Bug fix: KeyboardInterrupt while copying data from an mmapped region #467
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In the XShmGetImage backend, there was a window of time during which a KeyboardInterrupt (or other asynchronous exception) would cause cleanup of the MSS object to raise a different exception. This is one of the slower parts of this backend, so it's a time when asynchronous exceptions can hit pretty easily. While a Python library almost never can guarantee correctness following an asynchronous exception, ending a program with Ctrl-C is not uncommon. We can't guarantee correctness in all circumstances, and shouldn't try to. All this patch does is to avoid the exception that may be hard for an end user to understand. Instead, the top-level user code will now see the KeyboardInterrupt, and not the seemingly-unrelated cleanup exception.
BoboTiG
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Jan 28, 2026
* Bug fix: KeyboardInterrupt while copying data from an mmapped region In the XShmGetImage backend, there was a window of time during which a KeyboardInterrupt (or other asynchronous exception) would cause cleanup of the MSS object to raise a different exception. This is one of the slower parts of this backend, so it's a time when asynchronous exceptions can hit pretty easily. While a Python library almost never can guarantee correctness following an asynchronous exception, ending a program with Ctrl-C is not uncommon. We can't guarantee correctness in all circumstances, and shouldn't try to. All this patch does is to avoid the exception that may be hard for an end user to understand. Instead, the top-level user code will now see the KeyboardInterrupt, and not the seemingly-unrelated cleanup exception. * Switch to a simpler implementation I just learned that memoryviews can be used as context managers, and release their buffers at the end of that, instead of having to be GC'd.
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In the XShmGetImage backend, there was a window of time during which a KeyboardInterrupt (or other asynchronous exception) would cause cleanup of the MSS object to raise a different exception. This is one of the slower parts of this backend, so it's a time when asynchronous exceptions can hit pretty easily.
While a Python library almost never can guarantee correctness following an asynchronous exception, ending a program with Ctrl-C is not uncommon. We can't guarantee correctness in all circumstances, and shouldn't try to.
All this patch does is to avoid the exception that may be hard for an end user to understand. Instead, the top-level user code will now see the KeyboardInterrupt, and not the seemingly-unrelated cleanup exception.
Changes proposed in this PR
./check.shpassed