Heap
The Java virtual machine heap is the area of memory used by the JVM, specifically HotSpot, for dynamic memory allocation. The heap is divided into generations:
- The young generation stores short-lived objects that are created and immediately garbage collected.
- Objects that persist longer are moved to the old generation (also called the tenured generation).
- The permanent generation (or permgen) is used for class definitions and associated metadata.
Originally there was no permanent generation, and objects and classes were stored together in the same area. But as class unloading occurs much more rarely than objects are collected, moving class structures to a specific area allows significant performance improvements.
Read more about this topic: Java Virtual Machine
Famous quotes containing the word heap:
“Mortality, behold, and fear,
What a change of flesh is here!
Think how many royal bones
Sleep within this heap of stones,
Hence removed from beds of ease,
Dainty fare, and what might please,”
—Francis Beaumont (1584-1616)
“A heap of epithets is poor praise: the praise lies in the facts, and in the way of telling them.”
—Jean De La Bruyère (1645–1696)
“—First a shiver, and then a thrill,
Then something decidedly like a spill,—
And the parson was sitting up on a rock,
At half-past nine by the meet’n’-house clock,—
Just the hour of the Earthquake shock!
MWhat do you think the parson found,
When he got up and stared around?
The poor old chaise in a heap or mound,
As if it had been to the mill and ground!”
—Oliver Wendell Holmes, Sr. (1809–1894)