We have an apache webserver in front of Tomcat hosted on EC2, instance type is extra large with 34GB memory.
Our application deals with lot of external webservices and we have a very lousy external webservice which takes almost 300 seconds to respond to requests during peak hours.
During peak hours the server chokes at just about 300 httpd processes. ps -ef | grep httpd | wc -l =300
I have googled and found numerous suggestions but nothing seems to work.. following are some configuration i have done which are directly taken from online resources.
I have increased the limits of max connection and max clients in both apache and tomcat. here are the configuration details:
//apache
<IfModule prefork.c>
StartServers 100
MinSpareServers 10
MaxSpareServers 10
ServerLimit 50000
MaxClients 50000
MaxRequestsPerChild 2000
</IfModule>
//tomcat
<Connector port="8080" protocol="org.apache.coyote.http11.Http11NioProtocol"
connectionTimeout="600000"
redirectPort="8443"
enableLookups="false" maxThreads="1500"
compressableMimeType="text/html,text/xml,text/plain,text/css,application/x-javascript,text/vnd.wap.wml,text/vnd.wap.wmlscript,application/xhtml+xml,application/xml-dtd,application/xslt+xml"
compression="on"/>
//Sysctl.conf
net.ipv4.tcp_tw_reuse=1
net.ipv4.tcp_tw_recycle=1
fs.file-max = 5049800
vm.min_free_kbytes = 204800
vm.page-cluster = 20
vm.swappiness = 90
net.ipv4.tcp_rfc1337=1
net.ipv4.tcp_max_orphans = 65536
net.ipv4.ip_local_port_range = 5000 65000
net.core.somaxconn = 1024
I have been trying numerous suggestions but in vain.. how to fix this? I'm sure m2xlarge server should serve more requests than 300, probably i might be going wrong with my configuration..
The server chokes only during peak hours and when there are 300 concurrent requests waiting for the [300 second delayed] webservice to respond.
I was just monitoring the tcp connections with netstat
i found around 1000 connections in TIME_WAIT state, no idea what that would mean in terms of performance, i'm sure it must be adding to the problem.
Output of TOP
8902 root 25 0 19.6g 3.0g 12m S 3.3 8.8 13:35.77 java
24907 membase 25 0 753m 634m 2528 S 2.7 1.8 285:18.88 beam.smp
24999 membase 15 0 266m 121m 3160 S 0.7 0.3 51:30.37 memcached
27578 apache 15 0 230m 6300 1536 S 0.7 0.0 0:00.03 httpd
28551 root 15 0 11124 1492 892 R 0.3 0.0 0:00.25 top
Output of free -m
total used free shared buffers cached
35007 8470 26536 0 1 61
8407 26599
15999 15 15984
output of iostat
avg-cpu: %user %nice %system %iowait %steal %idle
26.21 0.00 0.48 0.13 0.02 73.15
Device: tps Blk_read/s Blk_wrtn/s Blk_read Blk_wrtn
sda1 14.36 4.77 329.37 9005402 622367592
sdb 0.00 0.00 0.00 1210 48
Also at peak time there are about 10-15k tcp connections to membase server[local]
SOME ERRORS IN MODJK LOG, I hope this throws some light on the issue..
[Wed Jul 11 14:39:10.853 2012] [8365:46912560456400] [error] ajp_send_request::jk_ajp_common.c (1630): (tom2) connecting to backend failed. Tomcat is probably not started or is listening on the wrong port (errno=110)
[Wed Jul 11 14:39:18.627 2012] [8322:46912560456400] [error] ajp_send_request::jk_ajp_common.c (1630): (tom2) connecting to backend failed. Tomcat is probably not started or is listening on the wrong port (errno=110)
[Wed Jul 11 14:39:21.358 2012] [8351:46912560456400] [error] ajp_get_reply::jk_ajp_common.c (2118): (tom1) Tomcat is down or refused connection. No response has been sent to the client (yet)
[Wed Jul 11 14:39:22.640 2012] [8348:46912560456400] [error] ajp_get_reply::jk_ajp_common.c (2118): (tom1) Tomcat is down or refused connection. No response has been sent to the client (yet)
~
Worker.properties
workers.tomcat_home=/usr/local/tomcat/
worker.list=loadbalancer
worker.tom1.port=8009
worker.tom1.host=localhost
worker.tom1.type=ajp13
worker.tom1.socket_keepalive=True
worker.tom1.connection_pool_timeout=600
worker.tom2.port=8109
worker.tom2.host=localhost
worker.tom2.type=ajp13
worker.tom2.socket_keepalive=True
worker.tom2.connection_pool_timeout=600
worker.loadbalancer.type=lb
worker.loadbalancer.balanced_workers=tom1,tom2
worker.loadbalancer.sticky_session=True
worker.tom1.lbfactor=1
worker.tom1.socket_timeout=600
worker.tom2.lbfactor=1
worker.tom2.socket_timeout=600
//Solved
thansk all for your valuable suggestions.. i missed out the maxThreads settings for the AJP 1.3 connector.. Now everything seems under control.
I would also start looking at even based servers like nginx.