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Jackson Tan

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since Jun 01, 2010
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Recent posts by Jackson Tan

Tim Holloway wrote:

Justin Rundle wrote:This solution does work but for a better understanding for myself why does this fix the issue and what causes this issue?



Apparently some of the saved session files were damaged somehow, possibly tomcat crached while writing them, possibly hardware problems. Since session files are not critical resources, the best solution was just to get rid of them.

Note that when I say "not critical resources", I mean that if you delete them while Tomcat isn't running, the user session will have been terminated when Tomcat restarts, so the user will effectively have been logged off and lost work in progress. They're DEFINITELY critical while Tomcat is running!



May I know any other cause of a corruption of saved session files? Can it be caused by the application code? please site some example for better understanding. Thanks
11 years ago
I have read to use verbose:gc to know the correct values of xmx and xms but I don't know how to read the logs of the verbose gc? Can someone help me in knowing the correct values for Xmx? or direct me to a tutorial link using verbose gc preferably a video tutorial.. Thanks.
11 years ago
Can you give me examples or some tips on finding memory leaks? How did you find the memory leaks that are dependent on the objects in your cache?
11 years ago
I have already thought of that solution to reboot the server once a week but I want to find the leak somewhere. I want to learn how to find leaks and I used YourKit Java Profiler for the object analysis. I attached a screenshot of the list of objects that retain sizes. The thing is there's so many objects I don't know how to debug.. I already watched videos and searched for tutorial about the profiling but the examples in tutorials are too simple and obvious because they have large size memory leaks. I think I only have small leak so I'm having a hard time finding it. Can someone help or direct me for a tutorial in finding memory leaks? Especially using YourKit Java Profiler bec I already installed it. Anyways thanks for the reply Tim.
11 years ago
Hi again, I have tested my application and again monitored its mem usage. Now, I accessed and processed transaction with my application. I processed about 20+ transactions and ran my application for about 5 hours. I think the app has a memory leak somewhere but I can't locate it. I used the YourKit Java Profiler tool to profile my app but I'm new to this and can't seem to find the leak. I don't know if traced the code correctly but I traced it to JAXBUtil and I don't know what to do especially that I didn't right the code for the JAXBUtil. I provided screenshots for the JAXBUtil, I hope someone can help me.. Thanks.

PS. I already Forced GC before getting the screenshots







11 years ago
I tested it only on my local, not on server. and yes it's connected to the internet. I will try to test again without internet connection. but is it possible that my application has a memory leak and that is the cause of this increasing memory usage even if in idle? Thanks
11 years ago
I attached another image below showing same application but I used/accessed the application during some time. In the chart below, I can see that from 1150-1250 I have again increasing memory usage. During this time, I didn't access the application but at 1251 onwards I access the application and the memory went back to normal again. Why is it that only during idle time of my application does the memory increase? Is it a problem in my application or the garbage collector? Thanks.

11 years ago
Hi, can someone help me. I have a j2ee web application. I want to monitor if it has a memory leak. I have a tomcat server that has only 1 deployed application I want to monitor. I ran the tomcat server last night and then run jconsole to monitor the memory usage of the application. After running the server, I didn't access the application. I left the server and the jconsole overnight in idle mode. This morning I saw that the memory usage of my application increases through time even if it is idle (no one accessing) See image below for the memory chart. I also force Garbage Collection in JConsole on the last part that's why memory went down on the last part of the chart. My question is does the memory chart say I have a memory leak in my application? But if I have a memory leak, why is it that after I perform GC the memory went down to normal. Any explanation or help will be appreciated. THanks

11 years ago