gh-153279: Don't unlink another process's shared memory block on failed attach#153280
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gh-153279: Don't unlink another process's shared memory block on failed attach#153280uguraka wants to merge 1 commit into
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…n failed attach SharedMemory.__init__ called self.unlink() from its OSError cleanup handler unconditionally. On the attach path (create=False) this destroyed a block owned by another process when mmap() failed (e.g. ENOMEM). The cleanup now only closes the file descriptor and unlinks the block only when it was created in the failing call. Because the block has not been registered with the resource tracker yet at that point, it is unlinked directly to avoid a spurious UNREGISTER (which raised KeyError in the resource tracker on the create path).
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SharedMemory.__init__calledself.unlink()from itsOSErrorcleanuphandler unconditionally:
On the attach path (
create=False) this permanently destroyed a block ownedby another process when
mmap()failed (e.g.ENOMEMunder memory pressure),since
unlink()callsshm_unlink().The cleanup now only closes the file descriptor, and unlinks the block only
when it was created in the failing call. Because the block has not been
registered with the resource tracker at that point (
register()runs after thetry/except), it is unlinked directly rather than throughunlink(), whichavoids a spurious
UNREGISTERthat raisedKeyErrorin the resource trackeron the
create=Truepath.Added regression tests for both the attach and create failure paths; the attach
test fails without the fix.