shell: fix hang when a tool command backgrounds a child process#2462
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dgageot merged 1 commit intodocker:mainfrom Apr 18, 2026
Merged
shell: fix hang when a tool command backgrounds a child process#2462dgageot merged 1 commit intodocker:mainfrom
dgageot merged 1 commit intodocker:mainfrom
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When a shell command backgrounds a grandchild (e.g. `docker run ... &`), the grandchild inherits the stdout/stderr pipe fds created by exec.Cmd for non-*os.File writers. cmd.Wait() then blocks until EOF on those pipes, which never comes while the grandchild holds them open — making the tool call hang until the configured timeout (observed wedging an eval run for minutes after the agent ran a detached `docker run`). Set cmd.WaitDelay to 500ms in runNativeCommand so that once the direct shell child has exited, Go force-closes the pipe read ends and Wait() returns promptly. The grandchild is left untouched — exactly what the user's `&` intended. Add two regression tests covering the plain backgrounded-child case and the detached (setsid) variant where the process-group kill fallback cannot rescue us. Assisted-By: docker-agent
krissetto
approved these changes
Apr 18, 2026
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When a shell command backgrounds a grandchild (e.g.
docker run ... &), the grandchild inherits the stdout/stderr pipe fds created by exec.Cmd for non-*os.File writers. cmd.Wait() then blocks until EOF on those pipes, which never comes while the grandchild holds them open — making the tool call hang until the configured timeout (observed wedging an eval run for minutes after the agent ran a detacheddocker run).Set cmd.WaitDelay to 500ms in runNativeCommand so that once the direct shell child has exited, Go force-closes the pipe read ends and Wait() returns promptly. The grandchild is left untouched — exactly what the user's
&intended.Add two regression tests covering the plain backgrounded-child case and the detached (setsid) variant where the process-group kill fallback cannot rescue us.
Assisted-By: docker-agent