Start tests in sorted order also with multiple threads#141
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Since #119, each test is bound to its own task at spawn time, and all tasks race to acquire the semaphore. With a single thread tasks happen to reach the semaphore in spawn order, but with multiple threads the acquisition order is arbitrary, defeating the descending-historical- duration sort (#139). Instead, hand out tests in sorted order at acquisition time, via an atomic fetch-add index claimed only once a task holds a semaphore slot and a worker. Fixes #139. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
giordano
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Jul 2, 2026
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To demonstrate that this PR does solve #139, in this CI run I reverted the fix introduced in this PR, but only kept running the CI jobs with multiple Julia threads: in 11 out of 20 jobs, the tests introduced in #140 failed, as expected. Tests are instead all green when running Julia with multiple threads and applying the proposed fix. |
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This seems to also work for me! |
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Ok, I verified the new tests would occasionally fail before this PR, when running Julia with multiple threads, so this is ready to go from my side. |
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Since #119, each test is bound to its own task at spawn time, and all tasks race to acquire the semaphore. With a single thread tasks happen to reach the semaphore in spawn order, but with multiple threads the acquisition order is arbitrary, defeating the descending-historical- duration sort (#139).
Instead, hand out tests in sorted order at acquisition time, via an atomic fetch-add index claimed only once a task holds a semaphore slot and a worker.
Fixes #139. @christiangnrd can you please test this PR? It does seem to work for me, tests introduced in #140 now pass when using multiple Julia threads, which instead very frequently currently fail, as explained in #140 (comment).