Wow I never tought synfony could do such thing. Are you using the last stable release?
Regards On 11/23/09, Chris F <[email protected]> wrote: > All, > > We've narrowed the issue down to symfony's session handling. > > It stores all sessions in a key called "_metadata" > Every new session would have it's data appended to the value. > > This value would grow to upwards of 15000 entries and over 1MB in > size. > > At a set time garbage collection would clean up the metadata entry and > subsequently our latency and network throughput the drop to the floor. > > Due to consistent hashing every request from our dynamic servers would > retrieve that key/value pair from mem1 eventually saturate the NIC. > > Our developers are working to remove the dependency on _metadata. > > Thanks > > Chris > > > On Nov 21, 4:43 pm, Chris F <[email protected]> wrote: >> I have a small memcached server pool of 3 instances(m1.small) and an >> autoscaling cloud of linux instances(4-20 c1.xlarge AWS EC2) that >> store sessions to them using the memcache PECL extension wrapped by >> Symfony 1.2 framework. >> >> In the past week we've had an increase in traffic which has resulted >> in a recurring latency issue caused by memcache. >> >> We see the network throughput of our web servers slowly creep up over >> an hour then drop suddenly. >> Please see the links below to the zabbix graph pics. >> >> As the network throughput rises on both web and memcache servers the >> latency rises. >> The web traffic does not correlate directly with the dropoffs in >> network throughput that can be seen on the web servers. Analyzing the >> traffic using ntop showed 98% of the traffix was from memcache. >> >> It seems that the pecl memcache extension is not properly hashing the >> keys evenly across the 3 memcache servers. In fact I had added mem3 >> to alleviate the load with no significant gain. >> Also the amount of memcache traffic seems highly suspect. >> >> Can someone assist in diagnosing this issue? >> See below for additional info and links. >> >> Thanks >> >> Chris >> >> ELB Latency statistics:http://imgur.com/ZM4mh.png >> Memcache server network utilization:http://imgur.com/Sg8fJ.png >> PHP server network utilization:http://imgur.com/zxzWU.png >> Memcache server CPU load:http://imgur.com/tW8La.png >> PHP server CPU load:http://imgur.com/S5wio.png >> WWW requests per minute:http://imgur.com/242eV.png >> >> pecl memcache settings: >> Active persistent connections 1 >> Version 2.2.5 >> Revision $Revision: 1.111 $ >> >> Directive Local Value Master Value >> memcache.allow_failover 1 1 >> memcache.chunk_size 32768 32768 >> memcache.default_port 11211 11211 >> memcache.default_timeout_ms 1000 1000 >> memcache.hash_function crc32 crc32 >> memcache.hash_strategy consistent consistent >> memcache.max_failover_attempts 20 20 >> >> memcache server setting: >> memcached -d -p 11211 -u nobody -m 1024 -c 2048 -P /var/run/memcached/ >> memcached.pid >> v 1.4.0 > -- Sent from my mobile device Gabriel Sosa Si buscas resultados distintos, no hagas siempre lo mismo. - Einstein
