Updated tests: cases with bugs or which cannot be run
with the cursor-protocol were excluded with
"--disable_cursor_protocol"/"--enable_cursor_protocol"
Fix for v.10.5
Update the description of each test case as to why it is
counted in the correct binlog_group_commit_trigger_* variable.
Updated rpl_parallel_multilevel2.test to identify that 3 groups
occur in statement and mixed replication and one group in row based
replication.
remove group_commit_reason_immediate
rename group_commit_reason_transaction to group_commit_trigger_lock_wait
rename group_commit_reason_usec to group_commit_trigger_timeout
rename group_commit_reason_count to group_commit_triggger_count
The following global status variables where added:
* binlog_group_commit_reason_count
* binlog_group_commit_reason_usec
* binlog_group_commit_reason_transaction
* binlog_group_commit_reason_immediate
binlog_group_commit_reason_count corresponds to group commits made by
virtue of the binlog_commit_wait_count variable.
binlog_group_commit_reason_usec corresponds to the binlog_commit_wait_usec
variable.
binlog_group_commit_reason_transaction is a result of ordered
transaction that need to occur in the same order on the slave and can't
be parallelised.
binlog_group_commit_reason_immediate is caused to prevent stalls with
row locks as described in log.cc:binlog_report_wait_for. This immediate
count is also counted a second time in binlog_group_commit_reason_transaction.
Overall binlog_group_commits = binlog_group_commit_reason_count +
binlog_group_commit_reason_usec + binlog_group_commit_reason_transaction
This work was funded thanks to Open Source Developers Club Australia.
Parallel replication (in 10.0 / "conservative" mode) relies on binlog group
commits to group transactions that can be safely run in parallel on the
slave. The --binlog-commit-wait-count and --binlog-commit-wait-usec options
exist to increase the number of commits per group. But in case of conflicts
between transactions, this can cause unnecessary delay and reduced througput,
especially on a slave where commit order is fixed.
This patch adds a heuristics to reduce this problem. When transaction T1 goes
to commit, it will first wait for N transactions to queue up for a group
commit. However, if we detect that another transaction T2 is waiting for a row
lock held by T1, then we will skip the wait and let T1 commit immediately,
releasing locks and let T2 continue.
On a slave, this avoids the unfortunate situation where T1 is waiting for T2
to join the group commit, but T2 is waiting for T1 to release locks, causing
no work to be done for the duration of the --binlog-commit-wait-usec timeout.
(The heuristic seems reasonable on the master as well, so it is enabled for
all transactions, not just replication transactions).
