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Use more accurate profiling on Ruby 3.1 and fix async-signal-safety #172

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Merged
tenderlove merged 2 commits into from
Feb 16, 2022
Merged

Use more accurate profiling on Ruby 3.1 and fix async-signal-safety #172

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b2f5f7a
Add include for ruby/version.h
jhawthorn Feb 15, 2022
7a8e4ca
Avoid unsafe mallocs inside signals
jhawthorn Feb 15, 2022
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69 changes: 58 additions & 11 deletions ext/stackprof/stackprof.c
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Original file line number Diff line number Diff line change
Expand Up @@ -7,6 +7,7 @@
**********************************************************************/

#include <ruby/ruby.h>
#include <ruby/version.h>
#include <ruby/debug.h>
#include <ruby/st.h>
#include <ruby/io.h>
Expand Down Expand Up @@ -125,6 +126,9 @@ static struct {

VALUE fake_frame_names[TOTAL_FAKE_FRAMES];
VALUE empty_string;

int buffer_count;
sample_time_t buffer_time;
VALUE frames_buffer[BUF_SIZE];
int lines_buffer[BUF_SIZE];
} _stackprof;
Expand Down Expand Up @@ -593,9 +597,17 @@ stackprof_record_sample_for_stack(int num, uint64_t sample_timestamp, int64_t ti
}
}

// buffer the current profile frames
// This must be async-signal-safe
// Returns immediately if another set of frames are already in the buffer
void
stackprof_record_sample()
stackprof_buffer_sample(void)
{
if (_stackprof.buffer_count > 0) {
// Another sample is already pending
return;
}

uint64_t start_timestamp = 0;
int64_t timestamp_delta = 0;
int num;
Expand All @@ -605,12 +617,16 @@ stackprof_record_sample()
start_timestamp = timestamp_usec(&t);
timestamp_delta = delta_usec(&t, &_stackprof.last_sample_at);
}

num = rb_profile_frames(0, sizeof(_stackprof.frames_buffer) / sizeof(VALUE), _stackprof.frames_buffer, _stackprof.lines_buffer);
stackprof_record_sample_for_stack(num, start_timestamp, timestamp_delta);

_stackprof.buffer_count = num;
_stackprof.buffer_time.timestamp_usec = start_timestamp;
_stackprof.buffer_time.delta_usec = timestamp_delta;
}

void
stackprof_record_gc_samples()
stackprof_record_gc_samples(void)
{
int64_t delta_to_first_unrecorded_gc_sample = 0;
uint64_t start_timestamp = 0;
Expand Down Expand Up @@ -660,20 +676,47 @@ stackprof_record_gc_samples()
_stackprof.unrecorded_gc_sweeping_samples = 0;
}

// record the sample previously buffered by stackprof_buffer_sample
static void
stackprof_gc_job_handler(void *data)
stackprof_record_buffer(void)
{
stackprof_record_sample_for_stack(_stackprof.buffer_count, _stackprof.buffer_time.timestamp_usec, _stackprof.buffer_time.delta_usec);

// reset the buffer
_stackprof.buffer_count = 0;
}

static void
stackprof_sample_and_record(void)
{
stackprof_buffer_sample();
stackprof_record_buffer();
}

static void
stackprof_job_record_gc(void *data)
{
if (!_stackprof.running) return;

stackprof_record_gc_samples();
}

#ifdef USE_POSTPONED_JOB
static void
stackprof_job_sample_and_record(void *data)
{
if (!_stackprof.running) return;

stackprof_sample_and_record();
}
#endif

static void
stackprof_job_handler(void *data)
stackprof_job_record_buffer(void *data)
{
if (!_stackprof.running) return;

stackprof_record_sample();
stackprof_record_buffer();
}

static void
Expand All @@ -695,12 +738,16 @@ stackprof_signal_handler(int sig, siginfo_t *sinfo, void *ucontext)
_stackprof.unrecorded_gc_sweeping_samples++;
}
_stackprof.unrecorded_gc_samples++;
rb_postponed_job_register_one(0, stackprof_gc_job_handler, (void*)0);
rb_postponed_job_register_one(0, stackprof_job_record_gc, (void*)0);
} else {
#ifdef USE_POSTPONED_JOB
rb_postponed_job_register_one(0, stackprof_job_handler, (void*)0);
rb_postponed_job_register_one(0, stackprof_job_sample_and_record, (void*)0);
#else
stackprof_job_handler(0);
// Buffer a sample immediately, if an existing sample exists this will
// return immediately
stackprof_buffer_sample();
// Enqueue a job to record the sample
rb_postponed_job_register_one(0, stackprof_job_record_buffer, (void*)0);
#endif
}
pthread_mutex_unlock(&lock);
Expand All @@ -712,7 +759,7 @@ stackprof_newobj_handler(VALUE tpval, void *data)
_stackprof.overall_signals++;
if (RTEST(_stackprof.interval) && _stackprof.overall_signals % NUM2LONG(_stackprof.interval))
return;
stackprof_job_handler(0);
stackprof_sample_and_record();
}

static VALUE
Expand All @@ -722,7 +769,7 @@ stackprof_sample(VALUE self)
return Qfalse;

_stackprof.overall_signals++;
stackprof_job_handler(0);
stackprof_sample_and_record();
return Qtrue;
}

Expand Down