On Jun 22, 2009, at 11:31 AM, Alan Runyan wrote: > On Mon, Jun 22, 2009 at 10:06 AM, Andreas Jung<li...@zopyx.com> wrote: >> On 22.06.09 16:56, Pedro Ferreira wrote: >>> Hello all, >>> We occasionally get some messages like this in the logs: >>> >>> 2009-06-22T14:12:42 (30651/137.138.128.213:35787) Transaction >>> blocked >>> waiting for storage. Clients waiting: 1. >>> >>> But today we eventually got to: >>> >>> 2009-06-22T16:00:11 (30651/137.138.4.153:53416) Transaction blocked >>> waiting for storage. Clients waiting: 204. >>> >>> Which lasted some minutes. During that time, our system seemed to >>> hang, >>> even if it was possible to connect to the db through the command >>> line. >>> It eventually went back to normal by itself. >>> Any clue on what might have caused this? >> The reason is likely a long running transaction. Since the storage >> server >> is single-threaded, a long running transaction will block pending >> requests. > > Question: > Will the ZEO server respond to LOAD requests from ZEO clients while > WRITEs are pending?
Yes, however, if the last phase of 2-phase commit takes long enough, clients will become blocked altogether. This is because vote requests get blocked and eventually, all of the client threads are blocked voting. Jim -- Jim Fulton Zope Corporation _______________________________________________ For more information about ZODB, see the ZODB Wiki: http://www.zope.org/Wikis/ZODB/ ZODB-Dev mailing list - ZODB-Dev@zope.org http://mail.zope.org/mailman/listinfo/zodb-dev