void
TelemetryImpl::RecordChromeHang(uint32_t duration,
const Telemetry::HangStack &callStack,
SharedLibraryInfo &moduleMap)
{
MOZ_ASSERT(sTelemetry);
if (!sTelemetry->mCanRecord) {
return;
}
MutexAutoLock hangReportMutex(sTelemetry->mHangReportsMutex);
// Only report the modules which changed since the first hang report
if (sTelemetry->mHangReports.Length()) {
SharedLibraryInfo &firstModuleMap =
sTelemetry->mHangReports[0].moduleMap;
for (size_t i = 0; i < moduleMap.GetSize(); ++i) {
if (firstModuleMap.Contains(moduleMap.GetEntry(i))) {
moduleMap.RemoveEntries(i, i + 1);
--i;
}
}
}
HangReport newReport = { duration, callStack, moduleMap };
sTelemetry->mHangReports.AppendElement(newReport);
}
static void
GetChromeHangReport(Telemetry::HangStack &callStack, SharedLibraryInfo &moduleMap)
{
MOZ_ASSERT(winMainThreadHandle);
DWORD ret = ::SuspendThread(winMainThreadHandle);
if (ret == -1) {
callStack.Clear();
moduleMap.Clear();
return;
}
NS_StackWalk(ChromeStackWalker, 0, &callStack,
reinterpret_cast<uintptr_t>(winMainThreadHandle));
ret = ::ResumeThread(winMainThreadHandle);
if (ret == -1) {
callStack.Clear();
moduleMap.Clear();
return;
}
moduleMap = SharedLibraryInfo::GetInfoForSelf();
moduleMap.SortByAddress();
// Remove all modules not referenced by a PC on the stack
Telemetry::HangStack sortedStack = callStack;
sortedStack.Sort();
size_t moduleIndex = 0;
size_t stackIndex = 0;
bool unreferencedModule = true;
while (stackIndex < sortedStack.Length() && moduleIndex < moduleMap.GetSize()) {
uintptr_t pc = sortedStack[stackIndex];
SharedLibrary& module = moduleMap.GetEntry(moduleIndex);
uintptr_t moduleStart = module.GetStart();
uintptr_t moduleEnd = module.GetEnd() - 1;
if (moduleStart <= pc && pc <= moduleEnd) {
// If the current PC is within the current module, mark module as used
unreferencedModule = false;
++stackIndex;
} else if (pc > moduleEnd) {
if (unreferencedModule) {
// Remove module if no PCs within its address range
moduleMap.RemoveEntries(moduleIndex, moduleIndex + 1);
} else {
// Module was referenced on stack, but current PC belongs to later module
unreferencedModule = true;
++moduleIndex;
}
} else {
// PC does not belong to any module
++stackIndex;
}
}
// Clean up remaining unreferenced modules, i.e. module addresses > max(pc)
if (moduleIndex + 1 < moduleMap.GetSize()) {
moduleMap.RemoveEntries(moduleIndex + 1, moduleMap.GetSize());
}
}
virtual const CodeModule* GetModuleAtIndex(unsigned int aIndex) const
{
const SharedLibrary& lib = mLibs.GetEntry(aIndex);
mModule = new BasicCodeModule(lib.GetStart(), lib.GetEnd() - lib.GetStart(),
lib.GetName(), lib.GetBreakpadId(),
lib.GetName(), lib.GetBreakpadId(), "");
// Keep mModule valid until the next GetModuleAtIndex call.
return mModule;
}
std::string
GetSharedLibraryInfoString()
{
SharedLibraryInfo info = SharedLibraryInfo::GetInfoForSelf();
if (info.GetSize() == 0)
return "[]";
std::ostringstream os;
os << "[";
AddSharedLibraryInfoToStream(os, info.GetEntry(0));
for (size_t i = 1; i < info.GetSize(); i++) {
os << ",";
AddSharedLibraryInfoToStream(os, info.GetEntry(i));
}
os << "]";
return os.str();
}
virtual unsigned int module_count() const
{
return mLibs.GetSize();
}
void
ThreadMain(void*)
{
PR_SetCurrentThreadName("Hang Monitor");
MonitorAutoLock lock(*gMonitor);
// In order to avoid issues with the hang monitor incorrectly triggering
// during a general system stop such as sleeping, the monitor thread must
// run twice to trigger hang protection.
PRIntervalTime lastTimestamp = 0;
int waitCount = 0;
#ifdef REPORT_CHROME_HANGS
Telemetry::HangStack hangStack;
SharedLibraryInfo hangModuleMap;
#endif
while (true) {
if (gShutdown) {
return; // Exit the thread
}
// avoid rereading the volatile value in this loop
PRIntervalTime timestamp = gTimestamp;
PRIntervalTime now = PR_IntervalNow();
if (timestamp != PR_INTERVAL_NO_WAIT &&
now < timestamp) {
// 32-bit overflow, reset for another waiting period
timestamp = 1; // lowest legal PRInterval value
}
if (timestamp != PR_INTERVAL_NO_WAIT &&
timestamp == lastTimestamp &&
gTimeout > 0) {
++waitCount;
if (waitCount == 2) {
#ifdef REPORT_CHROME_HANGS
GetChromeHangReport(hangStack, hangModuleMap);
#else
PRInt32 delay =
PRInt32(PR_IntervalToSeconds(now - timestamp));
if (delay > gTimeout) {
MonitorAutoUnlock unlock(*gMonitor);
Crash();
}
#endif
}
}
else {
#ifdef REPORT_CHROME_HANGS
if (waitCount >= 2) {
PRUint32 hangDuration = PR_IntervalToSeconds(now - lastTimestamp);
Telemetry::RecordChromeHang(hangDuration, hangStack, hangModuleMap);
hangStack.Clear();
hangModuleMap.Clear();
}
#endif
lastTimestamp = timestamp;
waitCount = 0;
}
PRIntervalTime timeout;
if (gTimeout <= 0) {
timeout = PR_INTERVAL_NO_TIMEOUT;
}
else {
timeout = PR_MillisecondsToInterval(gTimeout * 500);
}
lock.Wait(timeout);
}
}
