Pablo Galindo Salgado <pablogsal@gmail.com> added the comment: Bisecting between 3.7.0(good) and 3.7.1(bad) with the code in my previous commit points to: 97f998a4dfd6db6d867f446daa62445d0782bf39 is the first bad commit commit 97f998a4dfd6db6d867f446daa62445d0782bf39 Author: Miss Islington (bot) <31488909+miss-islington@users.noreply.github.com> Date: Tue Oct 2 14:17:04 2018 -0700 bpo-34172: multiprocessing.Pool leaks resources after being deleted (GH-8450) (GH-9676) Fix a reference issue inside multiprocessing.Pool that caused the pool to remain alive if it was deleted without being closed or terminated explicitly. (cherry picked from commit 97bfe8d3ebb0a54c8798f57555cb4152f9b2e1d0) Co-authored-by: tzickel <tzickel@users.noreply.github.com> :040000 040000 90e0af29e82d0fcc1c1d7e19b3659f9602596e3e d997cfb00c1c44bbd87ce15edfd391203362a1d7 M Lib :040000 040000 6aa4273821c2c563ea69370a59284ed48576416f b6d46f14b6bb36cc5ae62b3ca74025c24d683bb5 M Misc bisect run success ---------- _______________________________________ Python tracker <report@bugs.python.org> <https://bugs.python.org/issue34172> _______________________________________