TestGauge::test_time_block_decorator_with_label failure #942

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1. roidelapluie commented on Aug 8, 2023

   

   roidelapluie

   on Aug 8, 2023

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   What is alpha?
2. matoro commented on Aug 8, 2023

   

   matoro

   on Aug 8, 2023

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   What is alpha?

   It's a DEC Alpha machine! I've seen issues show up here before due to (1) low clock resolution and (2) race conditions exposed by its slow speed. If the log isn't enough to identify the problem, I have free shell access to all of the unusual machines I test on. Would provisioning an account so you can investigate directly help?
3. matoro commented on Oct 31, 2023

   

   matoro

   on Oct 31, 2023

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   One additional failure in 0.18.0.

   ================================================================== FAILURES ===================================================================
   _______________________________________________ TestGauge.test_time_block_decorator_with_label ________________________________________________
   
   self = <tests.test_core.TestGauge testMethod=test_time_block_decorator_with_label>
   
       def test_time_block_decorator_with_label(self):
           value = self.registry.get_sample_value
           self.assertEqual(None, value('g2', {'label1': 'foo'}))
           with self.gauge_with_label.time() as metric:
               metric.labels('foo')
   >       self.assertLess(0, value('g2', {'label1': 'foo'}))
   E       AssertionError: 0 not less than 0.0
   
   metric     = <prometheus_client.context_managers.Timer object at 0x2000403df90>
   self       = <tests.test_core.TestGauge testMethod=test_time_block_decorator_with_label>
   value      = <bound method CollectorRegistry.get_sample_value of <prometheus_client.registry.CollectorRegistry object at 0x2000403db10>>
   
   tests/test_core.py:255: AssertionError
   ___________________________________________________ TestMultiProcess.test_gauge_mostrecent ____________________________________________________
   
   self = <tests.test_multiprocess.TestMultiProcess testMethod=test_gauge_mostrecent>
   
       def test_gauge_mostrecent(self):
           g1 = Gauge('g', 'help', registry=None, multiprocess_mode='mostrecent')
           values.ValueClass = MultiProcessValue(lambda: 456)
           g2 = Gauge('g', 'help', registry=None, multiprocess_mode='mostrecent')
           g2.set(2)
           g1.set(1)
   >       self.assertEqual(1, self.registry.get_sample_value('g'))
   E       AssertionError: 1 != 2.0
   
   g1         = prometheus_client.metrics.Gauge(g)
   g2         = prometheus_client.metrics.Gauge(g)
   self       = <tests.test_multiprocess.TestMultiProcess testMethod=test_gauge_mostrecent>
    
   tests/test_multiprocess.py:194: AssertionError
   
4. csmarchbanks commented on Nov 1, 2023

   

   csmarchbanks

   on Nov 1, 2023

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   Both failures are possibly related to timing things, which as you say might be due to a low clock resolution. I don't really know much about alpha, and don't have time to try to debug it. I would be happy to accept a contribution to fix the test failures though!
5. nischita44 commented on Oct 9, 2026

   

   nischita44

   on Oct 9, 2026

   Last edited by nischita44

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   @fahadaldajani92’s approach for test_time_block_decorator_with_label makes sense, so I’ll leave that one to him. I’d like to take the other failure from this thread, test_gauge_mostrecent (and test_gauge_livemostrecent, which has the same issue). The two set() calls can get identical time.time() stamps on a coarse clock, and on a tie the collector keeps whichever .db file it reads first, so the result depends on filesystem order. I’d patch time.time in the tests with increasing values. Test-only change; I’ll open a separate PR unless someone objects.