tomcat-users mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Rainer Jung <rainer.j...@kippdata.de>
Subject Re: Apache/Tomcat - mod_jk can't receive response from Tomcat
Date Tue, 15 Jul 2008 09:04:09 GMT
Bajbutovic, Zoran schrieb:
> We have Apache and Tomcat running on different servers, using mod_jk. 
> From time to time we got the following errors from Tomcat.
> 
> 		[Thu Jul 10 16:43:21 2008]  [jk_ajp_common.c (1250)]:
> Tomcat is down or network problems. No response has been sent to the
> client (yet)
> 		[Thu Jul 10 16:43:21 2008]  [jk_ajp_common.c (1449)]:
> ERROR: Receiving from tomcat failed, recoverable operation. err=0
> 		[Thu Jul 10 16:43:21 2008]  [jk_ajp_common.c (783)]:
> ERROR: can't receive the response message from tomcat, network problems
> or tomcat is down (200.200.1.1
> 		:8009), err=-1
> 		[Thu Jul 10 16:43:21 2008]  [jk_ajp_common.c (1468)]:
> sending request to tomcat failed in send loop. err=0
> 
> We were able to simulate the failure, and found out that Tomcat became
> unresponsive once the number of threads reach 252. We double check all

You mean the number of threads inside Tomcat?
What are those doing? Try to get a thread dump, look at it, and if you 
find it to difficult, provide it to the list.

> our configuration settings but couldn't find anything wrong. Any help
> will be greatly appreciated.

Which version of mod_jk are you using?
Which version of httpd and Tomcat are you using?
Which platform?

Usually the messages would indicate, that your webapp inside Tomcat got 
stuck and ate all the available threads. One can easily check with a 
thread dump.

> Here are our settings:
> 
> AJP connector:
> 
> I suggest setting maxThreads in TOMCAT_HOME/conf/server.xml for AJP
> connector to slightly higher value than Apache's thread limit
> 
> 
> Please see below maxThreads values in  our conf (I don't deleted the
> comments lines) 
> 
>   <Connector protocol="AJP/1.3" port="8009" maxThreads="600"
> minSpareThreads="5" maxSpareThreads="100" acceptCount="500" debug="0"
> connectionTimeout="60000" enableLookups="false"
> disableUploadTimeout="true" useURIValidationHack="false"
> redirectPort="4443" />
> 
> MPM - we use prefork:
> 
> ##
> ## Server-Pool Size Regulation (MPM specific)
> ##
> # prefork MPM
> # StartServers: number of server processes to start
> # MinSpareServers: minimum number of server processes which are kept
> spare
> # MaxSpareServers: maximum number of server processes which are kept
> spare
> # MaxClients: maximum number of server processes allowed to start
> # MaxRequestsPerChild: maximum number of requests a server process
> serves
> 
> <IfModule prefork.c>
> StartServers       8
> MinSpareServers    5
> MaxSpareServers   20
> MaxClients       250
> MaxRequestsPerChild  1000
> </IfModule>
> 
> Worker.properties:
> 
> # list the workers by name
> worker.list=app
> 
> # ------------------------
> # First tomcat server
> # ------------------------
> worker.app.port=8009
> worker.app.host=SERVER_NAME
> worker.app.type=ajp13
> 
> # worker "app" use up to 10 sockets, which will stay no more than 10mn
> in cache
> worker.app.cachesize=10
> 
> # worker "app" ask operating system to send KEEP-ALIVE signal on the
> connection
> worker.app.socket_keepalive=1
> 
> # worker "app" want ajp13 connection to be dropped after 5mn == 300
> (timeout), 10 min == 600
> worker.app.socket_timeout=60
> worker.app.cache_timeout=60
> 
> #This features has been added in jk 1.2.6 to avoid problem with hung
> tomcat's
> worker.app.connect_timeout=60
> 
> #forwarding to it a request. The parameter is the delay in milliseconds
> to wait for the PONG reply.
> #This features has been added in jk 1.2.6 to avoid problem with hung
> tomcat's
> #worker.app.prepost_timeout=60
> #
> # Specifies the load balance factor when used with
> # a load balancing worker.
> # Note:
> #  ----> lbfactor must be > 0
> #  ----> Low lbfactor means less work done by the worker.
> #worker.app.lbfactor=100
> #
> # END workers.properties
> 
> 
> Zoran Bajbutovic 
> Email: zbajbutovic@dynamic.ca


---------------------------------------------------------------------
To start a new topic, e-mail: users@tomcat.apache.org
To unsubscribe, e-mail: users-unsubscribe@tomcat.apache.org
For additional commands, e-mail: users-help@tomcat.apache.org


Mime
View raw message