[WIP] Set OPENBLAS_NUM_THREADS by default#7177
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Unit Test ResultsSee test report for an extended history of previous test failures. This is useful for diagnosing flaky tests. 15 files ±0 15 suites ±0 6h 23m 48s ⏱️ - 11m 3s For more details on these failures, see this check. Results for commit 07c1fb4. ± Comparison against base commit 8f25111. |
crusaderky
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In #5098 we set a malloc trim threshold by default to more aggressively control memory trimming. also related #7177 At the same time, we included these default settings but didn't have incredibly solid arguments for it. It's been a long standing best practice when using dask to disable this nested parallelism. We haven't received a lot of user feedback about this. However, we had some internal reports of users who were struggling with this because this was quite unexpected behavior for them and non-trivial to debug for the ordinary end user. In apache/arrow#38389 (comment) this also suggests to negatively impact read performance of parquet tables. We should consider removing this again
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In https://docs.dask.org/en/stable/array-best-practices.html#avoid-oversubscribing-threads we recommend setting
to avoid oversubscribing worker threads.
Today we set
OMP_NUM_THREADSandMKL_NUM_THREADSby default (when using a nanny)distributed/distributed/distributed.yaml
Lines 191 to 193 in 6ac679e
So users get good defaults by default. Should we also set
OPENBLAS_NUM_THREADS?cc @crusaderky in case you have thoughts here