Before this fix, the test performance_schema.relaylog would fail
with sporadic failures related to statistics on update_cond.
The reason for these failures is that thread scheduling makes
impossible to predict if instrumented conditions will be used on not.
The fix is to relax the test case, to not collect statistics about:
- wait/synch/cond/sql/MYSQL_BIN_LOG::update_cond
- wait/synch/cond/sql/MYSQL_RELAY_LOG::update_cond
Before this fix, all the performance schema instrumentation for both the binary log
and the relay log would use the following instruments:
- wait/io/file/sql/binlog
- wait/io/file/sql/binlog_index
- wait/synch/mutex/sql/MYSQL_BIN_LOG::LOCK_index
- wait/synch/cond/sql/MYSQL_BIN_LOG::update_cond
This instrumentation is too general and can be more specific.
With this fix, the binlog instrumentation is identical,
and the relay log instrumentation is changed to:
- wait/io/file/sql/relaylog
- wait/io/file/sql/relaylog_index
- wait/synch/mutex/sql/MYSQL_RELAY_LOG::LOCK_index
- wait/synch/cond/sql/MYSQL_RELAY_LOG::update_cond
With this change, the performance instrumentation for the binary log and the relay log,
which share the same structure but have different uses, is more detailed.
This is especially important for hosts in the middle of a replication chain,
that are both masters (binlog) and slaves (relaylog).
