I run java program with -Xms512m -Xmx1G -Xss1G. I make profiling to verify the memory, so i Track every 10 object allocations. i observe this figure : My question is, why it display me that 117mo represent 40% while i give 1G to memory ? Answer The graph is a percentage of all allocations, not the heap size. …
Tag: heap-memory
UsageMemory threashold in JConsole
I am looking into how to use JConsole to detect memory leaks. I see that in Memory Pool in my MBeans I can define UsageThreashold for my Tenured Generation. So if my application exceeds this threashold the heap memory becomes red in the Memory tab. Question: How does this help? I mean how am I supposed to use…
Java Heap and Pass By Value
I am a little confused as to how my Java program is allocating memory. Below is a typical situation in my program. I have an object created on the Heap inside of a class which I pass to other functions inside of other classes. My question(s) are about how the memory is used. When A’s list gets passed to…
How to tell if one of the heap-generations is full?
We are experiencing some problems in our production environment, where we get an InvalidPropertyException from one of the compiled jsps (which one differs from time to time) after a bit of time. I have a suspicion that this is caused by something “disappearing” from the heap. Further, I suspect th…
Would writing a server in 64bit Java be stunted by JVM heapsize / memory?
It looks like 32 bit java program can only use between 1-2 gigs of ram? http://publib.boulder.ibm.com/infocenter/javasdk/tools/index.jsp?topic=%2Fcom.ibm.java.doc.igaa%2F_1vg00014884d287-11c3fb28dae-7ff6_1001.html Could I expect a java program running in 64bit OS to not have this limitation? Answer Could I ex…
Difference between sampling and profiling in jVisualVM
VisualVM has two separate tabs for sampling and profiling. What is the difference between sampling and profiling in VisualVM? Answer Sampling means taking lots of thread dumps and analyzing stack traces. This is usually faster, does not require runtime changes in your bytecode (which may break it), but is als…
Launching Processing.org App on Linux with Java Xmx
I have an application created with Processing.org and am trying to run it on Linux. Shortly into the app I get a Heap Size error. I am trying to run the app from the command shell with the line java -Xmx512m myAppNameHere but when I do this, I get a message that says “Exception in thread “mainR…
What is the recommended max level of heap memory usage? Recommended garbage collection time?
I recently found that one of my services was taking a large amount of time in garbage collection because the max heap size was too small. The service was there before I started, so I was unaware of the low heap size. I would like to set an alarm to warn me if it goes back up past a certain
is there a way to know which objects are in “old” area of Heap
I have long cycles of GC. from checks I saw there are too many objects in the tenured (old) area of the Heap. Is there any utitlity to know which objects are in which area of the heap, or any staticstics about these objects. I am using Sun/Oracle HotSpot JVM (Java 6). EDIT: little bit more details about my pr…
How to manage Heap Space in Java
I’m trying to recursively traverse through my Drive to search some files. The code is working fine when there are limited folders/files but when I target my search to C drive where in I have lots of files it throws Out of Heap memory. Exception in thread “Thread-4” java.lang.OutOfMemoryError…