Hello Experts,
I really need your help in understanding Heap dumps.
In our company .. very frequently we have an out of memory issue which is automatically generating heap dumps (abcd.hprof).
Somebody asked me
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if you can analyze the heap dump to understand the reason for JVM crash.
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So in which way should I answer the above question. ( I am very new to the heap dumps & Garbbage collection concepts)
Also what can be analysed with this abcd.hrof file. Can you tell me what are terms need to be specified when I respond back to that question?
I have loaded this file into VISUAL GC & VISUAL VM tool. but was not able to understand abit, Should I send them a graph which is taken from visual GC ?
or else can you suggest me a better tool to analyse heap dumps
(I am an Application engineer not a developer )
Please help me...
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@ appadmin
1. First check if its from Sun JVM or IBM JVM or BEA JVM.
2. If its IBM JVM, download their memoryanalyzer program and load your heapdump. It would take time based on the size of the dump.
3. If its Sun or BEA, you can try loading your heapdump through JProfiler or Yourkit.
Personally, I have tried latest version of Yourkit and found it to be lightweight than JProfiler. All the best.
@Rajesh
Thanks for suggesting me very nice tool, My initial doubt is clear regarding the tool,
We are using SUN JVM so I have download YOURKIT and loaded the ***.hprof heapdump file into YOURKIT, So what are the things that I need to analyse at this point to understand the reason for JVM crash.
Also in what terms do I need to explain the reason for JVM crash based upon the analysis,
Have also attached the snapshots of heapdump which was loaded into YOURKT.
Hi Appadmin,
Your H1.png is useful. Rest of them are specific to a class. It looks like you are having almost 384MB of data stored in HashMap. That is really huge. I guess you might be having 512 or 1 GB RAM for your JVM??
Given that, the ratio of HashMap size seems to be heavy. You might want to click on that HashMap and "click to start collection" in bottom pane. That would let u drill down what is taking more space inside hashmap.
My feeling is that, you might have com.*.CanonicalObjectEntry
All the best. :)
Thanks Rajesh, you are absolutely correct we have 1 GB RAM.
So when ever I have the heap dump, do i need to analyse only HashMap or else need to start analysing based upon the Retained size coloumn in yourkit.
Also I have clicked on that HashMap and "click to start collection" in bottom pane took the snap shot.. can we analyse anything at this time.
start collection
As per 1st image, looks like your HashMap contents are really expensive. Yes, retained size will take sometime to compute. So give it sometime after opening the dump. Based on your computing power, it will take 2 or 3 minutes to compute the retained size.
Retained size gives the size of your hashmap along with its contents. So you would be able to see it in the bottom pane.
If its a leak, mostly the same pattern would emerge and dev should be able to nail it down the contents of the map.
Business Accounts
Answer for Membership
by: gurvinder372Posted on 2009-10-02 at 03:18:58ID: 25476504
Did you tried to use this
http://java.sun.com/develo
This link may also answer some of your questions.