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Previously, we trusted the OS not to report EEXIST unless we'd passed in IPC_CREAT | IPC_EXCL or O_CREAT | O_EXCL, as appropriate. Solaris's shm_open() can in fact do that, causing us to crash because we didn't ereport and then we blithely assumed the mapping was successful. Let's treat EEXIST just like any other error, unless we're actually trying to create a new segment. This applies to shm_open(), where this behavior has been seen, and also to the equivalent operations for our sysv and mmap modes just on principle. Based on the underlying reason for the error, namely contention on a lock file managed by Solaris librt for each distinct name, this problem is only likely to happen on 15 and later, because the new shared memory stats system produces shm_open() calls for the same path from potentially large numbers of backends concurrently during authentication. Earlier releases only shared memory segments between a small number of parallel workers under one Gather node. You could probably hit it if you tried hard enough though, and we should have been more defensive in the first place. Therefore, back-patch to all supported releases. Per build farm animal margay. This isn't the end of the story, though, it just changes random crashes into random "File exists" errors; more work needed for a green build farm. Reviewed-by: Robert Haas <robertmhaas@gmail.com> Discussion: https://postgr.es/m/CA%2BhUKGKqKrCV5xKWfh9rnm%3Do%3DDwZLTLtnsj_XpUi9g5%3DV%2B9oyg%40mail.gmail.com
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/.