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Ask the Experts : Out of Memory - Out of swap space
asked by sunilatte
This is a regular OutOfMemoryError in the Java Heap, you are receiving the error cause
- You have set -Xmx too low or
- You have a memory leak in your application
The reason the JVM crashes, is cause you are using a very old JVM, I suggest you
- Upgrade your JVM to the latest 1.6.0 release
- Use a 64 bit JVM
- Increase -Xmx
If you are still seeing an OutOfMemoryError after that, you probably have a memory leak. For that you can use a profile to analyze your memory usage. I prefer YourKit
answered by fhanik on August 30, 2012 04:10 PM
Ask the Experts : Tomcat hangs on production and doesn’t respond to new http requests.
We are having issues with tomcat on production. Tomcat hangs on production and doesn’t respond to new http requests.
asked by gaurav
7.0.11 was a very early release and most likely you are running into a bug. I would upgrade to 7.0.27. Even in that release, there are reports of the system hanging -
https://issues.apache.org/bugzilla/show_bug.cgi?id=53173
The bug above shows how a newly introduced feature in Tomcat 7, has had an issue in all released versions.
There are a few work arounds
- Use Tomcat 6 - this release is unaffected by the bug above
- Wait for next release of Tomcat 7
- Increase maxConnections value to delay the symptom of this problem
answered by fhanik on June 4, 2012 03:59 AM
Ask the Experts : Debugging JBoss
I have been running Tomcat 6.0.24 in a Netbeans development environment for months. Yesterday, I started getting a "java.lang.NoClassDefFoundError: org/jboss/logging/Logger" message when I try to start Tomcat in Netbeans services. I'm not running jboss, and to my knowledge, I haven't made any changes to my computer. The server output is:
asked by rhurdle
Most likely you have a jboss jar somewhere in your system.
To troubleshoot this, I recommend enabling the -XX:+TraceClassLoading option, and then scan the output for what library it is trying to load your classes from.
answered by fhanik on June 12, 2012 08:04 AM
Ask the Experts : Disable caching/force reloading of JNDI resources
The idea was to provide multiple web applications running inside a Tomcat instance with configuration properties from config files located outside the WAR file of the applications. I'm currently trying to provide these configuration properties with a global naming resource (defined inside the server.xml) which is consumed by the said applications to keep the configuration container independent and to avoid direct file access from a web application. So far almost everything already works perfectly! Except that Tomcat obviously caches resources which are looked up via JNDI.
There is sort of a way to get this happen. It is not a cache, instead it is singleton or non singleton.
Take the default example that ships with Tomcat
<Resource name="UserDatabase" auth="Container" type="org.apache.catalina.UserDatabase" description="User database that can be updated and saved" factory="org.apache.catalina.users.MemoryUserDatabaseFactory" pathname="conf/tomcat-users.xml" />
With this configuration, getObjectInstance will only be called once. However, there is an attribute that can be set that will make sure that getObjectInstance is called every time a Context.lookup happens, it is singleton="false"
<Resource name="UserDatabase" auth="Container" type="org.apache.catalina.UserDatabase" description="User database that can be updated and saved" factory="org.apache.catalina.users.MemoryUserDatabaseFactory" pathname="conf/tomcat-users.xml" singleton="false"/>Then you are able to decide when getObjectInstance returns a new object, or a cached object in your own code.
answered by fhanik on January 7, 2013 04:55 PM
Ask the Experts : Apache Tomcat 7 Private byte increases and not releasing back
I have observed the tomcat 7 process memory (private bytes) was initially 1.2 GB during startup and it got increased to 3.5 GB where my server RAM size is only 4GB after running a 100 users test for 4 hours. this private bytes was not released even after stopping the test. could you please let us know any configurations that might help this or kindly analyze the situation and provide your suggestions/solutions.
Regards,
Raga
asked by Ragavendran
Lacking more specific about the behavior that you are seeing and about the environment that you are using to run your tests, and since this is a testing environment, my suggestion to you would be to run your tests while you have a profiler hooked up to Tomcat (YourKit is an excellent profiler). The profiler will allow you to look for memory problems in your application.
That's not to say there is definitely a problem here. It is entirely possible that you could see the heap grow from 1.2 G to 3.5G legitimately. It just depends on your JVM options and the memory demands of your application.
answered by dmikusa on May 8, 2012 10:51 AM
Ask the Experts : Tomcat-jdbc pooling not detecting dead connections
We recently migrated to using the apache tomcat jdbc connection pooling.
We are using v1.1.0.1 of the connection pooling mechanism with tomcat 6.0.33 on Oracle 10g
Our connection pools are configured as follows:
asked by san9jay
add
testOnBorrow="true" validationQuery="select 1 from dual"
in order to validate your connections
answered by fhanik on May 10, 2012 08:39 AM
Ask the Experts : Validation not triggering when deployed into Tomcat
asked by alex
hi Alex, welcome to the world of Java.
My recommendation is that you run without the security manager. It is inherently complex to, and it's not where you start as a beginner.
Before even consider running with the security manager turned on, you need to evaluate your requirements if you even need it. In my experience, 9 out of 10 companies will not need it as they secure the environments where Tomcat runs instead. In shared environments with untrusted parties, such as a shared hosting environment, the security manager comes in handy as it can protect against code.
So, to get started, turn off the security manager, and get your application fully working. The security manager is not a feature of Apache Tomcat, it's part of the Java Runtime Environment.
best
Filip
answered by fhanik on June 28, 2012 07:39 AM
Ask the Experts : Is Apache tomcat 6.0 and 7.0 are windowsserver 2008 64bit and vmware esx 5 compatible
Hello,
After lots of research, I cannot find the answer. Can you tell me if Apache tomcat 6.0 and 7.0 are windowsserver 2008 64bit and vmware esx 5 compatible?
Thank you
asked by Chris424
There is really no issue of compatibility between Tomcat and these products. Tomcat 6 & 7 run on the JVM and will run just fine on any system which has a capable implementation of the JVM.
Given that Oracle releases a 64 bit version of the JVM for Windows, you should have no problem running Tomcat 6 or 7 on Windows Server 2008 64-bit.
As for VMware ESX5, you may want to take a look at this link [1]. It documents the best practices for running any Java application, Tomcat 6 & 7 included, on VMware virtualization.
[1] - http://www.vmware.com/resources/techresources/1087
answered by dmikusa on February 20, 2012 08:21 AM
Ask the Experts : Null pointer in manager web app. Tomcat 6.0.14
I'm using Tomcat 6.0.14 as part of a cognos product installation. I'm following the installation guide. After installing the product and edit the configuration files, I need to deploy a war and a ear files using de Tomcat Manager application. Trying to log on as the System manager the server returns the following error:
HTTP Status 500 -
type Exception report
message
description The server encountered an internal error () that prevented it from fulfilling this request.
asked by Ucat
You need to upgrade your Tomcat version. Besides the fact that 6.0.14 is incredibly old and missing many security fixes, it appears that this bug has been fixed.
From the link you posted:
">My post is actually a bug report. Not a question.
Those NPEs have been fixed in svn and will be in the next release. "
http://markmail.org/message/zalrgnbb7frvfwgj
answered by dmikusa on February 20, 2012 08:25 AM
Ask the Experts : catalina.out log rotation
Hi,
I am interested in catalina.out log file rotation, I have an application where logging to catalina.out is very huge, say 0.5 MB / sec.
So I have written one script to handle this which is shown below.
# crontab -l | grep catalina
0,30 * * * * bash /catalina_log_handler.sh >/dev/null 2>&1
# more /catalina_log_handler.sh
#!/bin/sh
CATLOC=/bin/cat
SEDLOC=/usr/bin/sed
asked by akshay_tomcat
The catalina.out file is created by a shell redirection, ex ">> catalina.out 2>&1". This catches anything written to System.out and System.err and places it into the catalina.out file.
Given this, a good way to rotate catalina.out is to alter the script to pipe the output to a log rotation script rather than directly to a file. This will allow you to rotate the logs without restarting Tomcat and without copying the entire contents of the log to another file.
It's a pretty simple change to catalina.sh and it is described at this link.
http://marc.info/?l=tomcat-user&m=105640876032532&w=2
answered by dmikusa on February 20, 2012 08:27 AM
Happening Now on TomcatExpert
- graceh commented Apache Tomcat 6.0.37 Released
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