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[PROF-10422] Fix flaky GVL profiling integration spec #3936

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Sep 20, 2024
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[PROF-10422] Fix flaky GVL profiling integration spec #3936

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13 changes: 11 additions & 2 deletions spec/datadog/profiling/collectors/cpu_and_wall_time_worker_spec.rb
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Original file line number Diff line number Diff line change
Expand Up @@ -449,16 +449,25 @@
samples = samples_for_thread(
samples_from_pprof_without_gc_and_overhead(recorder.serialize!),
background_thread_affected_by_gvl_contention
)
).sort_by { |s| s.labels.fetch(:end_timestamp_ns) }

# Because the background_thread_affected_by_gvl_contention starts BEFORE the profiler, the first few samples
# will have an unknown state because the profiler may have missed the beginning of the Waiting for GVL
#
# So that the below assertions make sense (and are not flaky), we drop these first few samples from our
# consideration
missed_by_profiler_time =
samples.take_while { |s| s.labels[:state] == "unknown" }.sum { |sample| sample.values.fetch(:"wall-time") }

waiting_for_gvl_samples = samples.select { |sample| sample.labels[:state] == "waiting for gvl" }
total_time = samples.sum { |sample| sample.values.fetch(:"wall-time") }
total_time = samples.sum { |sample| sample.values.fetch(:"wall-time") } - missed_by_profiler_time
waiting_for_gvl_time = waiting_for_gvl_samples.sum { |sample| sample.values.fetch(:"wall-time") }

expect(waiting_for_gvl_samples.size).to be > 0

# The background thread should spend almost all of its time waiting to run (since when it gets to run
# it just passes and starts waiting)
expect(total_time).to be >= 200_000_000 # This test should run for at least 200ms, which is how long we sleep for
expect(waiting_for_gvl_time).to be < total_time
expect(waiting_for_gvl_time).to be_within(5).percent_of(total_time)

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