9be4ce4fa3
This test failed fairly reproducibly on some CLOBBER_CACHE_ALWAYS buildfarm animals. The cause seems to be that if a parallel worker is slow enough to reach its lock wait, it may not be released by the first deadlock check run, and then later deadlock checks might decide to unblock the d2 session instead of the d1 session, leaving us in an undetected deadlock state (since the isolationtester client is waiting for d1 to complete first). Fix by introducing an additional lock wait at the end of the d2a1 step, ensuring that the deadlock checker will recognize that d1 has to be unblocked before d2a1 completes. Also reduce max_parallel_workers_per_gather to 3 in this test. With the default max_worker_processes value, we were only getting one parallel worker for the d2a1 step, which is not the case I hoped to test. We should get 3 for d1a2 and 2 for d2a1, as the code stands; and maybe 3 for d2a1 if somebody figures out why the last parallel worker slot isn't free already. Discussion: https://postgr.es/m/22195.1566077308@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/.