MariaDB 10.4 was crashing when thread-handling was set to
pool-of-threads and wsrep was enabled.
There were two apparent reasons for the crash:
- Connection handling in threadpool_common.cc was missing calls to
control wsrep client state.
- Thread specific storage which contains thread variables (THR_KEY_mysys)
was not handled appropriately by wsrep patch when pool-of-threads
was configured.
This patch addresses the above issues in the following way:
- Wsrep client state open/close was moved in thd_prepare_connection() and
end_connection() to have common handling for one-thread-per-connection
and pool-of-threads.
- Thread local storage handling in wsrep patch was reworked by introducing
set of wsrep_xxx_threadvars() calls which replace calls to
THD store_globals()/reset_globals() and deal with thread handling
specifics internally.
Wsrep-lib was updated to version which relaxes internal concurrency
related sanity checks.
Rollback code from wsrep_rollback_process() was extracted to separate calls
for better readability.
Post rollback thread was removed as it was completely unused.
With wsrep_gtid_mode=ON, the appropriate commit hooks were not
called in all cases for applied streaming transactions.
As a fix, removed all special handling of commit order critical
section from Wsrep_high_priority_service and Wsrep_storage_service.
Now commit order critical section is always entered in ha_commit_trans().
Check for wsrep_run_commit_hook is now done in handler.cc, log.cc.
This makes it explicit that the transaction is an active wsrep
transaction which must go through commit hooks.
