rtc::Event::Wait(kForever): Print stack trace when we deadlock
After being stuck "forever" (3 seconds) waiting for an event to
trigger, log the stack trace of the current thread to aid debugging of
the deadlock.
Bug: webrtc:10308
Change-Id: I04852f191027294d7e7a7f5e63de4c6c7fdd6326
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/128342
Commit-Queue: Karl Wiberg <kwiberg@webrtc.org>
Reviewed-by: Magnus Jedvert <magjed@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#27263}diff --git a/sdk/android/native_unittests/stacktrace/stacktrace_unittest.cc b/sdk/android/native_unittests/stacktrace/stacktrace_unittest.cc
index f71f5d9..4ea3c9f 100644
--- a/sdk/android/native_unittests/stacktrace/stacktrace_unittest.cc
+++ b/sdk/android/native_unittests/stacktrace/stacktrace_unittest.cc
@@ -200,6 +200,22 @@
thread.Stop();
}
+class LookoutLogSink final : public rtc::LogSink {
+ public:
+ explicit LookoutLogSink(std::string look_for)
+ : look_for_(std::move(look_for)) {}
+ void OnLogMessage(const std::string& message) override {
+ if (message.find(look_for_) != std::string::npos) {
+ when_found_.Set();
+ }
+ }
+ rtc::Event& WhenFound() { return when_found_; }
+
+ private:
+ const std::string look_for_;
+ rtc::Event when_found_;
+};
+
} // namespace
TEST(Stacktrace, TestCurrentThread) {
@@ -223,6 +239,7 @@
// Stack traces originating from kernel space does not include user space stack
// traces for ARM 32.
#ifdef WEBRTC_ARCH_ARM64
+
TEST(Stacktrace, TestRtcEvent) {
TestStacktrace(absl::make_unique<RtcEventDeadlock>());
}
@@ -230,7 +247,33 @@
TEST(Stacktrace, TestRtcCriticalSection) {
TestStacktrace(absl::make_unique<RtcCriticalSectionDeadlock>());
}
+
#endif
+TEST(Stacktrace, TestRtcEventDeadlockDetection) {
+ // Start looking for the expected log output.
+ LookoutLogSink sink(/*look_for=*/"Probable deadlock");
+ rtc::LogMessage::AddLogToStream(&sink, rtc::LS_WARNING);
+
+ // Start a thread that waits for an event.
+ rtc::Event ev;
+ rtc::PlatformThread thread(
+ [](void* arg) {
+ auto* ev = static_cast<rtc::Event*>(arg);
+ ev->Wait(rtc::Event::kForever);
+ },
+ &ev, "TestRtcEventDeadlockDetection");
+ thread.Start();
+
+ // The message should appear after 3 sec. We'll wait up to 10 sec in an
+ // attempt to not be flaky.
+ EXPECT_TRUE(sink.WhenFound().Wait(10000));
+
+ // Unblock the thread and shut it down.
+ ev.Set();
+ thread.Stop();
+ rtc::LogMessage::RemoveLogToStream(&sink);
+}
+
} // namespace test
} // namespace webrtc