Reviewers: Søren Gjesse,
Description:
Fix issue 410: test-log/ProfLazyMode flakinness under Linux.
I found two causes of flakinness:
- SIGPROF signal isn't delivered to a process;
- Profiler thread (the one that retrieves tick events from
the queue and writes to log) doesn't get a CPU;
Both are fixed.
The script from bug description with run count increased to 200 runs
without any test failures.
OS X and Windows are unaffected because they don't use signals
mechanism.
BUG=http://code.google.com/p/v8/issues/detail?id=410
TEST=see bug description
Please review this at http://codereview.chromium.org/159406
Affected files:
M test/cctest/test-log.cc
Index: test/cctest/test-log.cc
diff --git a/test/cctest/test-log.cc b/test/cctest/test-log.cc
index
f3f7efc710b99091c6e1e268acfc12ff09477c5f..1d5471b3490e3568b5be72ae27a8ec2bc626ab60
100644
--- a/test/cctest/test-log.cc
+++ b/test/cctest/test-log.cc
@@ -144,6 +144,26 @@ class LoggerTestHelper : public AllStatic {
using v8::internal::LoggerTestHelper;
+// Under Linux, we need to check if signals were delivered to avoid false
+// positives. Under other platforms profiling is done via a high-priority
+// thread, so this case never happen.
+static bool wasSigProfReceived = true;
+#ifdef __linux__
+
+#include <signal.h>
+#include <unistd.h>
+
+struct sigaction oldSigProfHandler;
+
+static void SigProfSignalHandler(int signal, siginfo_t* info, void*
context) {
+ if (signal != SIGPROF) return;
+ wasSigProfReceived = true;
+ oldSigProfHandler.sa_sigaction(signal, info, context);
+}
+
+#endif // __linux__
+
+
static int CheckThatProfilerWorks(int log_pos) {
Logger::ResumeProfiler();
CHECK(LoggerTestHelper::IsSamplerActive());
@@ -160,6 +180,18 @@ static int CheckThatProfilerWorks(int log_pos) {
const char* code_creation = "\ncode-creation,"; // eq. to
/^code-creation,/
CHECK_NE(NULL, strstr(buffer.start(), code_creation));
+#ifdef __linux__
+ // Intercept SIGPROF handler to make sure that the test process
+ // had received it. Under load, system can defer it causing test failure.
+ // It is important to execute this after 'ResumeProfiler'.
+ wasSigProfReceived = false;
+ struct sigaction sa;
+ sa.sa_sigaction = SigProfSignalHandler;
+ sigemptyset(&sa.sa_mask);
+ sa.sa_flags = SA_SIGINFO;
+ CHECK_EQ(0, sigaction(SIGPROF, &sa, &oldSigProfHandler));
+#endif // __linux__
+
// Force compiler to generate new code by parametrizing source.
EmbeddedVector<char, 100> script_src;
i::OS::SNPrintF(script_src,
@@ -170,6 +202,8 @@ static int CheckThatProfilerWorks(int log_pos) {
const double end_time = i::OS::TimeCurrentMillis() + 200;
while (i::OS::TimeCurrentMillis() < end_time) {
CompileAndRunScript(script_src.start());
+ // Yield CPU to give Profiler thread a chance to process ticks.
+ i::OS::Sleep(1);
}
Logger::PauseProfiler();
@@ -189,7 +223,8 @@ static int CheckThatProfilerWorks(int log_pos) {
buffer[log_size] = '\0';
const char* tick = "\ntick,";
CHECK_NE(NULL, strstr(buffer.start(), code_creation));
- CHECK_NE(NULL, strstr(buffer.start(), tick));
+ const bool ticksFound = strstr(buffer.start(), tick) != NULL;
+ CHECK_EQ(wasSigProfReceived, ticksFound);
return log_pos;
}
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