We currently use memcached to share cached objects across wikis, most importantly, entity objects (like data items). Ori suggested we should look into alternatives. This is what he wrote: [21:15] <ori> I was wondering if you think the way you use memcached is optimal (this sounds like a loaded question but I mean it sincerely). And if not, I was going to propose that you identify an optimal distributed object store, and I was also going to offer to help push for procurement and deployment of such a service on the WMF cluster. [21:17] <ori> memcached is a bit of a black box. it is very difficult to get comprehensible metrics about how much space and bandwidth you're utilizing, especially when your data is mixed up with everything else that goes into memcached [21:18] <ori> and the fact that you're serializing objects using php serialize() rather than simple values makes it even harder, because it means that you can only really poke around from php with wikidata code available

Just food for thought, for now... any suggestions for a shared object store?

outer-most uses a HashBagOStuff to implement in-process caching, the second level uses memcached.

On Thu, Oct 2, 2014 at 12:45 AM, Ori Livneh &lt;ori(a)wikimedia.org <mailto:ori@wikimedia.org>> wrote: On Wed, Oct 1, 2014 at 2:46 PM, Daniel Kinzler &lt;daniel.kinzler(a)wikimedia.de <mailto:daniel.kinzler@wikimedia.de>> wrote: We currently use memcached to share cached objects across wikis, most importantly, entity objects (like data items). Ori suggested we should look into alternatives. This is what he wrote: [21:15] <ori> I was wondering if you think the way you use memcached is optimal (this sounds like a loaded question but I mean it sincerely). And if not, I was going to propose that you identify an optimal distributed object store, and I was also going to offer to help push for procurement and deployment of such a service on the WMF cluster. [21:17] <ori> memcached is a bit of a black box. it is very difficult to get comprehensible metrics about how much space and bandwidth you're utilizing, especially when your data is mixed up with everything else that goes into memcached [21:18] <ori> and the fact that you're serializing objects using php serialize() rather than simple values makes it even harder, because it means that you can only really poke around from php with wikidata code available The other major problem with memcache is that it doesn't support complex data structures like lists, queues, sets, or maps, so when you want to do things like, say, push or pop an item from a queue, you end up having to retrieve the entire collection, unserialize it, manipulate it locally, re-serialize it, and transmit it back in its entirety. Use more Redis maybe?