def test_set_sample_rate_by_service(self):
cases = [{
"service:,env:": 1
}, {
"service:,env:": 1,
"service:mcnulty,env:dev": 0.33,
"service:postgres,env:dev": 0.7
}, {
"service:,env:": 1,
"service:mcnulty,env:dev": 0.25,
"service:postgres,env:dev": 0.5,
"service:redis,env:prod": 0.75
}]
tracer = get_dummy_tracer()
tracer.configure(sampler=AllSampler(), priority_sampling=True)
priority_sampler = tracer.priority_sampler
for case in cases:
priority_sampler.set_sample_rate_by_service(case)
rates = {}
for k, v in iteritems(priority_sampler._by_service_samplers):
rates[k] = v.sample_rate
assert case == rates, "%s != %s" % (case, rates)
# It's important to also test in reverse mode for we want to make sure key deletion
# works as well as key insertion (and doing this both ways ensures we trigger both cases)
cases.reverse()
for case in cases:
priority_sampler.set_sample_rate_by_service(case)
rates = {}
for k, v in iteritems(priority_sampler._by_service_samplers):
rates[k] = v.sample_rate
assert case == rates, "%s != %s" % (case, rates)
def test_sample_rate_deviation(self):
for sample_rate in [0.1, 0.25, 0.5, 1]:
tracer = get_dummy_tracer()
writer = tracer.writer
tracer.configure(sampler=AllSampler(), priority_sampling=True)
# We need to set the writer because tracer.configure overrides it,
# indeed, as we enable priority sampling, we must ensure the writer
# is priority sampling aware and pass it a reference on the
# priority sampler to send the feedback it gets from the agent
assert writer != tracer.writer, "writer should have been updated by configure"
tracer.writer = writer
tracer.priority_sampler.set_sample_rate(sample_rate)
random.seed(1234)
iterations = int(1e4 / sample_rate)
for i in range(iterations):
span = tracer.trace(i)
span.finish()
samples = writer.pop()
samples_with_high_priority = 0
for sample in samples:
if sample.get_metric(SAMPLING_PRIORITY_KEY) is not None:
if sample.get_metric(SAMPLING_PRIORITY_KEY) > 0:
samples_with_high_priority += 1
else:
assert 0 == sample.get_metric(
SAMPLING_PRIORITY_KEY
), "when priority sampling is on, priority should be 0 when trace is to be dropped"
# We must have at least 1 sample, check that it has its sample rate properly assigned
assert samples[0].get_metric(SAMPLE_RATE_METRIC_KEY) is None
# Less than 2% deviation when "enough" iterations (arbitrary, just check if it converges)
deviation = abs(samples_with_high_priority -
(iterations * sample_rate)) / (iterations *
sample_rate)
assert deviation < 0.02, "Deviation too high %f with sample_rate %f" % (
deviation, sample_rate)
def test_update_rate_by_service_sample_rates(self):
cases = [
{
'service:,env:': 1,
},
{
'service:,env:': 1,
'service:mcnulty,env:dev': 0.33,
'service:postgres,env:dev': 0.7,
},
{
'service:,env:': 1,
'service:mcnulty,env:dev': 0.25,
'service:postgres,env:dev': 0.5,
'service:redis,env:prod': 0.75,
},
]
tracer = get_dummy_tracer()
tracer.configure(sampler=AllSampler())
priority_sampler = tracer.priority_sampler
for case in cases:
priority_sampler.update_rate_by_service_sample_rates(case)
rates = {}
for k, v in iteritems(priority_sampler._by_service_samplers):
rates[k] = v.sample_rate
assert case == rates, '%s != %s' % (case, rates)
# It's important to also test in reverse mode for we want to make sure key deletion
# works as well as key insertion (and doing this both ways ensures we trigger both cases)
cases.reverse()
for case in cases:
priority_sampler.update_rate_by_service_sample_rates(case)
rates = {}
for k, v in iteritems(priority_sampler._by_service_samplers):
rates[k] = v.sample_rate
assert case == rates, '%s != %s' % (case, rates)
