memcached.org/wiki also inside the source tarball there's a "protocol.txt" that explains the raw stats thoroughly. You seem to be referring to the php api's stats call.
On Mon, 17 May 2010, Tim Sneed wrote: > Great thanks for the information! Is there any documentation available from > the project team that explains the monitoring aspects of memcached? Such as > the methods of receiving stats (if there are any aside from getStats())? > > > -----Original Message----- > From: memcached@googlegroups.com [mailto:memcac...@googlegroups.com] On > Behalf Of dormando > Sent: Thursday, May 13, 2010 4:57 PM > To: memcached > Subject: Re: Global Lock When Getting Stats? > > > I was watching a Memcached video spoken by John Adams when I heard > > something that made me curious. When one gets stats from memcached, > > does it really perform a global lock? Does anyone have any good test > > cases on what sort of impact there is with an increasing node size > > with respect to performance degradation? > > 'stats sizes' grabs a global lock and iterates the whole cache. we don't > recommend you run that one. All other stats commands are extremely fast. > > > I am looking to do some research on expanding our product to support > > real-time monitoring, management, and analysis of memcached. But I'm a > > little concerned that this lock occurs during every stat collection, > > so much to the point that John Adams mentions that it can noticeably > > degrade the performance of memcached. I tried to do some research on > > my own but am finding very little performance analysis or any > > benchmark info with respect to constant polling (minimally 30 sec > > interval) of a enterprise-level memcached distributed system. Has > > anyone seen bad performance with respect to a large cluster and > > gathering stats? Any info would be great, thanks! > > There is no major lock every stat collection. There's a minor lock and > reading the values is very fast. > > A while ago twitter was running an extremely old version of memcached and > they took a long time to upgrade. That particular version had a bug in > stats collection that was *missing* a mutex lock, and would thus crash > sometimes. So they were afraid of running stats commands. That bug hasn't > existed for three years at least. > > -Dormando > >
