[issue29988] with statements are not ensuring that __exit__ is called if __enter__ succeeds

[Nick Coghlan]

Nick Coghlan <ncoghlan at gmail.com> added the comment:

It's also not unique to with statements - it applies to all finally clauses. The longstanding workaround when deterministic cleanup is absolutely critical has been to run the "real" application in a subthread, and devote the main thread to gracefully terminating the subthread when requested.

When cleanup is critical, but doing it in a deterministic order is less so, __del__ methods are often used to fill the gap (although they too can be interrupted by a subsequent Ctrl-C).

I also realized that allowing infinite loops in cleanup code to ignore Ctrl-C may actually be a tolerable outcome: in the worst case, users can still escalate to Ctrl-Break/kill -9/Force stop/etc and pull the entire OS process out from under the interpreter. It's not good, but may be worth it in order to better handle users pressing Ctrl-C multiple times.

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<https://bugs.python.org/issue29988>
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