Don't attach finalizers to Handles in CommunicationHandle API #322
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We are now careful to not attach any Handle finalizers when creating
pipes for inter-process communication on Unix systems. Instead, the
handles are closed manually.
The finalizers were causing problems in situations such as the following:
- the parent creates a new pipe, e.g. pipe2([7,8]),
- the parent spawns a child process, and lets FD 8 be inherited by the child,
- the parent closes FD 8 (as it should),
- the parent opens FD 8 for some other purpose, e.g. for writing to a file,
- the finalizer for the Handle wrapping FD 8 runs, closing FD 8, even though
it is now in use for a completely different purpose.
This commit does not include a test, as the above bug is a bit difficult
to trigger.
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This seems sensible! |
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Yes, this seems like a reasonable approach. |
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We are now careful to not attach any finalizers to Handles when creating pipes for inter-process communication on Unix systems. Instead, the handles are closed manually.
The finalizers were causing problems in situations such as the following:
This PR does not include a test, as the above bug is a bit difficult to trigger. My reproducer for this bug was a test in the
cabal-installtestsuite; I can confirm that the bug no longer occurs with this patch.This PR bumps the process version to
1.6.21.0. After releasing it on Hackage, I would also recommend deprecating1.6.20.0.