Bug #68668 MySQL server freezes
Submitted: 14 Mar 2013 7:35 Modified: 20 Mar 2013 10:30
Reporter: jjj h Email Updates:
Status: Not a Bug Impact on me:
None 
Category:MySQL Server Severity:S2 (Serious)
Version:5.5.30 OS:Linux
Assigned to: CPU Architecture:Any
Tags: server crash too many connections semaphores

[14 Mar 2013 7:35] jjj h 
Description:
Suddenly, it wasn't possible to connect to MySQL because of 'Too many connections'. I had to hard kill it. Attaching log.

How to repeat:
Why it this required? I really don't know how to repeat it.
[14 Mar 2013 7:36] jjj h 
syslog messages

Attachment: mysql.log (application/octet-stream, text), 359.85 KiB.
[19 Mar 2013 20:15] Sveta Smirnova 
Thank you for the report.

MySQL allocates memory buffers for each connection, so, if you have too many, for example, in case of DoS attack, it will simply could not allocate enough memory anymore.

So this case looks like too high max_connections variable value and not a bug.
[20 Mar 2013 10:30] jjj h 
Heh?? Are you serious?? Did you read that syslog messages? It wasn't a memory problem, there were about 10 GB of free memory! Now i'm starting to really consider using a MariaDB cos also support for MySQL starting to suck. Thank you for even not bodhering to read info about this bug.
[20 Mar 2013 19:34] Sveta Smirnova 
Thank you for the feedback.

Well, in the log I see InnoDB monitor output only. So it lists only memory allocated to InnoDB buffer pool and does not least whole server memory usage. You also can have experience lack of file descriptors. Anyway, this looks very much like what I wrote in previous comment and not a bug. To prove this is a bug in MySQL code we need repeatable test case.