How do I programmatically find out my PermGen space usage?

Question

I'm trying to diagnose a java.lang.OutOfMemoryError: PermGen Space error when running on Sun's Hotspot JVM, and would like to know how much PermGen space my program is using at various points. Is there a way of finding out this information programmatically?

Answer 1

You can use something like this:

Iterator<MemoryPoolMXBean> iter = ManagementFactory.getMemoryPoolMXBeans().iterator();
while (iter.hasNext())
{
    MemoryPoolMXBean item = iter.next();
    String name = item.getName();
    MemoryType type = item.getType();
    MemoryUsage usage = item.getUsage();
    MemoryUsage peak = item.getPeakUsage();
    MemoryUsage collections = item.getCollectionUsage();
}

This will give you all types of memory. You are interested in "Perm Gen" type.

Answer 2

Try ManagementFactory.getMemoryPoolMXBeans().