Java Memory Management on HP-UX

page 132/8/2005
(c) Copyright Hewlett Packard Company, 2005
Java Memory Regions
• The JAVA threads are private mmap segments. The default size
for this mmap is 512KB(32bit), 1MB(64bit).
• JVM CodeCache (holds compiled JAVA methods) is a private
mmap segment. The default size is 32MB.
• The JAVA heap is a private mmap (Use -XheapInitialSizes to
determine sizes of different generations) segment. The three
regions in HotSpot JVM heap (new, old and permanent) are
allocated as three different mmap regions in 32bit mode in
1.3.1 or greater JVMs.
The JAVA heap is mapped MAP_NORESERVE (lazy swap). When
multiple processes are spawned, memory and swap have to be
estimated carefully, otherwise running processes may abort in
the middle of a run due to insufficient swap space, instead of
processes aborting at startup time.