Apache mod_proxy, tomcat 5.5 - sometimes no response

Running tomcat 5.5 with (64 bit centos, 8 gb ram), mysql, apache

"-server -Xss1M -Xms2G -Xmx3550m -XX:+UseConcMarkSweepGC -XX:NewSize=1G -XX:MaxPermSize=512m XX:CMSInitiatingOccupancyFraction=70"

running multiple application on tomcat via apache as front end (almost 10 domains for various context paths on tomcat)

apache config:
httpd.conf:

KeepAlive On

ProxyRequests Off

ProxyPreserveHost On

Timeout 1800

ProxyPass         /demo  http : //127.0.0.1:8080/demo

ProxyPassReverse  /demo  http :// 127.0.0.1.22:8080/demo

ProxyPass         /demo2  http :// 127.0.0.1:8080/demo2

ProxyPassReverse  /demo2  http :// 127.0.0.1.22:8080/demo2

SetEnv force-proxy-request-1.0 1

SetEnv proxy-nokeepalive 1

.htaccess

RewriteEngine on

RewriteCond %{HTTP_HOST} ^test\.web\.com$ [开发者_如何学GoNC]

RewriteRule (.*) http : //test.web.com/demo/$1 [L,R=301]

RewriteCond %{HTTP_HOST} ^test2\.web\.com$ [NC]

RewriteRule (.*) http : //test2.web.com/demo2/$1 [L,R=301]

Everything works great, including response time and all 10 instances (various domains), but 3-4 times a day: http://test.web.com does not give any response, it throws blank page (completely blank) while at the time when its blank, direct url: http://127.0.0.1:8080/demo works fine. It means tomcat still works fine, it seems apache is not able to forward the request to tomcat - right now load on per instance is 20 per minute.

Sometime everything works for 3-4 days, then it happens, sometimes it keeps on happening. Blank page comes for some time - and after 3-4 minutes - page starts coming.

Try using JKMount rather than your proxy config?

I have something similar with apache config:

# 
# Mod_jk settings 
# 
JkWorkersFile "conf/workers.properties" 
JkLogFile "logs/mod_jk.log" 
JkLogLevel info

# Select the log format
JkLogStampFormat "[%a %b %d %H:%M:%S %Y] "

# JkOptions indicate to send SSL KEY SIZE, 
JkOptions     +ForwardKeySize +ForwardURICompat -ForwardDirectories

# JkRequestLogFormat set the request format 
JkRequestLogFormat     "%w %V %T"


<VirtualHost 127.0.0.1:8443>
    SSLEngine On
    SSLCertificateFile conf/ssl/domainacom.cert
    SSLCertificateKeyFile conf/ssl/domainacom.key
    ServerAdmin boss@domain.com
    ServerName wwwdomainacom
    ErrorLog logs/wwwdomainacom-error_log
    CustomLog logs/wwwdomainacom-access_log common
    JkMount /* wwwdomainacom
</VirtualHost>

then in conf/workers.properties:

worker.list=domainacom,domainbcom

# Set properties for domainacom (ajp13) 
worker.domainacom.port=8009
worker.domainacom.host=localhost
worker.domainacom.type=ajp13
worker.domainacom.lbfactor=50
worker.domainacom.cachesize=10
worker.domainacom.cache_timeout=600
worker.domainacom.socket_keepalive=1
worker.domainacom.reclycle_timeout=300

# Set properties for domainbcom (ajp13) 
worker.domainbcom.port=8011
worker.domainbcom.host=localhost
worker.domainbcom.type=ajp13
worker.domainbcom.lbfactor=50
worker.domainbcom.cachesize=10
worker.domainbcom.cache_timeout=600
worker.domainbcom.socket_keepalive=1
worker.domainbcom.reclycle_timeout=300

finally in tomcat:

<!-- Define an AJP 1.3 Connector on port 8009 -->
<Connector port="8009" 
           enableLookups="true" redirectPort="8443" protocol="AJP/1.3" URIEncoding="UTF-8" />

as far as i know, i never have any lost requests.

Are you using Load Balancer? Please make sure its not PING based. Sometimes hosting provider rejects pings based network load.