001a573a20
Just as backends must clean up their shared memory state (releasing lwlocks, buffer pins, etc.) before exiting, they must also perform any similar cleanups related to dynamic shared memory segments they have mapped before unmapping those segments. So add a mechanism to ensure that. Existing on_shmem_exit hooks include both "user level" cleanup such as transaction abort and removal of leftover temporary relations and also "low level" cleanup that forcibly released leftover shared memory resources. On-detach callbacks should run after the first group but before the second group, so create a new before_shmem_exit function for registering the early callbacks and keep on_shmem_exit for the regular callbacks. (An earlier draft of this patch added an additional argument to on_shmem_exit, but that had a much larger footprint and probably a substantially higher risk of breaking third party code for no real gain.) Patch by me, reviewed by KaiGai Kohei and Andres Freund. |
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