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100 lines
3.2 KiB
Python
100 lines
3.2 KiB
Python
# Monkey-patch os.fork() to produce a latency histogram on run completion.
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# Requires 'hdrhsitograms' PyPI module.
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from __future__ import print_function
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import os
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import resource
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import sys
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import time
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import ansible.plugins.callback
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try:
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import hdrh.histogram
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except ImportError:
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hdrh = None
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def get_fault_count(who=resource.RUSAGE_CHILDREN):
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ru = resource.getrusage(who)
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return ru.ru_minflt + ru.ru_majflt
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class CallbackModule(ansible.plugins.callback.CallbackBase):
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hist = None
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def v2_playbook_on_start(self, playbook):
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if self.hist is not None:
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return
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if hdrh and 'FORK_HISTOGRAM' in os.environ:
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self.hist = hdrh.histogram.HdrHistogram(1, int(1e6*60), 3)
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self.fork_latency_sum_usec = 0.0
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self.install()
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def install(self):
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self.faults_at_start = get_fault_count(resource.RUSAGE_SELF)
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self.run_start_time = time.time()
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self.real_fork = os.fork
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os.fork = self.my_fork
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self_fault_usec = 1.113664156753052
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child_fault_usec = 4.734975610975617
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dummy_heap_size = int(os.environ.get('FORK_STATS_FAKE_HEAP_MB', '0'))
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dummy_heap = 'x' * (dummy_heap_size * 1048576)
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def my_fork(self):
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# doesnt count last child, oh well
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now_faults = get_fault_count()
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t0 = time.time()
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try:
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return self.real_fork()
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finally:
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latency_usec = (1e6 * (time.time() - t0))
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self.fork_latency_sum_usec += latency_usec
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self.hist.record_value(latency_usec)
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def playbook_on_stats(self, stats):
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if hdrh is None or 'FORK_HISTOGRAM' not in os.environ:
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return
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self_faults = get_fault_count(resource.RUSAGE_SELF) - self.faults_at_start
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child_faults = get_fault_count()
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run_duration_sec = time.time() - self.run_start_time
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fault_wastage_usec = (
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((self.self_fault_usec * self_faults) +
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(self.child_fault_usec * child_faults))
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)
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fork_wastage = self.hist.get_total_count()
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all_wastage_usec = ((2*self.fork_latency_sum_usec) + fault_wastage_usec)
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print('--- Fork statistics ---')
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print('Post-boot run duration: %.02f ms, %d total forks' % (
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1000 * run_duration_sec,
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self.hist.get_total_count(),
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))
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print('Self faults during boot: %d, post-boot: %d, avg %d/child' % (
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self.faults_at_start,
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self_faults,
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self_faults / self.hist.get_total_count(),
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))
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print('Total child faults: %d, avg %d/child' % (
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child_faults,
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child_faults / self.hist.get_total_count(),
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))
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print('Est. wastage on faults: %d ms, forks+faults+waits: %d ms (%.2f%%)' % (
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fault_wastage_usec / 1000,
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all_wastage_usec / 1000,
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100 * (all_wastage_usec / (run_duration_sec * 1e6)),
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))
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print('99th%% fork latency: %.03f msec, max %d new tasks/sec' % (
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self.hist.get_value_at_percentile(99) / 1000.0,
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1e6 / self.hist.get_value_at_percentile(99),
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))
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self.hist.output_percentile_distribution(sys.stdout, 1000)
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print('--- End fork statistics ---')
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print()
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