How do I analyze a hprof file

Question

I have a production server running with the following flag  -XX  HeapDumpOnOutOfMemoryError  Last night it generated a java-38942 hprof file when our server encountered a heap error  It turns out that the developers of the system knew of the flag but no way to get any useful information from it   Any ideas

User · Accepted Answer

If you want a fairly advanced tool to do some serious poking around, look at the Memory Analyzer project at Eclipse, contributed to them by SAP.

Some of what you can do is mind-blowingly good for finding memory leaks etc -- including running a form of limited SQL (OQL) against the in-memory objects, i.e.

SELECT toString(firstName) FROM com.yourcompany.somepackage.User

Totally brilliant.

User · Answer

You can also use HeapWalker from the Netbeans Profiler or the Visual VM stand-alone tool  Visual VM is a good alternative to JHAT as it is stand alone  but is much easier to use than JHAT   You need Java 6  to fully use Visual VM

User · Answer

Just get the Eclipse Memory Analyzer  There s nothing better out there and it s free   JHAT is only usable for  toy applications

User · Answer

YourKit Java Profiler seems to handle them too

User · Answer

If you want to do a custom analysis of your heapdump then there s    JVM Heap Dump Analysis library https   github com aragozin jvm-tools tree master hprof-heap   This library is fast but you will need to write your analysis code in Java   From the docs    Does not create any temporary files on disk to process heap dump Can work directly GZ compressed heap dumps HeapPath notation

User · Answer

You can also use HeapWalker from the Netbeans Profiler or the Visual VM stand-alone tool  Visual VM is a good alternative to JHAT as it is stand alone  but is much easier to use than JHAT   You need Java 6  to fully use Visual VM

User · Answer

I personally prefer VisualVM  One of the features I like in VisualVM is heap dump comparison  When you are doing a heap dump analysis there are various ways to go about figuring out what caused the crash  One of the ways I have found useful is doing a comparison of healthy vs unhealthy heap dumps   Following are the steps you can follow for it      Getting a heap dump of OutOfMemoryError let s call it  oome hprof   You can get this via JVM parameter HeapDumpOnOutOfMemoryError  Restart the application let it run for a big  minutes hours  depending on your application  Get another heap dump while the application is still running  Let s call it  healthy hprof   You can open both these dumps in VisualVM and do a heap dump comparison  You can do it on class or package level  This can often point you into the direction of the issue     link   https   visualvm github io

User · Answer

If you want to do a custom analysis of your heapdump then there s    JVM Heap Dump Analysis library https   github com aragozin jvm-tools tree master hprof-heap   This library is fast but you will need to write your analysis code in Java   From the docs    Does not create any temporary files on disk to process heap dump Can work directly GZ compressed heap dumps HeapPath notation

User · Answer

You can use JHAT  The Java Heap Analysis Tool provided by default with the JDK   It s command line but starts a web server browser you use to examine the memory   Not the most user friendly  but at least it s already installed most places you ll go   A very useful view is the  quot heap histogram quot  link at the very bottom  ex   jhat -port 7401 -J-Xmx4G dump hprof jhat can execute OQL  quot these days quot  as well  bottom link  quot execute OQL quot

User · Answer

You can use JHAT  The Java Heap Analysis Tool provided by default with the JDK   It s command line but starts a web server browser you use to examine the memory   Not the most user friendly  but at least it s already installed most places you ll go   A very useful view is the  quot heap histogram quot  link at the very bottom  ex   jhat -port 7401 -J-Xmx4G dump hprof jhat can execute OQL  quot these days quot  as well  bottom link  quot execute OQL quot

User · Answer

I personally prefer VisualVM  One of the features I like in VisualVM is heap dump comparison  When you are doing a heap dump analysis there are various ways to go about figuring out what caused the crash  One of the ways I have found useful is doing a comparison of healthy vs unhealthy heap dumps   Following are the steps you can follow for it      Getting a heap dump of OutOfMemoryError let s call it  oome hprof   You can get this via JVM parameter HeapDumpOnOutOfMemoryError  Restart the application let it run for a big  minutes hours  depending on your application  Get another heap dump while the application is still running  Let s call it  healthy hprof   You can open both these dumps in VisualVM and do a heap dump comparison  You can do it on class or package level  This can often point you into the direction of the issue     link   https   visualvm github io

User · Answer

You can use JHAT  The Java Heap Analysis Tool provided by default with the JDK   It s command line but starts a web server browser you use to examine the memory   Not the most user friendly  but at least it s already installed most places you ll go   A very useful view is the  quot heap histogram quot  link at the very bottom  ex   jhat -port 7401 -J-Xmx4G dump hprof jhat can execute OQL  quot these days quot  as well  bottom link  quot execute OQL quot

User · Answer

Just get the Eclipse Memory Analyzer  There s nothing better out there and it s free   JHAT is only usable for  toy applications

User · Answer

You can use JHAT  The Java Heap Analysis Tool provided by default with the JDK   It s command line but starts a web server browser you use to examine the memory   Not the most user friendly  but at least it s already installed most places you ll go   A very useful view is the  quot heap histogram quot  link at the very bottom  ex   jhat -port 7401 -J-Xmx4G dump hprof jhat can execute OQL  quot these days quot  as well  bottom link  quot execute OQL quot

User · Answer

YourKit Java Profiler seems to handle them too

User · Answer

You can also use HeapWalker from the Netbeans Profiler or the Visual VM stand-alone tool  Visual VM is a good alternative to JHAT as it is stand alone  but is much easier to use than JHAT   You need Java 6  to fully use Visual VM

User · Answer

Just get the Eclipse Memory Analyzer  There s nothing better out there and it s free   JHAT is only usable for  toy applications

User · Answer

Just get the Eclipse Memory Analyzer  There s nothing better out there and it s free   JHAT is only usable for  toy applications

User · Answer

You can also use HeapWalker from the Netbeans Profiler or the Visual VM stand-alone tool  Visual VM is a good alternative to JHAT as it is stand alone  but is much easier to use than JHAT   You need Java 6  to fully use Visual VM

[java] How do I analyze a .hprof file?

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