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|Reported by||Kim Carlsen|
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The following bug has been logged on the website: Bug reference: 15394 Logged by: Kim Carlsen Email address: (redacted) PostgreSQL version: 10.5 Operating system: Ubuntu 18.04 Description: It seems that the recovery thread(streaming replication) and sql queries against a postgresql hot standby can produce a deadlock. If you have conflicting statements running on master and slave, you can end up with queries on the slave waiting for locks of the recovery thread and the recovery thread waiting for locks on the sql thread. The locks are never resolved or any client aborted. This happens when using max_standby_streaming_delay=-1 The manual does state that the recovery thread can wait indefinitely on a SQL thread, but I would still expect dead locks to be detected and handled. How to reproduce: - Setup pgsql master/slave with streaming replication - On the slave "set max_standby_streaming_delay=-1" - Start a thread on master that does the following BEGIN; CREATE OR REPLACE VIEW va AS SELECT 1; CREATE OR REPLACE VIEW vb as SELECT 2; COMMIT; - Start multiple threads on the slave that does the following (with 5 workers running, a deadlock is produced within minutes) SELECT * FROM vb; SELECT * FROM va; Expected behaviour: The 5 threads will continue be able to query the views va, vb Observed behaviour: The 5 threads are blocked from reading the tables, after some time. They are never allowed access to the views before all queries are aborted and restarted. I have build a docker compose file to reproduce my observation. https://github.com/kimc78/postgresql-slave-deadlock This has been previously posted in pgsql-general and pgsql-bugs, my apologies for repeating the request.
|2018-09-21 09:21:12+00||=?utf-8?q?PG_Bug_reporting_form?=||BUG #15394: Conflict between recovery thread and client queries on a hot standby replica|