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.

2 files changed, 12 insertions, 22 deletions

diff --git a/src/mongo/util/concurrency/thread_pool_test.cpp b/src/mongo/util/concurrency/thread_pool_test.cpp
index 30e5dbd0ddc..0b456c6abc1 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"
@@ -48,6 +50,7 @@
 
 namespace {
 using namespace mongo;
+using namespace fmt::literals;
 
 MONGO_INITIALIZER(ThreadPoolCommonTests)(InitializerContext*) {
     addTestsForThreadPool("ThreadPoolCommon",
@@ -256,29 +259,22 @@ DEATH_TEST_REGEX(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)]");
 }
 
 TEST(ThreadPoolTest, JoinAllRetiredThreads) {
diff --git a/src/mongo/util/thread_safety_context_test.cpp b/src/mongo/util/thread_safety_context_test.cpp
index 94d3c45d5b5..189bdc86ee0 100644
--- a/src/mongo/util/thread_safety_context_test.cpp
+++ b/src/mongo/util/thread_safety_context_test.cpp
@@ -29,7 +29,6 @@
 #include <vector>
 
 #include "mongo/stdx/thread.h"
-#include "mongo/unittest/barrier.h"
 #include "mongo/unittest/death_test.h"
 #include "mongo/unittest/unittest.h"
 #include "mongo/util/thread_safety_context.h"
@@ -78,15 +77,10 @@ DEATH_TEST_F(ThreadSafetyContextTest, CreateThreadsAfterForbidingMultiThreading,
 }
 
 DEATH_TEST_F(ThreadSafetyContextTest, ForbidMultiThreadingAfterCreatingThreads, "invariant") {
-    unittest::Barrier barrier(2);
+    auto thread = stdx::thread([]() {});
 
-    auto thread = stdx::thread([&]() mutable {
-        barrier.countDownAndWait();
-        sleepFor(Milliseconds(50));
-    });
-
-    // Wait for the thread to start before proceeding with the test
-    barrier.countDownAndWait();
+    // Wait for the thread to return before proceeding with the test
+    thread.join();
 
     ThreadSafetyContext::getThreadSafetyContext()->forbidMultiThreading();
     // Must never reach here or the test fails