImpl::lockRSTLBegin(OperationContext* opCtx, LockMode mode) {
+    invariant(mode == MODE_IX || mode == MODE_X);
     return lockBegin(opCtx, resourceIdReplicationStateTransitionLock, mode);
 }
 
@@ -1063,13 +1077,12 @@ void resetGlobalLockStats() {
     globalStats.reset();
 }
 
-// Definition for the hardcoded localdb and oplog collection info
+// Hardcoded resource IDs.
 const ResourceId resourceIdLocalDB = ResourceId(RESOURCE_DATABASE, StringData("local"));
 const ResourceId resourceIdOplog = ResourceId(RESOURCE_COLLECTION, StringData("local.oplog.rs"));
 const ResourceId resourceIdAdminDB = ResourceId(RESOURCE_DATABASE, StringData("admin"));
-const ResourceId resourceIdGlobal = ResourceId(RESOURCE_GLOBAL, ResourceId::SINGLETON_GLOBAL);
-const ResourceId resourceIdParallelBatchWriterMode =
-    ResourceId(RESOURCE_GLOBAL, ResourceId::SINGLETON_PARALLEL_BATCH_WRITER_MODE);
-const ResourceId resourceIdReplicationStateTransitionLock =
-    ResourceId(RESOURCE_GLOBAL, ResourceId::SINGLETON_REPLICATION_STATE_TRANSITION_LOCK);
+const ResourceId resourceIdGlobal = ResourceId(RESOURCE_GLOBAL, 1ULL);
+const ResourceId resourceIdParallelBatchWriterMode = ResourceId(RESOURCE_PBWM, 1ULL);
+const ResourceId resourceIdReplicationStateTransitionLock = ResourceId(RESOURCE_RSTL, 1ULL);
+
 }  // namespace mongo
diff --git a/src/mongo/db/concurrency/lock_state_test.cpp b/src/mongo/db/concurrency/lock_state_test.cpp
index 7c7f25418ff..76f51cf9a13 100644
--- a/src/mongo/db/concurrency/lock_state_test.cpp
+++ b/src/mongo/db/concurrency/lock_state_test.cpp
@@ -668,7 +668,6 @@ TEST_F(LockerImplTest, SharedLocksShouldTwoPhaseLockIsTrue) {
     // and S locks are postponed until endWriteUnitOfWork() is called. Mode IX and X locks always
     // participate in two-phased locking, regardless of the setting.
 
-    const ResourceId globalResId(RESOURCE_GLOBAL, ResourceId::SINGLETON_GLOBAL);
     const ResourceId resId1(RESOURCE_DATABASE, "TestDB1"_sd);
     const ResourceId resId2(RESOURCE_DATABASE, "TestDB2"_sd);
     const ResourceId resId3(RESOURCE_COLLECTION, "TestDB.collection3"_sd);
@@ -678,7 +677,7 @@ TEST_F(LockerImplTest, SharedLocksShouldTwoPhaseLockIsTrue) {
     locker.setSharedLocksShouldTwoPhaseLock(true);
 
     locker.lockGlobal(MODE_IS);
-    ASSERT_EQ(locker.getLockMode(globalResId), MODE_IS);
+    ASSERT_EQ(locker.getLockMode(resourceIdGlobal), MODE_IS);
 
     locker.lock(resourceIdReplicationStateTransitionLock, MODE_IS);
     ASSERT_EQ(locker.getLockMode(resourceIdReplicationStateTransitionLock), MODE_IS);
@@ -707,7 +706,7 @@ TEST_F(LockerImplTest, SharedLocksShouldTwoPhaseLockIsTrue) {
     ASSERT_EQ(locker.getLockMode(resourceIdReplicationStateTransitionLock), MODE_IS);
 
     ASSERT_FALSE(locker.unlockGlobal());
-    ASSERT_EQ(locker.getLockMode(globalResId), MODE_IS);
+    ASSERT_EQ(locker.getLockMode(resourceIdGlobal), MODE_IS);
 
     locker.endWriteUnitOfWork();
 
@@ -716,14 +715,13 @@ TEST_F(LockerImplTest, SharedLocksShouldTwoPhaseLockIsTrue) {
     ASSERT_EQ(locker.getLockMode(resId3), MODE_NONE);
     ASSERT_EQ(locker.getLockMode(resId4), MODE_NONE);
     ASSERT_EQ(locker.getLockMode(resourceIdReplicationStateTransitionLock), MODE_NONE);
-    ASSERT_EQ(locker.getLockMode(globalResId), MODE_NONE);
+    ASSERT_EQ(locker.getLockMode(resourceIdGlobal), MODE_NONE);
 }
 
 TEST_F(LockerImplTest, ModeIXAndXLockParticipatesInTwoPhaseLocking) {
     // Unlock on mode IX and X locks during a WUOW should always be postponed until
     // endWriteUnitOfWork() is called. Mode IS and S locks should unlock immediately.
 
-    const ResourceId globalResId(RESOURCE_GLOBAL, ResourceId::SINGLETON_GLOBAL);
     const ResourceId resId1(RESOURCE_DATABASE, "TestDB1"_sd);
     const ResourceId resId2(RESOURCE_DATABASE, "TestDB2"_sd);
     const ResourceId resId3(RESOURCE_COLLECTION, "TestDB.collection3"_sd);
@@ -732,7 +730,7 @@ TEST_F(LockerImplTest, ModeIXAndXLockParticipatesInTwoPhaseLocking) {
     LockerImpl locker;
 
     locker.lockGlobal(MODE_IX);
-    ASSERT_EQ(locker.getLockMode(globalResId), MODE_IX);
+    ASSERT_EQ(locker.getLockMode(resourceIdGlobal), MODE_IX);
 
     locker.lock(resourceIdReplicationStateTransitionLock, MODE_IX);
     ASSERT_EQ(locker.getLockMode(resourceIdReplicationStateTransitionLock), MODE_IX);
@@ -761,14 +759,14 @@ TEST_F(LockerImplTest, ModeIXAndXLockParticipatesInTwoPhaseLocking) {
     ASSERT_EQ(locker.getLockMode(resourceIdReplicationStateTransitionLock), MODE_IX);
 
     ASSERT_FALSE(locker.unlockGlobal());
-    ASSERT_EQ(locker.getLockMode(globalResId), MODE_IX);
+    ASSERT_EQ(locker.getLockMode(resourceIdGlobal), MODE_IX);
 
     locker.endWriteUnitOfWork();
 
     ASSERT_EQ(locker.getLockMode(resId2), MODE_NONE);
     ASSERT_EQ(locker.getLockMode(resId4), MODE_NONE);
     ASSERT_EQ(locker.getLockMode(resourceIdReplicationStateTransitionLock), MODE_NONE);
-    ASSERT_EQ(locker.getLockMode(globalResId), MODE_NONE);
+    ASSERT_EQ(locker.getLockMode(resourceIdGlobal), MODE_NONE);
 }
 
 TEST_F(LockerImplTest, RSTLUnlocksWithNestedLock) {
@@ -950,7 +948,6 @@ bool lockerInfoContainsLock(const Locker::LockerInfo& lockerInfo,
 }  // namespace
 
 TEST_F(LockerImplTest, GetLockerInfoShouldReportHeldLocks) {
-    const ResourceId globalId(RESOURCE_GLOBAL, ResourceId::SINGLETON_GLOBAL);
     const ResourceId dbId(RESOURCE_DATABASE, "TestDB"_sd);
     const ResourceId collectionId(RESOURCE_COLLECTION, "TestDB.collection"_sd);
 
@@ -964,7 +961,7 @@ TEST_F(LockerImplTest, GetLockerInfoShouldReportHeldLocks) {
     Locker::LockerInfo lockerInfo;
     locker.getLockerInfo(&lockerInfo, boost::none);
 
-    ASSERT(lockerInfoContainsLock(lockerInfo, globalId, MODE_IX));
+    ASSERT(lockerInfoContainsLock(lockerInfo, resourceIdGlobal, MODE_IX));
     ASSERT(lockerInfoContainsLock(lockerInfo, dbId, MODE_IX));
     ASSERT(lockerInfoContainsLock(lockerInfo, collectionId, MODE_X));
     ASSERT_EQ(3U, lockerInfo.locks.size());
@@ -975,7 +972,6 @@ TEST_F(LockerImplTest, GetLockerInfoShouldReportHeldLocks) {
 }
 
 TEST_F(LockerImplTest, GetLockerInfoShouldReportPendingLocks) {
-    const ResourceId globalId(RESOURCE_GLOBAL, ResourceId::SINGLETON_GLOBAL);
     const ResourceId dbId(RESOURCE_DATABASE, "TestDB"_sd);
     const ResourceId collectionId(RESOURCE_COLLECTION, "TestDB.collection"_sd);
 
@@ -994,7 +990,7 @@ TEST_F(LockerImplTest, GetLockerInfoShouldReportPendingLocks) {
     // Assert the held locks show up in the output of getLockerInfo().
     Locker::LockerInfo lockerInfo;
     conflictingLocker.getLockerInfo(&lockerInfo, boost::none);
-    ASSERT(lockerInfoContainsLock(lockerInfo, globalId, MODE_IS));
+    ASSERT(lockerInfoContainsLock(lockerInfo, resourceIdGlobal, MODE_IS));
     ASSERT(lockerInfoContainsLock(lockerInfo, dbId, MODE_IS));
     ASSERT(lockerInfoContainsLock(lockerInfo, collectionId, MODE_IS));
     ASSERT_EQ(3U, lockerInfo.locks.size());
diff --git a/src/mongo/db/concurrency/lock_stats.cpp b/src/mongo/db/concurrency/lock_stats.cpp
index 24e04f49450..f724c90a240 100644
--- a/src/mongo/db/concurrency/lock_stats.cpp
+++ b/src/mongo/db/concurrency/lock_stats.cpp
@@ -45,20 +45,16 @@ void LockStats<CounterType>::report(BSONObjBuilder* builder) const {
     // All indexing below starts from offset 1, because we do not want to report/account
     // position 0, which is a sentinel value for invalid resource/no lock.
     for (int i = 1; i < ResourceTypesCount; i++) {
-        _report(builder,
-                resourceTypeName(static_cast<ResourceType>(i)),
-                _stats[i],
-                static_cast<ResourceType>(i) == ResourceType::RESOURCE_GLOBAL);
+        _report(builder, resourceTypeName(static_cast<ResourceType>(i)), _stats[i]);
     }
 
-    _report(builder, "oplog", _oplogStats, false);
+    _report(builder, "oplog", _oplogStats);
 }
 
 template <typename CounterType>
 void LockStats<CounterType>::_report(BSONObjBuilder* builder,
-                                     const char* sectionName,
-                                     const PerModeLockStatCounters& stat,
-                                     const bool includeCanonicalGlobal) const {
+                                     const char* resourceTypeName,
+                                     const PerModeLockStatCounters& stat) const {
     std::unique_ptr<BSONObjBuilder> section;
 
     // All indexing below starts from offset 1, because we do not want to report/account
@@ -69,14 +65,11 @@ void LockStats<CounterType>::_report(BSONObjBuilder* builder,
         std::unique_ptr<BSONObjBuilder> numAcquires;
         for (int mode = 1; mode < LockModesCount; mode++) {
             long long value = CounterOps::get(stat.modeStats[mode].numAcquisitions);
-            if (includeCanonicalGlobal) {
-                value += CounterOps::get(_resourceIdGlobal.modeStats[mode].numAcquisitions);
-            }
 
             if (value > 0) {
                 if (!numAcquires) {
                     if (!section) {
-                        section.reset(new BSONObjBuilder(builder->subobjStart(sectionName)));
+                        section.reset(new BSONObjBuilder(builder->subobjStart(resourceTypeName)));
                     }
 
                     numAcquires.reset(new BSONObjBuilder(section->subobjStart("acquireCount")));
@@ -91,13 +84,10 @@ void LockStats<CounterType>::_report(BSONObjBuilder* builder,
         std::unique_ptr<BSONObjBuilder> numWaits;
         for (int mode = 1; mode < LockModesCount; mode++) {
             long long value = CounterOps::get(stat.modeStats[mode].numWaits);
-            if (includeCanonicalGlobal) {
-                value += CounterOps::get(_resourceIdGlobal.modeStats[mode].numWaits);
-            }
             if (value > 0) {
                 if (!numWaits) {
                     if (!section) {
-                        section.reset(new BSONObjBuilder(builder->subobjStart(sectionName)));
+                        section.reset(new BSONObjBuilder(builder->subobjStart(resourceTypeName)));
                     }
 
                     numWaits.reset(new BSONObjBuilder(section->subobjStart("acquireWaitCount")));
@@ -112,13 +102,10 @@ void LockStats<CounterType>::_report(BSONObjBuilder* builder,
         std::unique_ptr<BSONObjBuilder> timeAcquiring;
         for (int mode = 1; mode < LockModesCount; mode++) {
             long long value = CounterOps::get(stat.modeStats[mode].combinedWaitTimeMicros);
-            if (includeCanonicalGlobal) {
-                value += CounterOps::get(_resourceIdGlobal.modeStats[mode].combinedWaitTimeMicros);
-            }
             if (value > 0) {
                 if (!timeAcquiring) {
                     if (!section) {
-                        section.reset(new BSONObjBuilder(builder->subobjStart(sectionName)));
+                        section.reset(new BSONObjBuilder(builder->subobjStart(resourceTypeName)));
                     }
 
                     timeAcquiring.reset(
@@ -140,7 +127,6 @@ void LockStats<CounterType>::reset() {
 
     for (int mode = 0; mode < LockModesCount; mode++) {
         _oplogStats.modeStats[mode].reset();
-        _resourceIdGlobal.modeStats[mode].reset();
     }
 }
 
diff --git a/src/mongo/db/concurrency/lock_stats.h b/src/mongo/db/concurrency/lock_stats.h
index 6d186f55f65..d45b3b38864 100644
--- a/src/mongo/db/concurrency/lock_stats.h
+++ b/src/mongo/db/concurrency/lock_stats.h
@@ -38,7 +38,8 @@ class BSONObjBuilder;
 
 
 /**
- * Operations for manipulating the lock statistics abstracting whether they are atomic or not.
+ * Abstraction for manipulating the lock statistics, operating on either AtomicWord<long long> or
+ * int64_t, which the rest of the code in this file refers to as CounterType.
  */
 struct CounterOps {
     static int64_t get(const int64_t& counter) {
@@ -72,7 +73,10 @@ struct CounterOps {
 
 
 /**
- * Bundle of locking statistics values.
+ * Counts numAcquisitions, numWaits and combinedWaitTimeMicros values.
+ *
+ * Additionally supports appending or subtracting other LockStatCounters' values to or from its own;
+ * and can reset its own values to 0.
  */
 template <typename CounterType>
 struct LockStatCounters {
@@ -96,7 +100,7 @@ struct LockStatCounters {
         CounterOps::set(combinedWaitTimeMicros, 0);
     }
 
-
+    // The lock statistics we track.
     CounterType numAcquisitions;
     CounterType numWaits;
     CounterType combinedWaitTimeMicros;
@@ -106,6 +110,8 @@ struct LockStatCounters {
 /**
  * Templatized lock statistics management class, which can be specialized with atomic integers
  * for the global stats and with regular integers for the per-locker stats.
+ *
+ * CounterType allows the code to operate on both int64_t and AtomicWord<long long>
  */
 template <typename CounterType>
 class LockStats {
@@ -135,10 +141,6 @@ public:
             return _oplogStats.modeStats[mode];
         }
 
-        if (resId == resourceIdGlobal) {
-            return _resourceIdGlobal.modeStats[mode];
-        }
-
         return _stats[resId.getType()].modeStats[mode];
     }
 
@@ -161,12 +163,6 @@ public:
             LockStatCountersType& thisStats = _oplogStats.modeStats[mode];
             thisStats.append(otherStats);
         }
-
-        for (int mode = 0; mode < LockModesCount; ++mode) {
-            const OtherLockStatCountersType& otherStats = other._resourceIdGlobal.modeStats[mode];
-            LockStatCountersType& thisStats = _resourceIdGlobal.modeStats[mode];
-            thisStats.append(otherStats);
-        }
     }
 
     template <typename OtherType>
@@ -186,12 +182,6 @@ public:
             LockStatCountersType& thisStats = _oplogStats.modeStats[mode];
             thisStats.subtract(otherStats);
         }
-
-        for (int mode = 0; mode < LockModesCount; ++mode) {
-            const OtherLockStatCountersType& otherStats = other._resourceIdGlobal.modeStats[mode];
-            LockStatCountersType& thisStats = _resourceIdGlobal.modeStats[mode];
-            thisStats.subtract(otherStats);
-        }
     }
 
     void report(BSONObjBuilder* builder) const;
@@ -212,15 +202,13 @@ private:
 
 
     void _report(BSONObjBuilder* builder,
-                 const char* sectionName,
-                 const PerModeLockStatCounters& stat,
-                 const bool includeCanonicalGlobal) const;
+                 const char* resourceTypeName,
+                 const PerModeLockStatCounters& stat) const;
 
 
-    // Split the lock stats per resource type. Special-case the oplog and global lock so we can
-    // collect more detailed stats for it.
+    // Split the lock stats per resource type. Special-case the oplog so we can collect more
+    // detailed stats for it.
     PerModeLockStatCounters _stats[ResourceTypesCount];
-    PerModeLockStatCounters _resourceIdGlobal;
     PerModeLockStatCounters _oplogStats;
 };
 
diff --git a/src/mongo/db/concurrency/lock_stats_test.cpp b/src/mongo/db/concurrency/lock_stats_test.cpp
index 5e03af8c3e2..f2aa46e3a5c 100644
--- a/src/mongo/db/concurrency/lock_stats_test.cpp
+++ b/src/mongo/db/concurrency/lock_stats_test.cpp
@@ -147,7 +147,12 @@ TEST_F(LockStatsTest, Subtraction) {
 }
 
 namespace {
-void assertAcquisitionStats(ResourceId rid) {
+/**
+ * Locks 'rid' and then checks the global lock stat is reported correctly. Either the global lock is
+ * reported locked if 'rid' is the global lock resource, or unlocked if 'rid' is not the global lock
+ * resource.
+ */
+void assertGlobalAcquisitionStats(ResourceId rid) {
     resetGlobalLockStats();
 
     SingleThreadedLockStats stats;
@@ -177,20 +182,22 @@ void assertAcquisitionStats(ResourceId rid) {
 }  // namespace
 
 TEST_F(LockStatsTest, GlobalRetrievableSeparately) {
-    assertAcquisitionStats(resourceIdGlobal);
-    assertAcquisitionStats(resourceIdParallelBatchWriterMode);
-    assertAcquisitionStats(resourceIdReplicationStateTransitionLock);
+    assertGlobalAcquisitionStats(resourceIdGlobal);
+    assertGlobalAcquisitionStats(resourceIdParallelBatchWriterMode);
+    assertGlobalAcquisitionStats(resourceIdReplicationStateTransitionLock);
 }
 
-TEST_F(LockStatsTest, ServerStatusAggregatesAllGlobal) {
+TEST_F(LockStatsTest, ServerStatus) {
     resetGlobalLockStats();
 
+    // If there are no locks, nothing is reported.
     SingleThreadedLockStats stats;
     reportGlobalLockingStats(&stats);
     BSONObjBuilder builder;
     stats.report(&builder);
     ASSERT_EQUALS(0, builder.done().nFields());
 
+    // Take the global, PBWM and RSTL locks in MODE_IX to create acquisition stats for them.
     LockerImpl locker;
     locker.lockGlobal(LockMode::MODE_IX);
     locker.lock(resourceIdParallelBatchWriterMode, LockMode::MODE_IX);
@@ -200,12 +207,21 @@ TEST_F(LockStatsTest, ServerStatusAggregatesAllGlobal) {
     locker.unlock(resourceIdParallelBatchWriterMode);
     locker.unlockGlobal();
 
+    // Now the MODE_IX lock acquisitions should be reported, separately for each lock type.
     reportGlobalLockingStats(&stats);
     BSONObjBuilder builder2;
     stats.report(&builder2);
+    auto lockingStats = builder2.done();
     ASSERT_EQUALS(
-        3,
-        builder2.done().getObjectField("Global").getObjectField("acquireCount").getIntField("w"));
+        1, lockingStats.getObjectField("Global").getObjectField("acquireCount").getIntField("w"));
+    ASSERT_EQUALS(1,
+                  lockingStats.getObjectField("ParallelBatchWriter")
+                      .getObjectField("acquireCount")
+                      .getIntField("w"));
+    ASSERT_EQUALS(1,
+                  lockingStats.getObjectField("ReplicationStateTransition")
+                      .getObjectField("acquireCount")
+                      .getIntField("w"));
 }
 
 }  // namespace mongo