Creating this for the record.
labsdb1009 crashed while attempting to do the massive alters for: T166204
InnoDB: ###### Diagnostic info printed to the standard error stream InnoDB: Error: semaphore wait has lasted > 600 seconds InnoDB: We intentionally crash the server, because it appears to be hung. 2017-07-13 22:21:07 7eefc3bfd700 InnoDB: Assertion failure in thread 139568246413056 in file srv0srv.cc line 2418 InnoDB: We intentionally generate a memory trap. InnoDB: Submit a detailed bug report to http://bugs.mysql.com. InnoDB: If you get repeated assertion failures or crashes, even InnoDB: immediately after the mysqld startup, there may be InnoDB: corruption in the InnoDB tablespace. Please refer to InnoDB: http://dev.mysql.com/doc/refman/5.6/en/forcing-innodb-recovery.html InnoDB: about forcing recovery. 170713 22:21:07 [ERROR] mysqld got signal 6 ;
It crashed when alterting templatelinks (61G).
labsdb1011 finished the alters with no issues a couple of days ago, so I have given labsdb1009 another go to see how it goes this time.
Replication didn't get broken or anything upon restart.