I succeeded to reproduce the problem you met. I think it is MySQL’s bug. I have posted the bug report.

http://bugs.mysql.com/bug.php?id=40760

1 queries inside InnoDB, 0 queries in queue
1 read views open inside InnoDB

Sometimes when you check it online the number of “queries inside innodb” will stuck on 1 or something because MySQL will simply stop counting the queries entering/exiting the queue.

Thanks for the response. I changed the value online. When you say counting transactions, do you mean queries like the one below? This is one of the main queries that I saw that was stuck:

SELECT @rank:=@rank-1 AS rank, a.user_id, a.card_id, b.user_name, b.image_url FROM game_winners a
INNER JOIN users b ON a.user_id = b.user_id WHERE a.game_id = 5 ORDER BY a.win_time DESC LIMIT 16;

Did you restart with zero innodb_thread_concurrency or did you change it online ?
I’ve seen minor glitches sometimes (even in stick release) changing it online, though I thougth these were only related to counting transactions.

About patch name – it is part of Innodb IO Patches:
innodb_io_patches.patch

I had a question about changing innodb_thread_concurrency. I changed it on a server yesterday from 8 to 0 and it caused the server to lockup. I am running the hi-perf 5.0.67 release, and I have some tables that use BEFORE INSERT triggers to update another value in a different table. I was curious if you might have any idea why this would happen. Here are a couple outputs from my log file when I made the change:

081113 16:41:32 InnoDB: Error: Freeing a trx which is declared to be processing
InnoDB: inside InnoDB.
TRANSACTION 1 2897690526, not started, process no 17811, OS thread id 1197627712, thread declared inside InnoDB 499
MySQL thread id 243641148, query id 2415637111 XX.XX.XX.XX MY_USERNAME

081113 16:41:32 InnoDB: Error: Freeing a trx which is declared to be processing
InnoDB: inside InnoDB.
TRANSACTION 1 2897690560, not started, process no 17811, OS thread id 1196562752, thread declared inside InnoDB 500
MySQL thread id 243641179, query id 2415637163 XX.XX.XX.XX MY_USERNAME

I had 7 of these show up in my logs, and then I had a couple hundred statements show up in processlist that wouldn’t finish.

thanks – indeed quite an interesting case and makes feel good knowing we have the patch for it Also, I didn’t know innodb_thread_concurrency can be changed online – this is useful to experiment with.