[Zope] zeo cache-size tuning - number of obj. vs MB
tseaver at palladion.com
Wed Jan 6 03:57:45 EST 2010
-----BEGIN PGP SIGNED MESSAGE-----
Gaute Amundsen wrote:
> What's the difference between the to cache-size settings here?
> I've not been able to find a good description to guide me in finding the
> right values.
> <zodb_db main>
> mount-point /
> cache-size 10000 1.
> server foo:9080
> storage main
> name zeostorage
> var $INSTANCE/var
> cache-size 20MB 2.
> As far as I've been able to determine, the second one 2. refers to a
> separate cache at the zeo connection level.
The ZEO client cache is a disk-based cache, separate from the RAM-based
cache used by any ZODB connection. It doesn't use RAM, per se, except
for an in-memory index of OID -> (layer, offset).
> Running 9 zeo clients (2.7.9) like this on a frontend with 4G ram,
> varnish, apache, and haproxy. Tethering on the edge of too much
> swapping. Needing to cut down..
Assuming you are running with the default number of "worker threads"
(4): 10000 objects in the cache * 4 active connections per appserver *
9 appservers means you are caching 360,000 objects in RAM. If they are
putting you into swap, then you are averaging something like 10Kb per
object, which is pretty big.
> Would it be better to spend all the memory on 1?
> Is there a good way to find a balance?
I think I might cut down on the number of appservers on that host, if it
truly is hitting swap. Or trim the number of threads per appserver down
from 4 to 2 or 3.
Tres Seaver +1 540-429-0999 tseaver at palladion.com
Palladion Software "Excellence by Design" http://palladion.com
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.4.9 (GNU/Linux)
Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org
-----END PGP SIGNATURE-----
More information about the Zope