Keeping objects between requests

[Joel Samuelsson]

I'm using cassandra as a database with web2py and would like to keep the cassandra session between requests to reduce session recreation and lower latencies. Is this a bad idea? And how would I do it?

Any tips appriciated!

[Val K]

You can save any object in the module or current, but if you use more than one worker you will have independent instance of that object per worker

[Joel Samuelsson]

Did this in the top of a controller:

from gluon import current
try:
 if current.ts_db is not None:
   Databases.setTSDB(current.ts_db)
except AttributeError:
 current.ts_db = Databases.setTSDB()

Databases is a model and setTSDB looks liks this:

 @staticmethod
 def setTSDB(db = None):
   if db is None:
     logger.debug("Creating new TS DB")
     db = CassandraConnection([TS_DB_URL], TS_DB_PORT)
   DriverFactory.setDB(db)
 return db

Whenever I make a request I get the "Creating new TS DB" log so the object doesn't seem to be saved. Any ideas why?

I should mention that I'm running web2py behind Apache with mod_wsgi.

[Val K]

Ups, sorry current is thread local and renew per request, use regular mudule

[Joel Samuelsson]

Thanks, this works. Is that how people usually do to keep db connections alive?

[Val K]

Yes, see pydal implementation https://github.com/web2py/pydal/blob/master/pydal/connection.py
It is just 176 lines