profiler: document/test that Start restarts the profiler #1805
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Start will first stop the profiler if it is already running, and the re-start it with the given configuration. This behaviour is not documented. It is also not tested--the current test suite passes if Start is changed to return early when the profiler is already active. It is possible that there are apps out there which rely on this behavior (some of our internal apps do), and it would be a breaking change for these apps to make Start do nothing if the profiler is already started. Given that there isn't a strong reason to change the behavior otherwise, we should document it and make sure it's actually tested. This commit adds a test to lock in this behavior. It also removes the TestStartStopIdempotent test. This test made no assertions, and at any rate Start was not idempotent to begin with.
felixge
approved these changes
Mar 15, 2023
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What does this PR do?
Document that Start will restart the profiler with the given configuration if
the profiler was already running. Add a test to lock in this behavior.
This PR also removes the TestStartStopIdempotent test. This test made no
assertions, and at any rate Start was not idempotent to begin with.
Motivation
Start will first stop the profiler if it is already running, and the
re-start it with the given configuration. This behavior is not
documented. It is also not tested--the current test suite passes if
Start is changed to return early when the profiler is already active.
It is possible that there are apps out there which rely on this behavior
(some of our internal apps do), and it would be a breaking change for
these apps to make Start do nothing if the profiler is already started.
Given that there isn't a strong reason to change the behavior otherwise,
we should document it and make sure it's actually tested.
Describe how to test/QA your changes
See the unit test.
Reviewer's Checklist
Triagemilestone is set.