# MySQL failed to handshake due to LOCK\_thread\_cache not released **URL:** \ **Category:** Percona Server for MySQL 5.7\ **Created:** [April 14, 2019, 6:50pm UTC](https://forums.percona.com/t/mysql-failed-to-handshake-due-to-lock-thread-cache-not-released/6965 "2019-04-14T18:50:02Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![windy.jian](https://avatars.discourse-cdn.com/v4/letter/w/e99b99/32.png) [@windy.jian](https://forums.percona.com/u/windy.jian)\ **Post date:** [April 14, 2019, 6:50pm UTC](https://forums.percona.com/t/mysql-failed-to-handshake-due-to-lock-thread-cache-not-released/6965/1 "2019-04-14T18:50:02Z")
I’m not sure whether it’s ok or not, if I post my help wanted here. It seems that i encounter a bug-like issue. Percona-server 5.7.24-27 [url][MySQL failed to handshake due to LOCK\_thread\_cache not released? - Database Administrators Stack Exchange](https://dba.stackexchange.com/questions/234769/mysql-failed-to-handshake-due-to-lock-thread-cache-not-released%5B/url%5D) ---
**Author:** ![lorraine.pocklington](https://sea1.discourse-cdn.com/flex019/user_avatar/forums.percona.com/lorraine.pocklington/32/37_2.png) [@lorraine.pocklington](https://forums.percona.com/u/lorraine.pocklington)\ **Post date:** [April 15, 2019, 4:41am UTC](https://forums.percona.com/t/mysql-failed-to-handshake-due-to-lock-thread-cache-not-released/6965/2 "2019-04-15T04:41:31Z")
Just looking at this and will feedback on the best course of action… ---
**Author:** ![windy.jian](https://avatars.discourse-cdn.com/v4/letter/w/e99b99/32.png) [@windy.jian](https://forums.percona.com/u/windy.jian)\ **Post date:** [April 15, 2019, 9:50am UTC](https://forums.percona.com/t/mysql-failed-to-handshake-due-to-lock-thread-cache-not-released/6965/3 "2019-04-15T09:50:29Z")
Most people only focus on " too many connections", and lose attentions to other important things. I really don’t know how to emphasize the key things which make them believe it’s abnormal issue other than “too many connections”. ---
**Author:** ![lorraine.pocklington](https://sea1.discourse-cdn.com/flex019/user_avatar/forums.percona.com/lorraine.pocklington/32/37_2.png) [@lorraine.pocklington](https://forums.percona.com/u/lorraine.pocklington)\ **Post date:** [April 15, 2019, 10:52am UTC](https://forums.percona.com/t/mysql-failed-to-handshake-due-to-lock-thread-cache-not-released/6965/4 "2019-04-15T10:52:21Z")
This is most likely to be to do with known issues, good news is that it is likely to have been fixed in 5.7.25-28 which has been released. Here is a release document: [url][https://dev.mysql.com/doc/relnotes/mysql/5.7/en/news-5-7-25.html[/url]](https://dev.mysql.com/doc/relnotes/mysql/5.7/en/news-5-7-25.html%5B/url%5D) The two related bugs are [url][MySQL Bugs: #91941: Deadlock during purge\_logs\_before\_date](https://bugs.mysql.com/bug.php?id=91941%5B/url%5D) and [url][MySQL Bugs: #92108: Deadlock by concurrent show binlogs, pfs session\_variables table & binlog purge](https://bugs.mysql.com/bug.php?id=92108%5B/url%5D) If you are able to provide sample output from running this [url][https://www.percona.com/doc/percona-toolkit/LATEST/pt-pmp.html[/url]](https://www.percona.com/doc/percona-toolkit/LATEST/pt-pmp.html%5B/url%5D) I can maybe get someone in the team to confirm this ---
**Author:** ![windy.jian](https://avatars.discourse-cdn.com/v4/letter/w/e99b99/32.png) [@windy.jian](https://forums.percona.com/u/windy.jian)\ **Post date:** [April 17, 2019, 12:04am UTC](https://forums.percona.com/t/mysql-failed-to-handshake-due-to-lock-thread-cache-not-released/6965/5 "2019-04-17T00:04:00Z")
It’s wonderful, thanks for your answer. I don’t know describe the issue, so i failed to search the bug in the release notes. pt-pmp is a wonderfull tool. Many thanks. ---
**Author:** ![lorraine.pocklington](https://sea1.discourse-cdn.com/flex019/user_avatar/forums.percona.com/lorraine.pocklington/32/37_2.png) [@lorraine.pocklington](https://forums.percona.com/u/lorraine.pocklington)\ **Post date:** [April 17, 2019, 4:17am UTC](https://forums.percona.com/t/mysql-failed-to-handshake-due-to-lock-thread-cache-not-released/6965/6 "2019-04-17T04:17:39Z")
You’re very welcome… totally understand that’s it’s not always easy to get the right search terms BUT we are always here to help. Feel free to use the Forum anytime… finding you on Stack Overflow can be a bit hit and miss though in fact I did see your question there and will go and answer it now 🙂 Thanks for the feedback 🙂