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Questions tagged [heap-dump]

A heap dump is a snapshot of the memory of a Java process.

A heap dump is a snapshot of the memory of a Java process.

The snapshot contains information about the Java objects and classes in the heap at the moment the snapshot is triggered. Because there are different formats for persisting this data, there might be some differences in the information provided. Typically, a full garbage collection is triggered before the heap dump is written, so the dump contains information about the remaining objects in the heap.

All Objects: Class, fields, primitive values, and references.

All Classes: Class loader, name, super class, and static fields.

Garbage collection roots: Objects defined to be reachable by the JVM.

Thread Stacks and Local Variables: Call-stacks of threads at the moment of the snapshot, and information about local objects on a frame by frame basis.

A heap dump does not contain allocation information, therefore you cannot work out what created the objects or where the objects were created.

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Get byte array data from openj9 heap hump

I acquired a heap dump from a OpenJ9 java application using the command jcmd GC.heap_dump Then I open it on Eclipse Memory Analyzer to check a specific class, but when I tried to see the content of a byte array attribute of this class all…
Anderson Fachini
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How can a jmap live heap dump contain unreachable objects?

I used jmap to dump the live heap of an application using CMS GC: jmap -dump:live,format=b,file=heap.hprof I opened this dump with YourKit and it found that 61% of the 8Gb heap was unreachable, specifically Objects unreachable from GC roots,…
Graeme Moss
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How to check that java heap is fragmented?

I have a 29G heap dump, created by Hotspot VM after OutOfMemoryError occurred. Heap analyzer (I use YourKit) showed that all objects (including unreachable) take 26G. My guess is remaining 3G are wasted because the heap is fragmented. Is there a way…
Sergey Fedorov
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Low throughput of service due to frequent Garbage Collection

I have a service running on a system with 16GB RAM with following configurations :…
AkaSh
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Need to fetch value from array for each index in MAT

Need to fetch value from array for each in MAT SELECT a.table[0].value.specVersion.value FROM OBJECTS 742325 a In above query, i am able to get the value on specific index but i want run in loop to fetch value for every index in an array.
Chetan Anand
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JSoup Objects not Garbage Collected causing outofmemoryexception

I'm using JSoup to parse HTML from pages I scrape. After long-term usage of the program, I kept seeing my RAM increase. When somebody using my program as well mentioned an out of memory exception I decided to see where the issue lies using…
daisyodland
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Give read permission to others for HeapDumpOnOutOfMemoryError file .hprof on generated

I start my java with these arguments -XX:+HeapDumpOnOutOfMemoryError -XX:HeapDumpPath=/log/${SERVICE}_`date +%Y-%m-%d:%H:%M:%S`.hprof" When heap dump occurs, the .hprof file has -rw------- (600) permission, which can't be read by other users. How…
hydradon
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How to figure out memory leak in node process

My nodejs application is leaking memory, so I was trying to use heapdump to compare the memory changes, unfortunately, memory does not change in headdump, but my nodejs process is leaking memory.So I was thinking native-modules could be one culprit,…
Wonderful
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Lots of StandardSession objects in the heap

I am investigating a heap dump for a web application based on java 6 running on Tomcat 6 using eclipse MAT and I noticed that objects of org.apache.catalina.session.StandardSession has occupied majority of the heap. Actually there are about 400…
Ferez
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Can I open custom hsperfdata_root/PID after process shutdown?

I'm using docker to containerize my application and want to look at it's performance from host machine. I've mapped volume : "/opt/tmp/my_app/:/tmp", which contains hsperfdata_root Can I somehow open heap and other information from that…
Hejwo
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Issue Taking Java Heap Dump

I'm trying to take a java heap dump to help investigate a memory leak. Whenever I use this: jmap -J-d64 -dump:format=b,file=myheapdump -F 29498 The heap dump file gets to about 16,048 kb and stops growing, jmap will run forever and not stop unless…
jymbo
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Heap dump vs gcore dump and how to analyse the output

What is the difference between heap dump and gcore core dump ? I am trying to analyze a running process that's growing in memory, If I do a core dump using gcore is it possible to convert it to heap dump ? Are there any tools to analyse core/heap…
Praveen
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Convert .dmp file to .hprof file

I have tried running the command jmap -dump:format=b,file=jvm.hprof core.20170103.212745.20453.0007.dmp But i get an error Error attaching to remote server: java.rmi.UnknownHostException: Unknown host: core.20170103.212745.20453.0007.dmp; nested…
Prateek Narendra
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Java Heap not full but still getting error java.lang.OutOfMemoryError: Java heap space

I have this strange issue going on in my one of production application. I have checked the heap space on the server and do not found any anomalies (Please see below screen) but still i am getting the error below on few operations that my application…
nikhilgupta86
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Why StatefulSessionComponent cause a memory leak?

Because of a Java Heap Space error I did a heap dump of my Java EE 7 program running on a WildFly 9 server. Then I used Eclipse Memory Analyser to analyse the dump. Eclipse Memory Analyser reveals the 2 following problems which are the same: One…
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