About to choose hosting service for a website written in GWT with Java on the server side.
Does anyone have some good guidelines for JVM mem settings. Some hosting services are limiting JVM memory. I was told one JVM per CPU core but what about mem settings?
Best regards,
Niclas Lindberg
Multiple JVM will increase the memory footprint. We used to run single JVM even for 64 core machines. You need to tune your JVM parameters accordingly.
Please see the following links
http://docs.sun.com/source/817-2180-10/pt_chap5.html
http://javahowto.blogspot.com/2006/06/6-common-errors-in-setting-java-heap.html
It depends on the requirements of your app. You can start with a certain size, e.g:
-Xms512m -Xmx512m -XX:PermSize=128m -XX:MaxPermSize=256m
You need to monitor the JVM with JConsole and see if it is good enough. You can adjust the parameters according to your monitor result. Basically, -Xms should be equals with -Xmx which can reduce the CPU overhead for increasing heap size.
Related
I'm trying to figure out why Liberty is consuming CPU 100% when I enable dropins in my Liberty instance?
I tried the following (searched the Internet):
disabled dynamic polling of config and dropins
increased JVM heap size by adjusting Xms and Xmx
enabled -verbose:gc to see if there are any Garbage Collection activities
There are no GC activities, there is more than enough RAM in the system, however, CPU is at almost 100% when I enable dropins making the system and/or Liberty apps unusable.
This is on AIX 7.1 TL3 with 16 GB of RAM. Liberty is the latest 19.0.0.11, even though I tried this on 19.0.0.10 as well with the same results.
Any suggestions, as I'm out of ideas?
Thanks
I want to monitor JVM performance on my production environment. I have installed only JRE, not JDK, Hence i can't use jstat, jconsole etc. to monitor the JVM performance.
Can somebody please help to understand how can i monitor JVM performance in this scenario?
Is there any way to achieve this?
(please note that i don't want to monitor it remotely through JMX or something else. i would like to install local agent in each machine which will send the metrics to server at the interval of 1 minute.)
Thanks,
KS
If you manage to get JMX up and running on your VM (from the comment), you can then use jmxterm or jmxfetch to push these JMX metrics into a metrics system (like graphite or Datadog).
If you have enough patience and time to write, you can probably have a look at JVMTI. You can write your code in C/C++ and run it along your Java Process and you can gather information about the JVM without affecting it.
Another simple and naive way is to start your VM with a javaagent written in java but JVMTI is even better than that. The most crucial difference between the javaagent and JVMTI app is derived from the loading mechanics. While the agents are loaded inside the heap, they are governed by the same JVM. Whereas the JVMTI agents are not governed by the JVM rules and are thus not affected by the JVM internals such as the GC or runtime error handling.
You can even give Java Mission Control a try if you're using JDK7 or above :)
Jolokia is a java agent you can use to expose JMX as http. Run jmx2graphite and get those metrics into Graphite. The link includes instructions on Graphite installation (10 minutes)
I would like to attach to a WebSphere JVM and obtain useful data like garbage collectors' names and their collection counts, thread counts, heap/non-heap memory usage, JVM uptime etc. However, this link gives the list of MBeans available with the WebSphere JVM -
http://pic.dhe.ibm.com/infocenter/wasinfo/v6r1/index.jsp?topic=%2Fcom.ibm.websphere.javadoc.wsfep.doc%2Fweb%2FmbeanDocs%2Findex.html
These MBeans don't seem to offer any data that I require. Is there any other way to obtain the data? I shall be using JMX to gather it.
If you're a corporate with bucks to spend I would suggest a product like Wily Introscope which runs an agent along with your JVM to collect all the metrics that you are after. I have used it with Websphere servers. Searching for an Open Source alternative I came across GlassBox which may provide a low cost alternative for you.
I'm not aware of any default MBeans that will provide the coverage you're after. It's typically the big Java vendors that provide this type of functionality.
[Update]
Having done something recently using VisualVM with Websphere 7, for the purposes of real-time monitoring/troubleshooting, I thought I would share my knowledge. VisualVM comes with the standard Sun JDK and you will find it installed here: JAVA_HOME\bin\jvisualvm.exe
To enable the JRE in Websphere to allow VisualVM to connect you must add the following JVM parameters using the Websphere Admin Console
Go To: Application Servers > [server_name] > Java and Process Management > Process definition > Java Virtual Machine > Generic JVM arguments
-Djavax.management.builder.initial=
-Dcom.sun.management.jmxremote
-Dcom.sun.management.jmxremote.authenticate=false
-Dcom.sun.management.jmxremote.ssl=false
-Dcom.sun.management.jmxremote.port=1099
-Dcom.sun.management.jmxremote.local.only=false
Make sure that the port number you have chosen above is not already in use
netstat -ap | grep 1099
Restart the server and you will be able to connect using VisualVM to see Uptime, Threads, Heap and GC profiles.
I see that Sun have also documented how you can write your own Java JMX client to read these values.
You could go with the suggestions provided by Brad and Andreas.
I would like to give you some insights into some of the tools that should be explored
(1) Tivoli Performance Viewer. This should provide some information about the JVM.
(2) IBM Health Center -> http://www.ibm.com/developerworks/java/jdk/tools/healthcenter/
Both of these should provide you a lot of info that you require.
Try them out
The JVM statistics are provided by the platform MXBeans. If you need to collect this data over a short period of time, then you could use a tool such as VisualVM. It's a bit tricky to configure this to connect to a WebSphere instance, but it is possible. One way to do that (there are other options) is described here:
http://code.google.com/p/xm4was/wiki/VisualVMHowTo
If you want to collect the data over a longer period of time, then you need a monitoring system. At work, I wrote a plugin for the Open Source RHQ enterprise management system that adds support for WebSphere. I'm in the process of releasing this plugin as an Open Source project, but at the time of writing, I have not yet published the documentation and there is also no downloadable release yet. Only the source code is available right now. I will try to complete that in the next weeks. If you are interested in this project, please let me know.
What is the minimum amount of RAM that the Weblogic Admin Consoel (version 10.3.2) will run under?
256MB is usually a safe bet but for our larger production domains, we use as much as 512mb. In addition to the domain size, your WLDF settings can affect the required heap size.
On a test system, you can probably get away with 128mb.
4 GB
Setting the memory arguments for the WebLogic application servers for SAS® Financial Management
My Grails application is running in a development environment. I still didn't go into production, but in any case, is it normal that my Grails application is requiring 230 MB at startup only (with an empty bootstrap and no request handled so far)?
Do you know why this is the case, how to improve memory usage in development mode and, most important, whether it is reduced in production environment?
To answer your questions, yes - it is normal. It's especially normal if you have a lot GSPs in your application. GSPs are runtime compiled so you can speed up their generation by increasing your permgen space.
You can improve memory use and performance in general by making sure that you are passing the '-server' flag when you load your server JVM.
I wouldn't blame all that memory usage just on Grails. Because it uses an embedded Tomcat (Jetty in older versions) there will be a decent amount of overhead even when running an empty application.
IMO, 230MB is a lot of memory use for a Java application. High memory usage is just part of life when writing jvm based applications.
My online Grails applications run in a VPS with only 512MB (which includes a Drupal CMS, Apache, the email services, ... and the Tomcat to run GRails) so you can definitely tune your application to use less memory