Am Freitag 30 Mai 2008 14:01:35 schrieb Audun Ytterdal:
I run trunk in front of a site. I have 3 varnishservers, all with
32GB
of ram serving only small pictures, thumbnails and profile pictures.
The cacheset is pretty large (1.5 TB) and changing much over time.
And before you all ask why I don't just server partitioned data from
several apache/nginx/lighttpd servers It's because we're not there
yet. The varnishes all fetch their content from one lighttpd server .
I run into the Thread pileup-problem
I've set threadlimit to 1500 and it usually lies between 80 and 700.
While restarting it hits the 1500 limit and stays there for a few
minutes. Then it gradualy manages to controll traffic and ends up
around 80 threads. It usually grows a bit. But not over 700-1000 ish.
But suddenly, under high traffic it goes up to the limit beeing 1500
or 4000 or whatever i set it to. Then it stays there and usualy never
recovers without a restart.
I guess it's because the backend at some point answers slowly. But is
there a way to easier get out of this situation.
Running varnish like this:
(redhat 4.6 32 GB RAM)
/usr/sbin/varnishd -a :80 -f /etc/varnish/nettby.vcl -T 127.0.0.1:82
-t 120 -w 2,2000,30 -u varnish -g varnish -p client_http11 on -p
thread_pools 4 -p thread_pool_max 4000 -p listen_depth 4096 -p
lru_interval 3600 -h classic,59 -s
file,/var/varnish/varnish_storage.bin,30G -P /var/run/varnish.pid
and for testing purposes
(redhat 5.1 32 GB RAM)
varnish 22959 17.1 45.2 20187068 14938024 ? Sl May29 160:40
/usr/sbin/varnishd -a :80 -f /etc/varnish/nettby.vcl -T 127.0.0.1:82
-t 120 -u varnish -g varnish -p thread_pools 4 -p thread_pool_max
2000 -p client_http11 on -p listen_depth 4096 -p lru_interval 3600 -h
classic,59 -s malloc,60G -P /var/run/varnish.pid
Each varnish handles about 3000 req/s before it caves in.
Any suggestions?
not really sure if I can help, but at least I can tell you that we run a
similar setup. however, our images are never changed, only get deleted,
and if it happens, a PURGE request clears them off the proxies.
Therefore, we go a little different route: huge file based cache (over
500 GB), and huge default_ttl (one year, only 404 errors have a smaller
ttl of 3 hours). we also have 32 GB installed, and set thread_pool_max
to 8000, and -h classic,259 according to a hint in the wiki.
I did not look at the thread count for a longer time, and don't really
know if 8000 is any good or bad. since everything works nice, I just
keep it as it is.
having said all this, the request pattern is not really like yours. the
cache file is only used by ~60 % after 50 days, and peak traffic for
each out of three proxies is only about 300 req/s. one would probably
cope well with our traffic, we run three as a simple HA measure.
Cheers,
Sascha
Are the parameters sane?
--
Audun
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