even so, 50 seconds spent on a single-row update (that has a PK involved
cause the update is somewhat
update session_table
set locked = False,
client_ip=blablabla,
modified_datetime=now,
session_data=blablablabla,
unique_key=blablabla
where id = number
)
is a ginormous amount of time . Any network hiccups between the app server
and the mysql instance ?
On Tuesday, April 16, 2013 11:20:36 PM UTC+2, Niphlod wrote:
>
> if you're storing sessions in the database an update is made for every
> request that changes the session ..... can you confirm that this would be
> the case (i.e. your app does a lot of session.whatever changes) ?
>
> On Tuesday, April 16, 2013 11:09:50 PM UTC+2, Yarin wrote:
>>
>> We've had our production application running problem free for 10 months,
>> but in the past month or so we've started encountering "MySQL server has
>> gone away" errors sporadically, but with increasing frequency. Currently it
>> is happening every few days, sometimes several times a day. This has never
>> happened to the app in test or development environments.
>>
>> These factors lead me to believe this problem is manifesting itself as a
>> result of increased activity. Still, our loads are relatively low. We may
>> have a handful of users connected at any one time, but not more than 10.
>>
>> Looking at our Newrelic database reports, we're seeing that the a huge
>> spike in db clock time always coincides with the errors, and the culprit is
>> always the *web2py_session_* UPDATE call. (It may possibly correlated
>> with new user signups, but we haven't been able to confirm this)
>>
>> Stranger still, in one of these incidents there were over a hundred calls
>> made to web2py_session_{app} UPDATE, many times the number of total
>> requests made to the app over the same period.
>>
>> Traces:
>>
>> Traceback (most recent call last):
>> File "/opt/web-apps/web2py/gluon/main.py", line 624, in wsgibase
>> BaseAdapter.close_all_instances('rollback')
>> File "/opt/web-apps/web2py/gluon/dal.py", line 529, in close_all_instances
>> db._adapter.close(action)
>> File "/opt/web-apps/web2py/gluon/dal.py", line 509, in close
>> getattr(self, action)()
>> File "/opt/web-apps/web2py/gluon/dal.py", line 1655, in rollback
>> if self.connection: return self.connection.rollback()
>> File
>> "/usr/lib/python2.6/site-packages/newrelic-1.12.0.9/newrelic/hooks/database_dbapi2.py",
>> line 76, in rollback
>> return self._nr_connection.rollback()
>> OperationalError: (2006, 'MySQL server has gone away')
>>
>>
>> and
>>
>> Traceback (most recent call last):
>> File "/opt/web-apps/web2py/gluon/main.py", line 551, in wsgibase
>> session._try_store_in_db(request, response)
>> File "/opt/web-apps/web2py/gluon/globals.py", line 726, in _try_store_in_db
>> table._db(table.id == record_id).update(**dd)
>> File "/opt/web-apps/web2py/gluon/dal.py", line 8812, in update
>> ret = db._adapter.update(tablename,self.query,fields)
>> File "/opt/web-apps/web2py/gluon/dal.py", line 1372, in update
>> self.execute(sql)
>> File "/opt/web-apps/web2py/gluon/dal.py", line 1694, in execute
>> return self.log_execute(*a, **b)
>> File "/opt/web-apps/web2py/gluon/dal.py", line 1688, in log_execute
>> ret = self.cursor.execute(*a, **b)
>> File
>> "/usr/lib/python2.6/site-packages/newrelic-1.12.0.9/newrelic/hooks/database_dbapi2.py",
>> line 36, in execute
>> return self._nr_cursor.execute(sql, *args, **kwargs)
>> File "/usr/lib64/python2.6/site-packages/MySQLdb/cursors.py", line 173, in
>> execute
>> self.errorhandler(self, exc, value)
>> File "/usr/lib64/python2.6/site-packages/MySQLdb/connections.py", line 36,
>> in defaulterrorhandler
>> raise errorclass, errorvalue
>> OperationalError: (1205, 'Lock wait timeout exceeded; try restarting
>> transaction')
>>
>>
>>
>> What could be the cause of all this? Any ideas welcome.
>>
>>
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