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# ==== Purpose ====
#
# This test will make many transactions to be grouped when binary logged
# and will assert that they used the lock_sidno less times than the amount
# of transactions * 2.
#
# Previous to BUG#24398760 fix, every transaction being committed would
# take the lock_sidno twice inside ordered_commit function:
# a) At the flush stage, to be assigned with a new GTID and take the ownership
# of the GTID;
# b) At the commit stage, to release the ownership of the GTID and to add the
# gtid to the GTID_EXECUTED set.
#
# So, a group committing 10 transactions would take the sidno_lock 20 times.
#
# According to the bug report, having about 300 threads committing small
# transactions would lead to groups of up to 90 transactions on high performance
# environments. This would mean that the system would have about 180 threads
# trying to lock the sidno_lock (90 at the flush stage, 90 at the commit stage).
#
# Even knowing that the threads would acquire the lock one by one at each stage,
# this might generate unnecessary overhead when the system is loaded.
#
# As the bug fix makes a group of transactions to acquire the sidno_lock only
# once at the flush stage and only once at the commit stage, this test case will
# create a group of 10 transactions to commit and will observe the performance
# schema data about the sidno_lock, asserting that the amount of "hits" on
# COUNT_STAR is 2:
# - 1 for the whole group on FLUSH stage;
# - 1 for the whole group on COMMIT stage.
#
# ==== Related Bugs and Worklogs ====
#
# BUG#24398760 GTIDS REDUCE PERFORMANCE ON WORKLOADS WITH MANY SMALL
# TRANSACTIONS
#
# This test case is binary log format agnostic
--source include/have_binlog_format_mixed.inc
--source include/have_binlog_order_commits.test
--source include/have_debug_sync.inc
# The amount of transactions that will be part of the commit group
--let $group_size= 10
--let $rpl_extra_connections_per_server= $group_size
--source include/master-slave.inc
--let $sync_point_timeout= 100
CREATE TABLE t1 (a INT);
# Cleanup performance schema table about locks
TRUNCATE performance_schema.events_waits_summary_by_instance;
# Execute the transactions up to the FLUSH stage
--let $i= 1
while ($i <= $group_size)
{
--let $statement_connection= server_1_$i
--let $sync_point= bgc_after_enrolling_for_flush_stage
--let $statement= INSERT INTO t1 VALUES ($i)
--let $auxiliary_connection= master
--source include/execute_to_sync_point.inc
--inc $i
}
# Let the transactions to execute from the FLUSH stage
--let $skip_reap= 1
--let $i= 1
while ($i <= $group_size)
{
--let $statement_connection= server_1_$i
--let $sync_point= bgc_after_enrolling_for_flush_stage
--let $statement= INSERT INTO t1 VALUES ($i)
--let $auxiliary_connection= master
--source include/execute_from_sync_point.inc
--inc $i
}
# Reap all the transactions
--let $i= 1
while ($i <= $group_size)
{
--let $rpl_connection_name= server_1_$i
--source include/rpl_connection.inc
--reap
--inc $i
}
# There will be one "hit" per transaction on FLUSH stage
--let $sidno_lock_count_star= 1
# There will be one "hit" per commit group on COMMIT stage
--inc $sidno_lock_count_star
--let $assert_text= The group commit should acquire sidno_lock for $sidno_lock_count_star times
--let $assert_cond= [ SELECT COUNT_STAR = $sidno_lock_count_star FROM performance_schema.events_waits_summary_by_instance WHERE EVENT_NAME = "wait/synch/mutex/sql/Gtid_state" AND COUNT_STAR > 0 ]
--let $extra_debug_info= Current COUNT_STAR for wait/synch/mutex/sql/Gtid_state
--let $extra_debug_eval= COUNT_STAR FROM performance_schema.events_waits_summary_by_instance WHERE EVENT_NAME = "wait/synch/mutex/sql/Gtid_state" AND COUNT_STAR > 0
--source include/assert.inc
# Cleanup
DROP TABLE t1;
--source include/rpl_end.inc
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