This is an addition to original fix. Buildbot revealed another sporadic failure
in perfschema.threads_mysql test. Tests relies on data stored in
performance_schema.threads, while performing waits on
information_schema.processlist. These tables are not updated synchronously.
Fixed by performing waits on performance_schema.threads instead.
When a deadlock kill is detected inside the storage engine, the kill
is not done immediately, to avoid calling back into the storage engine
kill_query method with various lock subsystem mutexes held. Instead the
kill is queued and done later by a slave background thread.
This patch in preparation for fixing TokuDB optimistic parallel
replication, as well as for removing locking hacks in InnoDB/XtraDB in
10.2.
Signed-off-by: Kristian Nielsen <knielsen at knielsen-hq.org>
Permanently removed test case perfschema.aggregate.
The Performance Schema is generally lock-free, allowing for
race conditions that might arise from multi-threaded operation
which occasionally results in temporary and/or minor variances
when aggregating statistics. This test needs to be redesigned
to accommodate such variances.
Problem is that FLUSH TABLES WITH READ LOCK first blocks threads from
starting new commits, then waits for running commits to complete. But
in-order parallel replication needs commits to happen in a particular
order, so this can easily deadlock.
To fix this problem, this patch introduces a way to temporarily pause
the parallel replication worker threads. Before starting FTWRL, we let
all worker threads complete in-progress transactions, and then
wait. Then we proceed to take the global read lock. Once the lock is
obtained, we unpause the worker threads. Now commits are blocked from
starting by the global read lock, so the deadlock will no longer occur.
A few tests assumes that the CYCLE timer is always available,
which is not true on some platforms (e.g. ARM).
Fixing the tests not to reply on the CYCLE availability.
Moved Apc_target::destroy(), Apc_target::enable() and Apc_targe::disable()
definitions to my_apc.h so that they can be inlined.
Apc_targe::disable() now calls Apc_target::process_apc_requests() only if
there're APC requests. This saves one pthread_mutex_lock() call.
Overhead change:
Apc_target::disable 0.04% -> out of radar
Apc_target::enable 0.03% -> out of radar
Apc_target::process_apc_requests 0.02% -> out of radar
pthread_mutex_lock 0.43% -> 0.42%
pthread_mutex_unlock 0.26% -> 0.25%
