by Karun Subramanian
on October 30, 2014
Alright. Now let us dive into step-by-step procedure on actually analyzing the Thread Dump.
Step by Step procedure to analyze a Thread dump
1. Open the Thread dump in your favorite text editor.
Note: Java Threadump (aka javacore) is generally a text file that can be opened using any text editor. If you cannot open it, chances are it is not a JVM thread dump. Perhaps you are trying to open a heap dump or an Operating System core file.
2. Search for the string RUNNABLE. If you are running IBM JVM, look for the string “state:R”.
3. There can be lot of RUNNABLE threads. What you want to do is pay attention to the Threads that are running your application code. They will be evident from stack trace. Look for com.<companyname>.<packagename>.<classname>.<methodname>. You can ignore Application Server specific Threads. It is not unusual to see tons of Application Server threads (for example listen sockets) in the Thread dump.
Example: The Thread below is clearly NOT running your application code at that moment
because it does not show any “com.<companyname>.<packagename>.<classname>.<methodname” in its stack trace.
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by Karun Subramanian
on October 26, 2014
Okay. Now that you have some fundamentals drilled in, let us look at how exactly to take the Thread Dump. But even before that, let us answer this question:
Does taking Thread dump kill the Application Server? Are there any side effects?
When you take the Thread dump, the JVM is momentarily paused to dump the stack. This does mean that the JVM is interrupted. But that’s about the effect taking the Thread dump should have on the JVM – a momentary pause. However since it is somewhat intrusive process, there is an extremely rare possibility that it does something adverse to the JVM, like getting aborted. But in practice the cases like this are virtually none.
How do you take a Thread Dump of a JEE Application Server?
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by Karun Subramanian
on October 25, 2014
‘Threads’ is perhaps the most misunderstood component among Application support engineers and even among Software Developers. Take a look at the following questions that we typically come across in our glorious support career:
- What does it mean to say ‘There must be hung Threads’ in the Application?
- Have you exhausted the available Threads in Application Server?
- Which Thread Pool is used for Web Container?
- Do I have to configure the number of JDBC Connections in the connection pool equal to the number of Threads I have in the Application Server?
- How can I find out which thread is currently running in the Application Server?
- Is ‘number of Threads’ configurable? Can I have unlimited Threads?
- How can I find out all Threads that are currently running?
- Is there a Thread Dead Lock going on?
- How can I kill hung Threads?
Well, after going through this three part series, you will be able to answer all the above questions.
What is a Thread?
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by Karun Subramanian
on September 11, 2014
Recently, I had the privilege to talk to Sri Chaganty, CTO and co founder of AppEnsure.
AppEnsure is probably the newest (as of Sep 2014) APM vendor entering this competitive yet lucrative market. As Sri walked me through the product, I had several ‘Wow, that’s way too cool’ moments. In this article, I would like to share some of the features that I thought were brilliant.
1. Up and running in minutes
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by Karun Subramanian
on September 9, 2014
The truth. If you don’t have a reliable APM (Application Performance Management) solution implemented in your environment, you are walking on a minefield. You never know when that Application Server is going to crash, or when that File server is going to run out of space or when that Web Server is going to run out threads and be a victim to a DOS attack. Simply put, you want to know about an issue before your customer does. Period. A dependable APM solution and help you do just that.
In this article, I would like to answer some of the very basic yet critical questions in the field of APM. Specifically, I will explain the following:
1. What is an APM solution ?
2. How a reliable APM can help you increase your profits ?
3. How to find the right APM solution ?
4. How to implement the chosen APM solution ?
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by Karun Subramanian
on August 3, 2014
Have you ever tried to find out the entire command line arguments for the ‘java’ command that starts your application in Windows ? Have you ever tried to find out which files or DLLs are opened by your Java Application in Windows ? The Windows Task Manager is OK but it does not give you the deeper insight that you would need to answer the above questions. Welcome to Process Explorer.
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by Karun Subramanian
on July 30, 2014
Oracle’s latest edition of the world’s biggest software platform, Java 8 was released on March 2014. Here are the 5 things you need to know about this edition of this marvelous language.
1. Introduction of Lambda Expressions.
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by Karun Subramanian
on July 27, 2014
Let’s face it. Nobody likes a slow application. It is our job to make sure our applications fulfill the functionality need completely, but at the same time delivers good user experience.
In 16 years of my experience in technical support primarily in the world of JEE, while I cannot honestly say ‘I have seen it all’, I can say “I have seen a lot“. Here are the top 10 reasons why your Java application may slow.
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by Karun Subramanian
on July 20, 2014
Oracle’s latest edition for Java – Java 8 was released in March 2014. As usual, tons of new features have been added. There is one major change in the Memory management area that I want to discuss today.
“So long PermGen, Hello Metaspace !!”
Oracle has completely gotten rid of ‘PermGen’ and replaced it with Metaspace.
What is PermGen ?
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by Karun Subramanian
on July 16, 2014
So, when was the last time you monitored the CPU utilized by your Java application ? Perhaps ‘never’ ?. It is actually important to keep an eye on the CPU utilzied by your application. Your Application runs on a host (or hosts) that has one or more CPUs managed by the Operating System. The CPU resource is not unlimited (even though some developers and Administrators wish that were true).
Let’s dive into the 4 things you need to know about the CPU Utilization of your Java application.
1. Why do you care ?
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