Symptom
Why are fewer traces generated than the number of requests sent?
On the Trace Query page in the ARMS console, the API list on the left shows that the /api/testing.json endpoint received 16 requests, but the trace details table on the right displays only 5 trace records (with durations of 653 ms, 582 ms, 491 ms, 342 ms, and 328 ms respectively).
Cause
The number of traces depends on the configured sampling rate.
You can view the sampling rate in the Sampling Settings section on the tab for your target application in the ARMS console. The default sampling rate is 10%, meaning only 10% of traces are collected.
Sampling rules:
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ARMS agent V3.x samples traces of error calls by default. ARMS agent V4.x samples traces of both error calls and exception calls by default.
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Traces for slow calls follow the same sampling policy as normal requests.