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src: fix v8::CpuProfiler idle sampling #2324

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src: fix v8::CpuProfiler idle sampling #2324

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src: fix v8::CpuProfiler idle sampling 
Ensure that samples are evenly distributed, which is required for v8::CpuProfiler
users to work correctly (v8-profiler / node-inspector).
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Oleksandr Chekhovskyi committed Aug 28, 2015
commit 9ba84d84d16efc8dbd1f7e8d88b1b039737eed93
13 changes: 9 additions & 4 deletions src/node.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -3587,10 +3587,6 @@ inline void PlatformInit() {
RegisterSignalHandler(SIGINT, SignalExit, true);
RegisterSignalHandler(SIGTERM, SignalExit, true);

// Block SIGPROF signals when sleeping in epoll_wait/kevent/etc. Avoids the
// performance penalty of frequent EINTR wakeups when the profiler is running.
uv_loop_configure(uv_default_loop(), UV_LOOP_BLOCK_SIGNAL, SIGPROF);

// Raise the open file descriptor limit.
struct rlimit lim;
if (getrlimit(RLIMIT_NOFILE, &lim) == 0 && lim.rlim_cur != lim.rlim_max) {
Expand Down Expand Up @@ -3674,6 +3670,15 @@ void Init(int* argc,
}
}

#ifdef __POSIX__
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@thefourtheye thefourtheye Aug 7, 2015

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What will happen in Windows?

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@OleksandrChekhovskyi OleksandrChekhovskyi Aug 7, 2015

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Probably it will always collect samples during idle time (I have not tested Windows).
Note that the original code above was POSIX-only as well. It is moved here so that it can be conditional on the command line flag '--prof' (so only block SIGPROF if using v8.log-style profiling).

// Block SIGPROF signals when sleeping in epoll_wait/kevent/etc. Avoids the
// performance penalty of frequent EINTR wakeups when the profiler is running.
// Only do this for v8.log profiling, as it breaks v8::CpuProfiler users.
if (v8_is_profiling) {
uv_loop_configure(uv_default_loop(), UV_LOOP_BLOCK_SIGNAL, SIGPROF);
}
#endif

#if defined(NODE_HAVE_I18N_SUPPORT)
if (icu_data_dir == nullptr) {
// if the parameter isn't given, use the env variable.
Expand Down