Develop Reference

Java EE web application performance tuning

I need to do a performance analysis of Java EE web application and optimize the code.
Please suggest ways of doing it?
To start with, I am checking the server logs.

Based on your vague question an answer can just be vague:
Depending on what you want to improve, the first rule is to measure what you want to improve. Furthermore alsways measure again after you tried to improve!
Memory
Regarding memory optimizations you should acquire heap dumps of the running application and analyze those. A very helpful tool for an anylysis is the eclipse memory analyzer tools.
Profiling
If you want to improve the performance and minimize runtime of code, you should start with profiling. JVisualVM is then a good tool. To get some load on your application JMeter can help you in the context of a web based application.
Rules of Performance tuning
First measure to identify the bottlenecks, then pick the "biggest" leaks for optimization. After optimizing measure again to verify your result. If you are not happy afterwards, start again with measuring.
Know the real slow parts of your application
Before even starting with measuring you should exactly identify the situations where your application is really slow, otherwise you might not notice a difference or even "de-optimize".

Use some good java profiler and figure out problem points like high memory usage, high CPU usage etc.
Look at YourKit and/or jprofiler. You can use their trial version for your case

Multiple tools are available to do performance analysis.
You can use Jmeter to do some load testing and see what performance you are getting. If you find performance bad for certain features then dig into that to find the bottlenecks.
You can use JProfiler to analyse JVM of the web application.

Try using a application monitoring tool like newrelic , it will tell you which server side components have the slowest response times, and then it will let you drill down to which calls within that application consume the most resources, that should be a good start ...

Steps involved in profiling java applications

Please explain about the steps involved in profiling a JAVA application? This is irrespective of what ever profiling tools that is used. What are the best practices and steps involved in profiling the java applications?
Experts, any links or documents are really appreciated.
Thanks.
Thanks. The thing I want to know is there are so many profilers available but when we profile a Java applications for OutOfMemory or Memoryleaks , etc . What are the steps we need to go through in profiling the application. Let say I am using VisualVM which does have a profiler , I am getting an OutOfMemory Error in my application my application so huge that I don't know where exactly is the problem even the logger is of no use (just for assumption). In such case how we can figure out where exactly is the problem by using the profiler tool like VisualVM? And what are the steps we need to look into ? Whether we can directly use the CPU and Memory profiling or still we need to go and get the thread dump and analyse it , then create a Heap dump analyze it and then go for a CPU and Memory profiling? I am little confused here. Hence please point me to the right direction as well as the steps involved in profiling a JAVA application to find the memory leaks. Hope I am clear with my question.

Depending on why you need to profile your application you have to decide what filters you will need, as mentioned inthe comments the question is very general, you should provide some more percise information to get some help hier.
Try the following link (in Eclipse):
An introduction to profiling Java applications
And check this List or Open source java profilers

i have used JProfiler and yourkit but i am not satisfied with output for actual performance tuning. currently we have been switched to java melody. This not only help performance optimization in dev but also in production system. Java melody is very easy to integrate and configure and in production you can enable or disable by just updating web.xml

This series of articles should give you a good idea on how you go about serious performance investigation of a relatively complex Java application.
http://www.jinspired.com/solutions/case-studies/scala-compiler

Java Profiling on Linux

I have a fairly complex Java application that is utilizing a lot of CPU, and would like to know if there is any recommendation on a profile tool that I could use to determine the cause of the CPU utilization. My goal is to pinpoint the location in the code where it is using most of the CPU time.

I've used jProfiler and YourKit on Linux. But you might find the information you're looking for by running the jconsole that comes with recent JDKs. Good information on how to use it: http://java.sun.com/developer/technicalArticles/J2SE/jconsole.html

Netbeans has good built-in profiler. NB runs quite well on Ubuntu 9.10
If your issue cannot be observed in developement, you can attach the profiler to a remote JVM (your production environment). You have to configure the host JVM to accept the JMS/JConsole connections from the profilers. The JMS/JConsole realtime monitoring visualization charts look pretty awesome.

I have used Visual VM in the eclipse IDE. If you are not on an IDE, jhat and jconsole will help. Google jhat for more info

If you are comfortable with Eclipse, I'd recommend TPTP.

If you use Sun Java 6 then learn to use jvisualvm in the JDK on the machine running the troublesome program.
It will answer most of your questions, can attach effortlessly to an already running program and is gratis.

This method is low-tech but works best. Here's a short explanation why.
Since you are not running under an IDE, you can use pstack or lsstack to get stack samples. If the app is using lots more time than it should, then most likely the problem is one or a few rogue function calls, which will be clearly visible on most of the stack samples.

Performance Cost of Profiling a Web-Application in Production

I am attempting to solve performance issues with a large and complex tomcat java web application. The biggest issue at the moment is that, from time to time, the memory usage spikes and the application becomes unresponsive. I've fixed everything I can fix with log profilers and Bayesian analysis of the log files. I'm considering running a profiler on the production tomcat server.
A Note to the Reader with Gentle Sensitivities:
I understand that some may find the very notion of profiling a production app offensive. Please be assured that I have exhausted most of the other options. The reason I am considering this is that I do not have the resources to completely duplicate our production setup on my test server, and I have been unable to cause the failures of interest on my test server.
Questions:
I am looking for answers which work either for a java web application running on tomcat, or answer this question in a language agnostic way.
What are the performance costs of profiling?
Any other reasons why it is a bad idea to remotely connect and profile a web application in production (strange failure modes, security issues, etc)?
How much does profiling effect the memory foot print?
Specifically are there java profiling tools that have very low performance costs?
Any java profiling tools designed for profiling web applications?
Does anyone have benchmarks on the performance costs of profiling with visualVM?
What size applications and datasets can visualVM scale to?

OProfile and its ancestor DPCI were developed for profiling production systems. The overhead for these is very low, and they profile your full system, including the kernel, so you can find performance problems in the VM and in the kernel and libraries.
To answer your questions:
Overhead: These are sampled profilers, that is, they generate timer or performance counter interrupts at some regular interval, and they take a look at what code is currently executing. They use that to build a histogram of where you spend your time, and the overhead is very low (1-8% is what they claim) for reasonable sampling intervals.
Take a look at this graph of sampling frequency vs. overhead for OProfile. You can tune the sampling frequency for lower overhead if the defaults are not to your liking.
Usage in production: The only caveat to using OProfile is that you'll need to install it on your production machine. I believe there's kernel support in Red Hat since RHEL3, and I'm pretty sure other distributions support it.
Memory: I'm not sure what the exact memory footprint of OProfile is, but I believe it keeps relatively small buffers around and dumps them to log files occasionally.
Java: OProfile includes profiling agents that support Java and that are aware of code running in JITs. So you'll be able to see Java calls, not just the C calls in the interpreter and JIT.
Web Apps: OProfile is a system-level profiler, so it's not aware of things like sessions, transactions, etc. that a web app would have.
That said, it is a full-system profiler, so if your performance problem is caused by bad interactions between the OS and the JIT, or if it's in some third-party library, you'll be able to see that, because OProfile profiles the kernel and libraries. This is an advantage for production systems, as you can catch problems that are due to misconfigurations or particulars of the production environment that might not exist in your test environment.
VisualVM: Not sure about this one, as I have no experience with VisualVM
Here's a tutorial on using OProfile to find performance bottlenecks.

I've used YourKit to profile apps in a high-load production environment, and while there was certainly an impact, it was easily an acceptable one. Yourkit makes a big deal of being able to do this in a non-invasive manner, such as selectively turning off certain profiling features that are more expensive (it's a sliding scale, really).
My favourite aspect of it is that you can run the VM with the YourKit agent running, and it has zero performance impact. it's only when you connect the GUI and start profiling that it has an effect.

There is nothing wrong in profiling production apps. If you work on distributed applications, there are times when a outofmemory exception occurs in a very unique probability scenario which is very difficult to reproduce in a dev/stage/uat environment.
You can try using custom profilers but if you are in a hurry and plugging in/ setting upa profiler on a production box will take time, you can also use the jvm to take a memory dump(jvms memory dump also gives you thread dump)
You can activate the automatic generation on the JVM command line, by using the following option :
-XX:+HeapDumpOnOutOfMemoryError
he Eclipse Memory Analyzer project has a very powerful feature called “group by value”, which makes it possible to build an object query and regroup the instances by a field value. This is useful in the case where you have a lot of instances that are containing a smaller set of possible values, and you can to see which values are being used the most. This has really helped me understand some complex memory dumps so I recommend you try it out.

You may also consider using one of the modern HotSpot JVM - Java Flight Recorder and Java Mission Control. It is a set of tools that allow you to collect low-level runtime information with the CPU overhead about 5% (I cannot prove the last statement anyhow, this is the statement of Oracle engineer who presented the feature and live demo).
You can use this tool as long as your application is running 1_7u40 JVM or higher. To enable the runtime info collection, you need to start JVM with particular flags:
By default, JFR is disabled in the JVM. To enable JFR, you must launch your Java application with the -XX:+FlightRecorder option. Because JFR is a commercial feature, available only in the commercial packages based on Java Platform, Standard Edition (Oracle Java SE Advanced and Oracle Java SE Suite), you also have to enable commercial features using the -XX:+UnlockCommercialFeatures options.
(Quoted http://docs.oracle.com/javase/8/docs/technotes/guides/jfr/about.html#sthref7)
I added this answer as this is viable option for profiling in production IMO.
Also there is an Eclipse plugin that supports JFR and JMC and capable of displaying information user-friendly.

The tools have improved vastly over the years. These days, most people who have needs like these use a tool that hooks into Java's instrumentation API instead of the profiling API. Surely there are more examples, but NewRelic and AppDynamics come to mind. Instrumentation-based solutions usually run as an agent in the JVM and constantly collect data. They report the data at a higher level (business transaction, web transaction, database transaction) than the old profiling approach and allow you to dig deeper (down to the method or line) if necessary. You can even setup monitoring and alerts, so you can track/alert on metrics like page load times and performance against SLAs. With these great tools, you really should have no reason to run a profiler in production any longer. The cost of running them is negligible.

Java profiler for IBM JVM 1.4.2 (WebSphere 6.0.2)

I'm looking for a Java profiler that works well with the JVM coming with WebSphere 6.0.2 (IBM JVM 1.4.2). I use yourkit for my usual profiling needs, but it specifically refuses to work with this old jvm (I'm sure the authors had their reasons...).
Can anybody point to a decent profiler that can do the job? Not interested in a generic list of profilers, BTW, I've seen the other stackoverflow theread, but I'd rather not try them one by one.
I would prefer a free version, if possible, since this is a one-off need (I hope!) and I would rather not pay for another profiler just for this.

Old post, but this may help someone. You can use IBM Health Center which is free. It can be downloaded standalone or as part of the IBM Support Assistant. I suggest downloading ISA since it has a ton of other useful tools such as Garbage Collection and Memory Visualizer and Memory Analyzer.

What are you looking to profile? Is it stuff in the JVM or the App Server? If it's the latter, there's loads of stuff in WAS 6 GUI to help with this. Assuming you really want to see stuff like the heap etc, then the IBM HeapAnalyzer might help. There are other tools listed off the bottom of this page.
Something else I've learned, ideally, youll be able to connect your IDE's profiler to the running JVM. Some let you do this to a remote one as well as the local one you are developing on. Is the JVM you wish to profile in live or remote? If so, you might have to force dumps and take them out of the live environment to look at at your leisure. Otherwise, set up something local and get the info from it that way.

Update: I found out that JProfiler integrates smoothly with WAS 6.0.2 (IBM JDK 1.4).