On Thu, Apr 16, 2015 at 01:27:51PM -0400, Jay Pipes wrote: > On 04/16/2015 09:54 AM, Sean Dague wrote: > >On 04/16/2015 05:20 PM, Qiming Teng wrote: > >> > >>Wondering if there is something misconfigured in my devstack > >>environment, which was reinstalled on RHEL7 about 10 days ago. > >>I'm often running into mysql connections problem as shown below: > >> > >>$ mysql > >>ERROR 1040 (HY000): Too many connections > >> > >>When I try dump the mysql connection list, I'm getting the followng > >>result after a 'systemctl restart mariadb.service': > >> > >>$ mysqladmin processlist | grep nova | wc -l > >>125 > >> > >>Most of the connections are at Sleep status: > >> > >>$ mysqladmin processlist | grep nova | grep Sleep | wc -l > >>123 > >> > >>As for the workload, I'm currently only running two VMs in a multi-host > >>devstack environment. > >> > >>So, my questions: > >> > >> - Why do we have so many mysql connections from nova? > >> - Is it possible this is caused some misconfigurations? > >> - 125 connections in such a toy setup is insane, any hints on nailing > >> down the connections to the responsible nova components? > >> > >>Thanks. > >> > >>Regards, > >> Qiming > > > >No, that's about right. It's 1 connection per worker. By default most > >daemons start 1 worker per processor. Each OpenStack service has a bunch > >of daemons. It all adds up pretty quick. > > And just to add to what Sean says above, there's nothing inherently > wrong with sleeping connections to MySQL. What *is* wrong, however, > is that the default max_connections setting in my.cnf is 150. :( I > frequently recommend upping that to 2000 or more on any modern > hardware or decent sized VM. > > Best, > -jay > Thanks, guys. So the key takeaway for me is:
- 100~200 mysql connections is not big problem, provided those connections are sleeping; - Tuning mysql to support larger number of user connections is a must; - Number of mysql connections is not proportional to the number of VMs, it is more related to the number of cores, number of workers etc. Regards, Qiming __________________________________________________________________________ OpenStack Development Mailing List (not for usage questions) Unsubscribe: [email protected]?subject:unsubscribe http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev
