<html>
<head>
<meta content="text/html; charset=windows-1252"
http-equiv="Content-Type">
</head>
<body bgcolor="#FFFFFF" text="#000000">
<br>
<br>
<div class="moz-cite-prefix">On 6/11/15 9:32 PM, Eugene Nikanorov
wrote:<br>
</div>
<blockquote
cite="mid:CAJfiwOTmAp4ohZ57o_F=pWJbEvHVmr4AYOS2QoVcUKSd8fgevw@mail.gmail.com"
type="cite">
<div dir="ltr">Hi neutrons,
<div><br>
</div>
<div>I'd like to draw your attention to an issue discovered by
rally gate job:</div>
<div><a moz-do-not-send="true"
href="http://logs.openstack.org/96/190796/4/check/gate-rally-dsvm-neutron-rally/7a18e43/logs/screen-q-svc.txt.gz?level=TRACE">http://logs.openstack.org/96/190796/4/check/gate-rally-dsvm-neutron-rally/7a18e43/logs/screen-q-svc.txt.gz?level=TRACE</a><br>
</div>
<div><br>
</div>
<div>I don't have bandwidth to take a deep look at it, but first
impression is that it is some issue with nested transaction
support either on sqlalchemy or pymysql side.</div>
<div>Also, besides errors with nested transactions, there are a
lot of Lock wait timeouts.</div>
<div><br>
</div>
<div>I think it makes sense to start with reverting the patch
that moves to pymysql.</div>
</div>
</blockquote>
My immediate reaction is that this is perhaps a concurrency-related
issue; because PyMySQL is pure python and allows for full blown
eventlet monkeypatching, I wonder if somehow the same PyMySQL
connection is being used in multiple contexts. E.g. one greenlet
starts up a savepoint, using identifier "_3" which is based on a
counter that is local to the SQLAlchemy Connection, but then another
greenlet shares that PyMySQL connection somehow with another
SQLAlchemy Connection that uses the same identifier.<br>
<br>
I'm not saying this is a bug in PyMySQL or Eventlet necessarily, it
could be a bug in Neutron itself, since none of this code has ever
been used with a true context-switching greenlet environment at the
database connection level.<br>
<br>
<br>
<br>
<br>
<br>
<blockquote
cite="mid:CAJfiwOTmAp4ohZ57o_F=pWJbEvHVmr4AYOS2QoVcUKSd8fgevw@mail.gmail.com"
type="cite">
<div dir="ltr">
<div><br>
</div>
<div>Thanks,</div>
<div>Eugene.</div>
<div><br>
</div>
</div>
<br>
<fieldset class="mimeAttachmentHeader"></fieldset>
<br>
<pre wrap="">__________________________________________________________________________
OpenStack Development Mailing List (not for usage questions)
Unsubscribe: <a class="moz-txt-link-abbreviated" href="mailto:OpenStack-dev-request@lists.openstack.org?subject:unsubscribe">OpenStack-dev-request@lists.openstack.org?subject:unsubscribe</a>
<a class="moz-txt-link-freetext" href="http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev">http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev</a>
</pre>
</blockquote>
<br>
</body>
</html>