…mysql-deadlocks plugin can help you detect such problems, in conjunction with Percona Toolkit’s pt-deadlock…is too small. The server is approaching max_connections. Overflowing the max_connections setting is a bit like a lack of disk space: it is…
Post: Helgrinding MySQL with InnoDB for Synchronisation Errors, Fun and Profit
November 24, 2011 By 2 Comments
…mysql-test-run.pl to accept a new option: –helgrind. The patch is a copy-paste-modify of the already existing Callgrind support and is…a potential deadlock. The locks in question are LOCK_global_system_variables and LOCK_system_variables_hash. Deadlock is… is remains a lot of the last kind). What…
Post: A quest for the full InnoDB status
October 31, 2008 By 4 Comments
… is that its output is limited to 64000 bytes, so a long list of transactions or a large deadlock dump may easily exhaust the limit. MySQL… output into innodb_status.
Post: Test Drive of Solid
September 22, 2006 By 5 Comments
…it is hard to tell what is really happening. Test 3: Phantom rows: Table before test: select * from test2; +—-+——–+ | id | names | +—-+——–+ | 1 | Mysql | | 2…lock wait not a deadlock. Test 2: SELECT FOR UPDATE: mysql> begin; Query OK, 0 rows affected (0.00 sec) mysql> select * from …
Post: SHOW INNODB STATUS walk through
July 17, 2006 By 40 Comments
…a ;; *** WE ROLL BACK TRANSACTION (2) For last deadlock Innodb shows transactions which caused deadlocks, their state during deadlock, what locks they were holding and what… is done by adjusting innodb_thread_sleep_delay variable. Value is specified in microseconds. mysql tables in use 1, locked 0 is…
Post: SELECT LOCK IN SHARE MODE and FOR UPDATE
August 6, 2006 By 51 Comments
…affects your application and perform changes required. What is missing in Innodb locking.? In my …before MySQL performs like matching, and row is not unlocked if it does not match. Smarter deadlock…FROM INNODBTable; – A lot of shared locks on Innodb table but no updates. Supporting MySQL hints “HIGH_…
Post: READ-COMMITED vs REPETABLE-READ in tpcc-like load
February 11, 2010 By 6 Comments
…what is better isolation level is poping up again and again. Recently it was …is interesting as I expect a lot of contention on row level having small dataset. I used as usually tpcc-mysql… However, however. For 10w run I got 60 Deadlock errors “1213, Deadlock found when trying to get lock; try …
Comment: How Percona diagnoses MySQL server stalls
March 9, 2011 By 6 Comments
…a very interesting story about MySQL deadlocks. I will share here only the results of a long long investigation. The …than with all 16 cores. IMPORTANT: note that what resulted the best combination for cores was to…. if you use cores on different cpus it is BAD, context swiches are much higher. Also …
Comment: Beware of MyISAM Key Cache mutex contention
January 12, 2010 By 10 Comments
…looked a classic old style deadlock. Actually reserches revealed that FreeBSD is …is used for fulltext search, so no InnoDB possible for now. My question is, is it possible that it is only related to a MySQL…a software to put on its knees a monster 16 Xeon cores 16gb box. What is your opinion? What…
Post: MySQL Limitations Part 1: Single-Threaded Replication
October 20, 2010 By 16 Comments
…-to-write ratio is. What are some workarounds? Here are a few I’ve seen: Use DRBD replication instead of MySQL replication. Problem: you… in the same order. If any error occurred, such as a deadlock or lock wait timeout, then the coordinator would instruct the… work well in some cases, such as when deadlocks are common; but it is overall the least disruptive or different from the…
