Test parallellization uses a stupid strategy

[ndossche]

Description

When running ./run-test.php with the -j argument, all the tests are scheduled to the workers before even running them. This means that if you have a worker which finishes all its tests quickly it'll sit idle even if there are many more other tests to run. One can observe this often because at the end of a test run the number of concurrent working test runners drops quickly.

PHP Version

8.4+

Operating System

N/A

[iluuu1994]

Another dumb thing that has bitten me before: When running tests without -j, tests are printed to the console before they are executed (without --no-progress). With -j, they are printed after.

One can observe this often because at the end of a test run the number of concurrent working test runners drops quickly.

One note though is that many of the last tests are marked as CONFLICTS: all. So they are intentionally unparallelized.

[ndossche]

One note though is that many of the last tests are marked as CONFLICTS: all. So they are intentionally unparallelized.

Yes. I was in particular looking at the OpenSSL tests, which has a CONFLICTS file but does no longer seem necessary, after removing that the number of concurrent workers still drop pretty quickly.