Make sure the main-thread TracingSamplerProfiler is explicitly destroyed

Otherwise, if it's destroyed through TLS, it can hang forever waiting
for a signal from the StackSamplingThread which never occurs.

This is going back to the behavior prior to
https://chromium-review.googlesource.com/c/chromium/src/+/1638578

R=ssid@chromium.org

Bug: 995323
Change-Id: I08863f5ee8ccd01c70b95bbce5fc28922dc06d1f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1761291Reviewed-by: Avi Drissman <avi@chromium.org>
Reviewed-by: ssid <ssid@chromium.org>
Commit-Queue: oysteine <oysteine@chromium.org>
Cr-Commit-Position: refs/heads/master@{#688622}

chrome/app/chrome_main_delegate.cc

@@ -634,7 +634,8 @@ bool ChromeMainDelegate::BasicStartupComplete(int* exit_code) {
   content::Profiling::ProcessStarted();
 
   // Setup tracing sampler profiler as early as possible at startup if needed.
-  tracing::TracingSamplerProfiler::CreateForCurrentThread();
+  tracing_sampler_profiler_ =
+      tracing::TracingSamplerProfiler::CreateOnMainThread();
 
 #if defined(OS_WIN) && !defined(CHROME_MULTIPLE_DLL_BROWSER)
   v8_crashpad_support::SetUp();

chrome/app/chrome_main_delegate.h

@@ -22,6 +22,10 @@ namespace base {
 class CommandLine;
 }
 
+namespace tracing {
+class TracingSamplerProfiler;
+}
+
 class ChromeContentBrowserClient;
 
 // Chrome implementation of ContentMainDelegate.
@@ -84,6 +88,8 @@ class ChromeMainDelegate : public content::ContentMainDelegate {
   std::unique_ptr<StartupData> startup_data_;
 #endif
 
+  std::unique_ptr<tracing::TracingSamplerProfiler> tracing_sampler_profiler_;
+
   DISALLOW_COPY_AND_ASSIGN(ChromeMainDelegate);
 };
 

chrome/browser/chrome_browser_main.cc

@@ -1171,7 +1171,7 @@ void ChromeBrowserMainParts::PostCreateThreads() {
 #if !defined(OS_ANDROID)
   base::PostTask(
       FROM_HERE, {BrowserThread::IO},
-      base::BindOnce(&tracing::TracingSamplerProfiler::CreateForCurrentThread));
+      base::BindOnce(&tracing::TracingSamplerProfiler::CreateOnChildThread));
 #endif
 
   tracing::SetupBackgroundTracingFieldTrial();

content/gpu/gpu_main.cc

@@ -362,7 +362,8 @@ int GpuMain(const MainFunctionParams& parameters) {
   gpu_process.set_main_thread(child_thread);
 
   // Setup tracing sampler profiler as early as possible.
-  tracing::TracingSamplerProfiler::CreateForCurrentThread();
+  std::unique_ptr<tracing::TracingSamplerProfiler> tracing_sampler_profiler =
+      tracing::TracingSamplerProfiler::CreateOnMainThread();
 
 #if defined(OS_ANDROID)
   base::trace_event::MemoryDumpManager::GetInstance()->RegisterDumpProvider(

content/renderer/renderer_main.cc

@@ -192,7 +192,8 @@ int RendererMain(const MainFunctionParams& parameters) {
                          std::move(main_thread_scheduler));
 
     // Setup tracing sampler profiler as early as possible.
-    tracing::TracingSamplerProfiler::CreateForCurrentThread();
+    auto tracing_sampler_profiler =
+        tracing::TracingSamplerProfiler::CreateOnMainThread();
 
     if (need_sandbox)
       should_run_loop = platform.EnableSandbox();

services/tracing/public/cpp/stack_sampling/tracing_sampler_profiler.cc

@@ -457,7 +457,14 @@ TracingSamplerProfiler::TracingProfileBuilder::GetCallstackIDAndMaybeEmit(
 }
 
 // static
-void TracingSamplerProfiler::CreateForCurrentThread() {
+std::unique_ptr<TracingSamplerProfiler>
+TracingSamplerProfiler::CreateOnMainThread() {
+  return std::make_unique<TracingSamplerProfiler>(
+      (base::PlatformThread::CurrentId()));
+}
+
+// static
+void TracingSamplerProfiler::CreateOnChildThread() {
   auto* slot = GetThreadLocalStorageProfilerSlot();
   if (slot->Get())
     return;
@@ -468,7 +475,7 @@ void TracingSamplerProfiler::CreateForCurrentThread() {
 }
 
 // static
-void TracingSamplerProfiler::DeleteForCurrentThreadForTesting() {
+void TracingSamplerProfiler::DeleteOnChildThreadForTesting() {
   auto* profiler = GetThreadLocalStorageProfilerSlot()->Get();
   if (profiler) {
     delete static_cast<TracingSamplerProfiler*>(profiler);

services/tracing/public/cpp/stack_sampling/tracing_sampler_profiler.h

@@ -93,19 +93,26 @@ class COMPONENT_EXPORT(TRACING_CPP) TracingSamplerProfiler {
     const bool should_enable_filtering_;
   };
 
-  // Sets up tracing sampling profiler on the current thread. The profiler will
-  // be stored in SequencedLocalStorageSlot and will be destroyed with the
-  // thread task runner.
-  static void CreateForCurrentThread();
+  // Creates sampling profiler on main thread. The profiler *must* be
+  // destroyed prior to process shutdown.
+  static std::unique_ptr<TracingSamplerProfiler> CreateOnMainThread();
+
+  // Sets up tracing sampling profiler on a child thread. The profiler will be
+  // stored in SequencedLocalStorageSlot and will be destroyed with the thread
+  // task runner.
+  static void CreateOnChildThread();
+
+  // Registers the TracingSamplerProfiler as a Perfetto data source
   static void RegisterDataSource();
 
   static void SetupStartupTracing();
 
   // For tests.
-  static void DeleteForCurrentThreadForTesting();
+  static void DeleteOnChildThreadForTesting();
   static void StartTracingForTesting(tracing::PerfettoProducer* producer);
   static void StopTracingForTesting();
 
+  explicit TracingSamplerProfiler(base::PlatformThreadId sampled_thread_id);
   virtual ~TracingSamplerProfiler();
 
   void StartTracing(std::unique_ptr<perfetto::TraceWriter> trace_writer,
@@ -113,8 +120,6 @@ class COMPONENT_EXPORT(TRACING_CPP) TracingSamplerProfiler {
   void StopTracing();
 
  private:
-  explicit TracingSamplerProfiler(base::PlatformThreadId sampled_thread_id);
-
   const base::PlatformThreadId sampled_thread_id_;
 
   base::Lock lock_;

services/tracing/public/cpp/stack_sampling/tracing_sampler_profiler_unittest.cc

@@ -249,29 +249,27 @@ class TestModule : public base::ModuleCache::Module {
 }  // namespace
 
 TEST_F(TracingSampleProfilerTest, OnSampleCompleted) {
-  TracingSamplerProfiler::CreateForCurrentThread();
+  auto profiler = TracingSamplerProfiler::CreateOnMainThread();
   BeginTrace();
   base::RunLoop().RunUntilIdle();
   WaitForEvents();
   EndTracing();
   base::RunLoop().RunUntilIdle();
   ValidateReceivedEvents();
-  TracingSamplerProfiler::DeleteForCurrentThreadForTesting();
 }
 
 TEST_F(TracingSampleProfilerTest, JoinRunningTracing) {
   BeginTrace();
-  TracingSamplerProfiler::CreateForCurrentThread();
+  auto profiler = TracingSamplerProfiler::CreateOnMainThread();
   base::RunLoop().RunUntilIdle();
   WaitForEvents();
   EndTracing();
   base::RunLoop().RunUntilIdle();
   ValidateReceivedEvents();
-  TracingSamplerProfiler::DeleteForCurrentThreadForTesting();
 }
 
 TEST_F(TracingSampleProfilerTest, TestStartupTracing) {
-  TracingSamplerProfiler::CreateForCurrentThread();
+  auto profiler = TracingSamplerProfiler::CreateOnMainThread();
   TracingSamplerProfiler::SetupStartupTracing();
   base::RunLoop().RunUntilIdle();
   WaitForEvents();
@@ -302,13 +300,12 @@ TEST_F(TracingSampleProfilerTest, TestStartupTracing) {
     EXPECT_LT(first_profile_ts,
               start_tracing_ts.since_origin().InMicroseconds());
   }
-  TracingSamplerProfiler::DeleteForCurrentThreadForTesting();
 }
 
 TEST_F(TracingSampleProfilerTest, JoinStartupTracing) {
   TracingSamplerProfiler::SetupStartupTracing();
   base::RunLoop().RunUntilIdle();
-  TracingSamplerProfiler::CreateForCurrentThread();
+  auto profiler = TracingSamplerProfiler::CreateOnMainThread();
   WaitForEvents();
   auto start_tracing_ts = TRACE_TIME_TICKS_NOW();
   BeginTrace();
@@ -337,15 +334,13 @@ TEST_F(TracingSampleProfilerTest, JoinStartupTracing) {
     EXPECT_LT(first_profile_ts,
               start_tracing_ts.since_origin().InMicroseconds());
   }
-  TracingSamplerProfiler::DeleteForCurrentThreadForTesting();
 }
 
 TEST_F(TracingSampleProfilerTest, SamplingChildThread) {
   base::Thread sampled_thread("sampling_profiler_test");
   sampled_thread.Start();
   sampled_thread.task_runner()->PostTask(
-      FROM_HERE,
-      base::BindOnce(&TracingSamplerProfiler::CreateForCurrentThread));
+      FROM_HERE, base::BindOnce(&TracingSamplerProfiler::CreateOnChildThread));
   BeginTrace();
   base::RunLoop().RunUntilIdle();
   WaitForEvents();
@@ -353,8 +348,7 @@ TEST_F(TracingSampleProfilerTest, SamplingChildThread) {
   ValidateReceivedEvents();
   sampled_thread.task_runner()->PostTask(
       FROM_HERE,
-      base::BindOnce(
-          &TracingSamplerProfiler::DeleteForCurrentThreadForTesting));
+      base::BindOnce(&TracingSamplerProfiler::DeleteOnChildThreadForTesting));
   base::RunLoop().RunUntilIdle();
 }