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The logic around shm_mq_detach was a few bricks shy of a load, because (contrary to the comments for shm_mq_attach) all it did was update the shared shm_mq state. That left us leaking a bit of process-local memory, but much worse, the on_dsm_detach callback for shm_mq_detach was still armed. That means that whenever we ultimately detach from the DSM segment, we'd run shm_mq_detach again for already-detached, possibly long-dead queues. This accidentally fails to fail today, because we only ever re-use a shm_mq's memory for another shm_mq, and multiple detach attempts on the last such shm_mq are fairly harmless. But it's gonna bite us someday, so let's clean it up. To do that, change shm_mq_detach's API so it takes a shm_mq_handle not the underlying shm_mq. This makes the callers simpler in most cases anyway. Also fix a few places in parallel.c that were just pfree'ing the handle structs rather than doing proper cleanup. Back-patch to v10 because of the risk that the revenant shm_mq_detach callbacks would cause a live bug sometime. Since this is an API change, it's too late to do it in 9.6. (We could make a variant patch that preserves API, but I'm not excited enough to do that.) Discussion: https://postgr.es/m/8670.1504192177@sss.pgh.pa.us
PostgreSQL Database Management System ===================================== This directory contains the source code distribution of the PostgreSQL database management system. PostgreSQL is an advanced object-relational database management system that supports an extended subset of the SQL standard, including transactions, foreign keys, subqueries, triggers, user-defined types and functions. This distribution also contains C language bindings. PostgreSQL has many language interfaces, many of which are listed here: https://www.postgresql.org/download See the file INSTALL for instructions on how to build and install PostgreSQL. That file also lists supported operating systems and hardware platforms and contains information regarding any other software packages that are required to build or run the PostgreSQL system. Copyright and license information can be found in the file COPYRIGHT. A comprehensive documentation set is included in this distribution; it can be read as described in the installation instructions. The latest version of this software may be obtained at https://www.postgresql.org/download/. For more information look at our web site located at https://www.postgresql.org/.