Re: Memory utilization
On Jan 30, 2:54 am, ghostwhoowa...@gmail.com wrote:
I was trying to profile the following piece of code using NetBeans:
public static void main(String[] args)
{
Map<String, String> map = new HashMap<String, String>();
for( int i = 0; i < Integer.MAX_VALUE; ++i )
{
map.put(Integer.valueOf(i).toString(),
Integer.valueOf(i).toString());
}
}
I set my max and min heap size to be 1GB. I find that the program dies
after having created 4M entries (at which point the heap used is at
1GB) although the memory used by the objects as indicated by the
Netbeans memory profiler is the following:
String -- 48MB
char[] -- 48 MB
HeapCharBuffer -- 45MB
Integer -- 19MB
HashMap$Entry -- 19MB
This totals to less than 200 MB and the rest of the objects are at 0%
of the total used memory at most another 200MB. How come the heap
usage is at 1GB at this point of time? I am extremely confused. Could
someone please explain what might be going on?
Thanks
A
Something is VERY wrong here:
"4M entries" in Map<String, String> will mean 8M String(s) - each
String has an OVERHEAD of 40bytes (AFAIK) - this alone should give you
320MB heap usage even when ALL String(s) are empty.