sjaakola fb32a71fde MDEV-41385 wsrep_sync_wait has no effect after COM_CHANGE_USER ...

Also reported as: https://github.com/mariadb-corporation/galera/issues/613.

THD::cleanup() cleared THD::wsrep_client_thread. Besides connection
close, THD::cleanup() is also called from THD::change_user() when
handling COM_CHANGE_USER and COM_RESET_CONNECTION. THD::init() does
not set the flag back, and the only place that sets it is
thd_prepare_connection(). After either command the session was no
longer treated as a wsrep client connection: WSREP_CLIENT() returned
false for the rest of the session.

As a result wsrep_sync_wait was silently ignored, so causal reads
could return stale data. Such connections were also skipped by
wsrep_close_client_connections() and
wsrep_wait_committing_connections_close(). Connection pools issue
COM_RESET_CONNECTION whenever a connection is reused, so in practice
most pooled sessions were affected.

Fix by moving the reset of wsrep_client_thread from THD::cleanup()
to end_connection(), after wsrep_close().

The galera.galera_change_user test is extended to do a causal read
on a fresh connection, after COM_CHANGE_USER and after
COM_RESET_CONNECTION. Each read must increase the provider's
wsrep_causal_reads status counter.

2026-10-05 13:29:33 +03:00

50 KiB

Raw Permalink Blame History

View Raw