Differential D14875
Fix a possible deadlock in unit tests after an error Authored by epriestley on Dec 24 2015, 2:43 PM. Tags None Referenced Files
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Details
After certain types of errors, we may deadlock when trying to destroy test databases. Specifically, we still have connections open to, say, phabricator_unittest_abasonaknlbaklnasb_herald (or whatever) and MySQL sometimes (not sure exactly when?) waits for them before destorying the database.
Diff Detail
Event TimelineComment Actions Here's a production example of exactly what this looks like: mysql> show full processlist; +-------+------+-----------+-------------------------------------------------------+---------+------+---------------------------------+---------------------------------------------------------------------------------+ | Id | User | Host | db | Command | Time | State | Info | +-------+------+-----------+-------------------------------------------------------+---------+------+---------------------------------+---------------------------------------------------------------------------------+ | 33384 | root | localhost | phabricator_unittest_zsjm7ota2gj4rxpmp3cg7cvo_metamta | Sleep | 5303 | | NULL | | 33385 | root | localhost | phabricator_unittest_zsjm7ota2gj4rxpmp3cg7cvo_user | Sleep | 5303 | | NULL | | 33386 | root | localhost | phabricator_unittest_zsjm7ota2gj4rxpmp3cg7cvo_worker | Sleep | 5303 | | NULL | | 33388 | root | localhost | NULL | Sleep | 5303 | | NULL | | 33389 | root | localhost | NULL | Query | 5303 | Waiting for table metadata lock | DROP DATABASE IF EXISTS `phabricator_unittest_zsjm7ota2gj4rxpmp3cg7cvo_metamta` | | 33527 | root | localhost | phabricator_unittest_7wzk2ezno57z5ufzibk5deqh_metamta | Sleep | 3307 | | NULL | | 33528 | root | localhost | phabricator_unittest_7wzk2ezno57z5ufzibk5deqh_user | Sleep | 3307 | | NULL | | 33529 | root | localhost | phabricator_unittest_7wzk2ezno57z5ufzibk5deqh_worker | Sleep | 3307 | | NULL | | 33531 | root | localhost | NULL | Sleep | 3307 | | NULL | | 33532 | root | localhost | NULL | Query | 3307 | Waiting for table metadata lock | DROP DATABASE IF EXISTS `phabricator_unittest_7wzk2ezno57z5ufzibk5deqh_metamta` | | 34221 | root | localhost | NULL | Query | 0 | NULL | show full processlist | +-------+------+-----------+-------------------------------------------------------+---------+------+---------------------------------+---------------------------------------------------------------------------------+ 11 rows in set (0.00 sec) |