>> I updated to 3.3.6 and the system doesn't become totally unresponsive >> any more, although SSH latency is still pretty high when the client is >> trying to load a page. The browser still hangs after loading a few >> page elements on some websites (www.google.com/nexus/) but now if I >> let the page load for long enough, it does eventually load, but it can >> take 5 minutes or longer. Restarting squid sometimes makes it load a >> lot faster. It's possible that it hangs more often when loading >> elements from a different domain or subdomain (services.google.com, >> doubleclick.net) but that could be a coincidence. The client's and >> server's internet connections are strong. > > If that were related it might be DNS or TCP congestion (ECT, Window Scaling, > MTU) issues. I set the following on the squid server and client with no noticeable change: echo 0 > /proc/sys/net/ipv4/tcp_ecn echo 1 > /proc/sys/net/ipv4/ip_no_pmtu_disc echo 0 > /proc/sys/net/ipv4/tcp_window_scaling >>> The usual cause of these type of issues is forwarding loops, although >>> your >>> low of socket usage indicates that is probably not the problem. >> >> Yes, I'm the only user. > > It might be related to the 10ms select-loop delays in Squid. If you load the > proxy with a bunch more requests (say 20 in parallel constantly) does it > still happen? I opened 20 tabs in firefox and the 3 tabs which started loading first loaded slightly more content than usual. >> I have this on the squid system while the browser seems to hang so I >> think there is plenty of available physical RAM: >> >> # free >> total used free shared buffers cached >> Mem: 1985944 1638368 347576 0 838340 219332 >> -/+ buffers/cache: 580696 1405248 >> Swap: 1048572 0 1048572 >> >> 2013/07/04 08:51:04.143 kid1| event.cc(250) checkEvents: checkEvents >> 2013/07/04 08:51:04.143 kid1| AsyncCall.cc(18) AsyncCall: The >> AsyncCall MaintainSwapSpace constructed, this=0xbb3310 [call546] >> 2013/07/04 08:51:04.143 kid1| AsyncCall.cc(85) ScheduleCall: >> event.cc(259) will call MaintainSwapSpace() [call546] > > These happening at regular but widely separated intervals? or lots across > the slowdown period? They happen about once per second during the slowdown. > This is the main cache garbage collection operations, so should be checked > and purge some things every so often. If they happen unuslally frequently > during the slow-down period it means the cache is overflowing and CPU is > busy purging contents until enough space is available for the new traffic. squid CPU usage is very low during the slowdown at .5% - 2.5% with most of the CPU idle. I get 18M cache size every time I check: # du -sh /var/cache/squid 18M /var/cache/squid I've tried each of these with no noticeable change: cache_dir ufs /var/cache/squid 100 16 256 cache_dir aufs /var/cache/squid 100 16 256 cache_dir diskd /var/cache/squid 100 16 256 - Grant
