[Python] Avoid SIGTTOU when importing readline from background process groups - #54
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[Python] Avoid SIGTTOU when importing readline from background process groups#54pzhan9 wants to merge 1 commit into
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July 20, 2026 22:48
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@LeiWang1999 is it possible that you could review this PR? It is to fix a bug described in this issue: #55 With this fix, we could revert this patch in torchtitian: pytorch/torchtitan#3950 thank you! |
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Motivation
Importing
readlinemay modify the controlling terminal withtcsetattr. As a result, when TVM is imported from a background process group, the kernel consequently sendsSIGTTOUand stops the process, which is undesired.Changes
Skip the import when this process group is background on its controlling TTY.
In addition, add PTY-based regression tests covering foreground pdb compatibility and background imports.
Testing
PYTHONPATH=$PWD/python pytest \ --confcutdir=tests/python/all-platform-minimal-test \ -q tests/python/all-platform-minimal-test/test_runtime_import.pyThe background test reproduces a stop from SIGTTOU on the base revision and passes with this change.