Just to be clear: when you hit max connections, new connections to memcached can/will lag until connections are accepted again. Existing connections won't be slow.
On Wed, 2 Dec 2009, head wrote: > ok guys, so I am still having this problem > > we are using php client with persistent connections (this is pooled > connections in other words) using $memcache_obj->pconnect, which means > that each php thread has it's own connection to memcached > there are 20 http servers, each with minimum 20 php threads, so this > is total of 4000 clients (and that is minimum) > > however from about 3700 clients we are seeing performance decrease, > the answer from memcached for a select can be up to 1 second, this is > much, am I right? > > the memcached server from my calculations is getting about 5000 > requests per second, is this a lot? this is high performance machine, > there is absolutely no swapping *and never was*!!! the load average is > 0.17!! > > Maybe I just need to install more memcached servers? but this one > seems ot be doing nothing anyway > > below are the stats and stats settings, the problem is visible right > now > > > stats settings > STAT maxbytes 3221225472 > STAT maxconns 10000 > STAT tcpport 11211 > STAT udpport 11211 > STAT inter NULL > STAT verbosity 1 > STAT oldest 0 > STAT evictions on > STAT domain_socket NULL > STAT umask 700 > STAT growth_factor 1.25 > STAT chunk_size 48 > STAT num_threads 3 > STAT stat_key_prefix : > STAT detail_enabled no > STAT reqs_per_event 20 > STAT cas_enabled yes > STAT tcp_backlog 1024 > STAT binding_protocol auto-negotiate > END > > stats > STAT pid 2709 > STAT uptime 1727263 > STAT time 1259772057 > STAT version 1.4.1 > STAT pointer_size 64 > STAT rusage_user 29672.975022 > STAT rusage_system 51701.090239 > STAT curr_connections 3188 > STAT total_connections 20452452 > STAT connection_structures 3623 > STAT cmd_get 5977832958 > STAT cmd_set 665620469 > STAT cmd_flush 0 > STAT get_hits 5355401281 > STAT get_misses 622431677 > STAT delete_misses 0 > STAT delete_hits 0 > STAT incr_misses 0 > STAT incr_hits 24302362 > STAT decr_misses 0 > STAT decr_hits 0 > STAT cas_misses 0 > STAT cas_hits 0 > STAT cas_badval 0 > STAT bytes_read 403401321019 > STAT bytes_written 971168343526 > STAT limit_maxbytes 7516192768 > STAT accepting_conns 1 > STAT listen_disabled_num 8554 > STAT threads 3 > STAT conn_yields 0 > STAT bytes 198980367 > STAT curr_items 1077436 > STAT total_items 665620605 > STAT evictions 0 > END >
