Multithreaded status (Was: Re: best way to upgrade)
sgrimm at facebook.com
Thu Apr 12 00:03:16 UTC 2007
Don MacAskill wrote:
> Sorry to thread hi-jack, but I'd love to hear the status of the
> multithreaded version and whether it's in heavy production use at
> Facebook. And, if so, how it's doing, of course. :)
We have been running it exclusively on all our production servers for
several months (though without the changes that have landed in that
branch in the last couple weeks). We found one minor bug in late
February, but aside from that it has been trouble-free for us.
It gets extremely heavy usage; during peak times some instances handle
over 60,000 requests per second sustained, about 95% of which are "get"
requests. We haven't hit a bottleneck yet, but at the moment it appears
that the limiting factor will be the Linux kernel's interrupt handling.
It appears to handle all the interrupts from incoming packets on one
CPU, as we can see the system CPU time on one of the four CPUs exceed
50% while the other three are more in the 20% range. If anyone knows how
to spread that load around, I'd be interested in that (admittedly I
haven't actually gone out and tried to research it yet; for all I know
it's simple to do.)
More information about the memcached