[openstack-dev] [all] DevStack switching from MySQL-python to PyMySQL
Mike Bayer
mbayer at redhat.com
Thu Jun 18 19:47:16 UTC 2015
On 6/18/15 1:28 PM, Matt Riedemann wrote:
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> It's not only neutron, I saw some pymysql failures in nova the other
> day for 'too many connections' or some such related error.
"too many connections" is an error raised by MySQL when more connections
are attempting to connect than the max_connections setting. It defaults
to 100 but it is often set at 1024 in distributions. An Openstack
application that uses oslo.db will go through oslo.db's create_engine()
routine which defaults the max number of connections per python process
to 15, and when the process is idle, this drops to 5.
Which means, there have to be over 60 python processes all hitting the
DB at the max to get that error, if max_connections is at 1024. Or
the connection pool is totally broken (e.g. with eventlet monkeypatching
perhaps), which would be a critical issue for me to fix.
So I'd love to see how the "too many connections" error actually
happens. Please share whatever you have on that.
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