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Forward SIGALRM to original thread #192

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Merged
merged 1 commit into from
Nov 29, 2022
Merged

Forward SIGALRM to original thread #192

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20 changes: 19 additions & 1 deletion ext/stackprof/stackprof.c
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Original file line number Diff line number Diff line change
Expand Up @@ -125,6 +125,8 @@ static struct {
sample_time_t buffer_time;
VALUE frames_buffer[BUF_SIZE];
int lines_buffer[BUF_SIZE];

pthread_t target_thread;
} _stackprof;

static VALUE sym_object, sym_wall, sym_cpu, sym_custom, sym_name, sym_file, sym_line;
Expand Down Expand Up @@ -219,6 +221,7 @@ stackprof_start(int argc, VALUE *argv, VALUE self)
_stackprof.ignore_gc = ignore_gc;
_stackprof.metadata = metadata;
_stackprof.out = out;
_stackprof.target_thread = pthread_self();

if (raw) {
capture_timestamp(&_stackprof.last_sample_at);
Expand Down Expand Up @@ -721,7 +724,22 @@ stackprof_signal_handler(int sig, siginfo_t *sinfo, void *ucontext)
_stackprof.overall_signals++;

if (!_stackprof.running) return;
if (!ruby_native_thread_p()) return;

if (_stackprof.mode == sym_wall) {
// In "wall" mode, the SIGALRM signal will arrive at an arbitrary thread.
// In order to provide more useful results, especially under threaded web
// servers, we want to forward this signal to the original thread
// StackProf was started from.
// According to POSIX.1-2008 TC1 pthread_kill and pthread_self should be
// async-signal-safe.
if (pthread_self() != _stackprof.target_thread) {
pthread_kill(_stackprof.target_thread, sig);
return;
}
} else {
if (!ruby_native_thread_p()) return;
}

if (pthread_mutex_trylock(&lock)) return;

if (!_stackprof.ignore_gc && rb_during_gc()) {
Expand Down