Add a note about potential subprocess perf impact #127
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| @@ -578,6 +578,10 @@ class SubprocessFixture(Fixture): | |||
| to either filter the subprocess pipes or use the ``--logfile`` argument to write the output | |||
| to a file in persistent storage. | |||
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| Nanaimo's output processing may cause performance impact to subprocesses if output is sent | |||
| from the subprocess faster than it can be processed by Nanaimo. In that case, the subprocess' | |||
| output must be redirected to a file in order to prevent Nanaimo from attempting to process it. | |||
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Hmm. I bet we could fix this by simply getting rid of the stdio pipes if no filters are provided. What do you think? Could you try that?
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That's a good idea. I'll give it a try but it might be a couple of days.
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@thirtytwobits I experimented with changing line 799 of fixtures.py to the following (effectively disabling logging if there are no filters). That breaks the test "test_subprocess_fixture_logfile", because no logfile is created, because nothing is logged, because the test doesn't provide any filters.
I think this is a pretty big breaking change (no more default logging unless filters are passed)--maybe we should add an explicit option to not subscribe to the output?
if stderr_filter or stdout_filter:
await self._wait_for_either_until_neither(
(proc.stdout if proc.stdout is not None else self._NoopStreamReader()),
(proc.stderr if proc.stderr is not None else self._NoopStreamReader()))
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