SERVER-48346 Fix lifetime issues for barriers captured by reference

Extends the lifetime of barriers that are referenced by background
threads and their reference could outlive the barrier's owner.

(cherry picked from commit 3b7bc03a8f8b964769ff708674163b67ddd1a450)

2 files changed, 15 insertions, 13 deletions

diff --git a/src/mongo/executor/thread_pool_task_executor_test.cpp b/src/mongo/executor/thread_pool_task_executor_test.cpp
index b487cc87a41..40bf1c1249f 100644
--- a/src/mongo/executor/thread_pool_task_executor_test.cpp
+++ b/src/mongo/executor/thread_pool_task_executor_test.cpp
@@ -86,6 +86,9 @@ TEST_F(ThreadPoolExecutorTest, Schedule) {
     });
     barrier.countDownAndWait();
     ASSERT_OK(status1);
+    // Wait for the executor to stop to ensure the scheduled job does not outlive current scope.
+    executor.shutdown();
+    executor.join();
 }
 
 TEST_F(ThreadPoolExecutorTest, ScheduleAfterShutdown) {
@@ -112,6 +115,9 @@ TEST_F(ThreadPoolExecutorTest, OnEvent) {
     executor.signalEvent(event);
     barrier.countDownAndWait();
     ASSERT_OK(status1);
+    // Wait for the executor to stop to ensure the scheduled job does not outlive current scope.
+    executor.shutdown();
+    executor.join();
 }
 
 TEST_F(ThreadPoolExecutorTest, OnEventAfterShutdown) {
diff --git a/src/mongo/util/concurrency/thread_pool_test.cpp b/src/mongo/util/concurrency/thread_pool_test.cpp
index b57554add21..ff97ec92d50 100644
--- a/src/mongo/util/concurrency/thread_pool_test.cpp
+++ b/src/mongo/util/concurrency/thread_pool_test.cpp
@@ -32,8 +32,10 @@
 #include "mongo/platform/basic.h"
 
 #include <boost/optional.hpp>
+#include <fmt/format.h>
 
 #include "mongo/base/init.h"
+#include "mongo/platform/atomic_word.h"
 #include "mongo/platform/mutex.h"
 #include "mongo/stdx/condition_variable.h"
 #include "mongo/stdx/thread.h"
@@ -49,6 +51,7 @@
 
 namespace {
 using namespace mongo;
+using namespace fmt::literals;
 
 MONGO_INITIALIZER(ThreadPoolCommonTests)(InitializerContext*) {
     addTestsForThreadPool("ThreadPoolCommon",
@@ -254,29 +257,22 @@ DEATH_TEST(ThreadPoolTest,
 
 TEST_F(ThreadPoolTest, ThreadPoolRunsOnCreateThreadFunctionBeforeConsumingTasks) {
     unittest::Barrier barrier(2U);
-
-    bool onCreateThreadCalled = false;
-    std::string taskThreadName;
+    std::string journal;
     ThreadPool::Options options;
     options.threadNamePrefix = "mythread";
     options.maxThreads = 1U;
-    options.onCreateThread = [&onCreateThreadCalled,
-                              &taskThreadName](const std::string& threadName) {
-        onCreateThreadCalled = true;
-        taskThreadName = threadName;
+    options.onCreateThread = [&](const std::string& threadName) {
+        journal.append("[onCreate({})]"_format(threadName));
     };
 
     ThreadPool pool(options);
     pool.startup();
-
-    pool.schedule([&barrier](auto status) {
-        ASSERT_OK(status);
+    pool.schedule([&](auto status) {
+        journal.append("[Call({})]"_format(status.toString()));
         barrier.countDownAndWait();
     });
     barrier.countDownAndWait();
-
-    ASSERT_TRUE(onCreateThreadCalled);
-    ASSERT_EQUALS(options.threadNamePrefix + "0", taskThreadName);
+    ASSERT_EQUALS(journal, "[onCreate(mythread0)][Call(OK)]");
 }
 
 }  // namespace