hello graham,
i am using mod_wsgi embedded mode. not sure how to check out mpm,
prefork or worker since i haven't compiled apache myself.. any clues
on how to find out?
On 24 Ott, 00:16, "Graham Dumpleton" <[EMAIL PROTECTED]>
wrote:
> Because of how mod_wsgi currently works, threading.local() stuff will
> only work in main interpreter. Ie.,
>
> WSGIApplicationGroup %{GLOBAL}
>
> In sub interpreters, the threading.local() object will be destroyed at
> end of request.
>
> To help provide any feedback on everything else, need to know how
> Apache is configured.
>
> That is, are you using mod_wsgi embedded mode or daemon mode. If
> embedded mode, which Apache MPM, prefork (single threaded) or worker
> (multithreaded).
>
> Similarly, for daemon mode, how many processes and threads configured
> for WSGIDaemonProcess.
>
> As I don't have the database experience, hopefully others have tread
> this path can comment as well.
>
> Graham
>
> 2008/10/24 roberto <[EMAIL PROTECTED]>:
>
>
>
> > dear all,
>
> > i'm currently having a hard time in trying to optimize database
> > operations called from an apache/mod_wsgi script. i am using
> > postgresql.
>
> > to give you some background: i have first performed some load testings
> > without database operations, and basically my application starts to
> > experience performance issues at around 650 simultaneous connections,
> > but before that, no errors are reported and everything works fine.
>
> > i have then added database operations using a single persistant
> > connection, i.e. declared global at module level, and at this point
> > after 75 simultaneous connections apache would report a '500 internal
> > server' or an unidentified '0' error.
>
> > in the apache log i see that the errors raised are:
>
> > OperationalError: internal error in 'SELECT * FROM entries...
> > AttributeError: 'NoneType' object has no attribute 'dictresult'
> > ValueError on return self.db.query(qstr)
>
> > which basically mean that either the db connection generated internal
> > errors, or it had not been created [NoneType], or the query returned a
> > value error response from the postgresql server.
>
> > let me clarify immediately that these database operations are not
> > heavy ones: i'm talking about a single basic SQL INSERT statement.
>
> > the steps i have taken:
>
> > 1. tried psycopg2/pygresql
> > results do not differ.
>
> > 2. tried pygresql with dbutils
> > results do not differ.
>
> > 3. used threading.local() to store a new connection when necessary
> > there were improvements, 120 maximum simultaneous connections handled
> > correctly.
>
> > 4. like 3. but added forcing the creation of a connection before every
> > db operation
> > significant improvements, i am currenlty having 5 errors over 400
> > simultaneous connections.
>
> > basically my code now looks something like this:
>
> > ###### local threading
> > LT = threading.local()
>
> > ###### request handler
> > class RequestHandler():
> > def __init__(self):
> > self.SQLconn = None
> > def try_db(self):
> > try:
> > self.SQLconn = LT.SQLconn
> > except:
> > self.SQLconn = LT.SQLconn = DB(dbname=DB_NAME,
> > host=DB_HOST,
> > port=int(DB_PORT), user=DB_USER, passwd=DB_PASS)
> > def handle(self):
> > # force creation of a db connection
> > self.try_db()
> > self.SQLconn.query("INSERT INTO entries (value) VALUES
> > (10);" )
>
> > # create object
> > r = RequestHandler()
>
> > ###### application
> > def application(environ, start_response):
> > output = r.handle()
> > response_headers = [('Content-type', 'text/plain'),
> > ('Content-Length', str(len(output)))]
> > start_response('200 OK', response_headers)
> > return [output]
>
> > i'm sure i'm missing out something, or doing something wrong. anyone
> > would lend a kind hand to me to get out of this? i can scarcely
> > believe that forcing connections all the time is a 'clean' way to go.
>
> > thank you in advance,
>
> > r.
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