Fix two tests that fail on a heavily-loaded machine #38825
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One test in this file sets the timeout to 100ms and expects an easy
example to complete within that amount of time. It can still fail,
though, if the machine is under load:
File "src/sage/parallel/decorate.py", line 519, in
sage.parallel.decorate.fork
Failed example:
g(5, m=5)
Expected:
8
Got:
Killing subprocess 62130 with input ((5,), {'m': 5}) which
took too long
8
This example isn't really the purpose of the doctest -- its intent is
to show that there are hard examples that will NOT complete in
100ms. (That is much easier to do.) All things considered, we are
better off just dropping this one flaky example.
The test we have for start_workers() is doing a bit more than
that. It's starting two threads that each print something, sleep for a
bit, and then print something else. To check the expected output, we
are basically guessing how long it will take these threads to run, and
on a very heavily-loaded machine, we can guess wrong:
File "src/sage/parallel/map_reduce.py", line 1149, in
sage.parallel.map_reduce.RESetMapReduce.start_workers
Failed example:
sleep(float(1.5))
Expected:
Finished: ...
Finished: ...
Got:
Finished: 2
(We were expecting both threads to finish within 1.5s, but only one
did.)
To make this a bit more robust, we eliminate the sleep() and
subsequent print inside of the threads. As a result, we need only make
one guess: how long it will take the threads to start. And for that we
now go overkill and wait 5s.
|
Documentation preview for this PR (built with commit a181883; changes) is ready! 🎉 |
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tobiasdiez
approved these changes
Oct 19, 2024
vbraun
pushed a commit
to vbraun/sage
that referenced
this pull request
Oct 23, 2024
The commit messages explain each change in detail, but tl;dr these two
tests fail for me when the machine is under heavy load because they are
guessing how long it will take some computation to complete and the
guess is wrong.
URL: sagemath#38825
Reported by: Michael Orlitzky
Reviewer(s): Tobias Diez
tornaria
reviewed
Oct 27, 2024
| ....: return [] | ||
| sage: S = RESetMapReduce(roots=[1, 2], children=children) | ||
| sage: S.setup_workers(2) | ||
| sage: S.start_workers(); sleep(float(0.4)) | ||
| sage: S.start_workers(); sleep(float(5)) # long time |
There was a problem hiding this comment.
The # long time label causes a test failure in the cleanup section, when running tests in non-long mode.
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The commit messages explain each change in detail, but tl;dr these two tests fail for me when the machine is under heavy load because they are guessing how long it will take some computation to complete and the guess is wrong.