SERVER-42971 Restore original thread name upon ThreadClient destruction

3 files changed, 25 insertions, 0 deletions

diff --git a/src/mongo/db/client.cpp b/src/mongo/db/client.cpp
index 6982ad9e9db..7da46be32df 100644
--- a/src/mongo/db/client.cpp
+++ b/src/mongo/db/client.cpp
@@ -188,12 +188,14 @@ ThreadClient::ThreadClient(StringData desc,
                            ServiceContext* serviceContext,
                            transport::SessionHandle session) {
     invariantNoCurrentClient();
+    _originalThreadName = ThreadName::get(ThreadContext::get());
     Client::initThread(desc, serviceContext, std::move(session));
 }
 
 ThreadClient::~ThreadClient() {
     invariant(currentClient);
     currentClient.reset(nullptr);
+    ThreadName::set(ThreadContext::get(), _originalThreadName);
 }
 
 Client* ThreadClient::get() const {
diff --git a/src/mongo/db/client.h b/src/mongo/db/client.h
index 67b8ed959d5..e64c6b24d34 100644
--- a/src/mongo/db/client.h
+++ b/src/mongo/db/client.h
@@ -335,6 +335,9 @@ public:
     Client& operator*() const {
         return *get();
     }
+
+private:
+    boost::intrusive_ptr<ThreadName> _originalThreadName;
 };
 
 /**
diff --git a/src/mongo/db/thread_client_test.cpp b/src/mongo/db/thread_client_test.cpp
index 6c700a3a741..08f448c61eb 100644
--- a/src/mongo/db/thread_client_test.cpp
+++ b/src/mongo/db/thread_client_test.cpp
@@ -87,5 +87,25 @@ TEST_F(ThreadClientTest, TestAlternativeClientRegion) {
 
     ASSERT_TRUE(haveClient());
 }
+
+/**
+ * This test asserts that original thread names are restored after a ThreadClient object
+ * goes out of scope.
+ */
+TEST_F(ThreadClientTest, TestThreadName) {
+    ASSERT_FALSE(haveClient());
+    const auto originalThreadName = getThreadName();
+
+    {
+        ThreadClient threadClient("MyThreadClient", getGlobalServiceContext());
+        ASSERT_TRUE(haveClient());
+        // The instatiation of ThreadClient should have changed this thread name
+        ASSERT_NE(originalThreadName, getThreadName());
+    }
+
+    ASSERT_FALSE(haveClient());
+    // The original name for this thread should have been restored.
+    ASSERT_EQ(originalThreadName, getThreadName());
+}
 }  // namespace
 }  // namespace mongo