I think I finally found the problem, managed to reproduce locally using a
sleep in the test case to simulate the particular race condition that causes
the test to fail often in Buildbot.
The test starts an ALTER TABLE that does repair by sort in one thread, then
another thread waits for the sort to be visible in SHOW PROCESSLIST and runs a
SHOW statement in parallel.
The problem happens when the sort manages to run to completion before the
other thread has the time to look at SHOW PROCESSLIST. In this case, the wait
times out because the state looked for has already passed.
Earlier I added some DEBUG_SYNC to prevent this race, but it turns out that
DEBUG_SYNC itself changes the state in the processlist. So when the debug sync
point was hit, the processlist was showing the wrong state, so the wait would
still time out.
Fixed now by looking for the processlist to contain either the "Repair by
sorting" state or the debug sync wait stage.
Also clean up previous attempts to fix it. Set the wait timeout back to
reasonable 60 seconds, and simplify the DEBUG_SYNC operations to work closer
to how the original test case was intended.
The official Debian Wheezy MySQL packages have versions like 5.5.30+dfsg-xxx.
Such version is larger than 5.5.30-yyy, so apt prefers it.
So use instead 5.5.30+maria-yyy, which is larger and can be pulled in
automatically by apt.
Also included are a couple of fixes for test failures in buildbot.
The issue was that there was that SHOW commands could open the table in the store engine, even in cases
where it should not be allowed to do that (ie, the storage engines meta data for that table was under big changes).
The cases where this should not be allowed are:
- ALTER TABLE DISABLE KEYS
- ALTER TABLE ENABLE KEYS
- REPAIR TABLE
- OPTIMIZE TABLE
- DROP TABLE
This patch adds a new mode, protected_against_usage(). If this is used then the SHOW command will wait until the table
is accessable. This is implemented by re-using the already exising 'version' flag for TABLE_SHARE.
It also added functions to be used to change TABLE_SHARE->version instead of changing it directly.
mysql-test/r/myisam-metadata.result:
Added test case
mysql-test/t/myisam-metadata.test:
Added test case
sql/mysqld.cc:
Start from refresh_version 2 as 0 and 1 are reserved.
sql/sql_admin.cc:
Added MYSQL_OPEN_FOR_REPAIR
Updated call to wait_while_table_is_used()
sql/sql_base.cc:
Updated call to wait_while_table_is_used()
- Allow one to specify how the table should be removed (for all commands except show or for all commands).
- Don't allow one to reopen the table if one has called share->protect_against_usage()
sql/sql_base.h:
Added TDC_RT_REMOVE_NOT_OWN_AND_MARK_NOT_USABLE, which is used to mark that no one can reopen this table, except with MYSQL_OPEN_FOR_REPAIR .
- Added MYSQL_OPEN_FOR_REPAIR
- Updated prototype for wait_while_table_is_used()
sql/sql_table.cc:
Updated call to wait_while_table_is_used()
Use MYSQL_OPEN_FOR_REPAIR for open tables that where repaired.
sql/sql_truncate.cc:
Updated call to wait_while_table_is_used()
sql/table.cc:
Use set_refresh_version()
sql/table.h:
Added functions to be used to change TABLE_SHARE->version instead of changing it directly
