Sill question

[Krystal Mok]

Hi Kirk,

Does this stack trace help you?

#0  os::attempt_reserve_memory_at (bytes=2149580800,
requested_addr=0x77fe00000 <Address 0x77fe00000 out of bounds>)
    at /media/Data/build/hotspot-comp/hotspot/src/os/linux/vm/os_linux.cpp:3185
#1  0x00007ffff6de3ca0 in ReservedSpace::ReservedSpace
(this=0x7ffff7fd69d0, prefix_size=<value optimized out>,
prefix_align=65536,
    suffix_size=<value optimized out>, suffix_align=<value optimized out>,
    requested_address=0x77fe00000 <Address 0x77fe00000 out of bounds>,
noaccess_prefix=0)
    at /media/Data/build/hotspot-comp/hotspot/src/share/vm/runtime/virtualspace.cpp:205
#2  0x00007ffff6de40a0 in ReservedHeapSpace::ReservedHeapSpace
(this=0x7ffff7fd69d0, prefix_size=85983232, prefix_align=2063597568,
    suffix_size=2063597568, suffix_align=65536,
requested_address=0x77fe00000 <Address 0x77fe00000 out of bounds>)
    at /media/Data/build/hotspot-comp/hotspot/src/share/vm/runtime/virtualspace.cpp:506
#3  0x00007ffff6bfea1a in ParallelScavengeHeap::initialize (this=0x61de68)
    at /media/Data/build/hotspot-comp/hotspot/src/share/vm/gc_implementation/parallelScavenge/parallelScavengeHeap.cpp:141
#4  0x00007ffff6daf0a6 in Universe::initialize_heap () at
/media/Data/build/hotspot-comp/hotspot/src/share/vm/memory/universe.cpp:925
#5  0x00007ffff6daf568 in universe_init () at
/media/Data/build/hotspot-comp/hotspot/src/share/vm/memory/universe.cpp:782
#6  0x00007ffff68a16ea in init_globals () at
/media/Data/build/hotspot-comp/hotspot/src/share/vm/runtime/init.cpp:100
#7  0x00007ffff6d8e582 in Threads::create_vm (args=<value optimized
out>, canTryAgain=0x7ffff7fd6daf)
    at /media/Data/build/hotspot-comp/hotspot/src/share/vm/runtime/thread.cpp:3220
#8  0x00007ffff691ee0e in JNI_CreateJavaVM (vm=0x7ffff7fd6e78,
penv=0x7ffff7fd6e70, args=0x7ffff7fd6e50)
    at /media/Data/build/hotspot-comp/hotspot/src/share/vm/prims/jni.cpp:5131
#9  0x00007ffff79ac1b7 in JavaMain () from
/media/Data/build/testjdk7u1/bin/../jre/lib/amd64/jli/libjli.so
#10 0x00007ffff7bc6971 in start_thread (arg=<value optimized out>) at
pthread_create.c:304
#11 0x00007ffff7507f3d in clone () at
../sysdeps/unix/sysv/linux/x86_64/clone.S:112
#12 0x0000000000000000 in ?? ()

(BTW this stack trace is from a build of somewhat old version of JDK7,
not from the latest hotspot-comp)

The place to look for is the Universe::heap()->initialize() call in
Universe::initialize_heap(), that's the high-level entry point of
where the GC heap is reserved. The code in init_globals() in
hotspot/src/share/vm/runtime/init.cpp and Threads::create_vm() in
hotspot/src/share/vm/runtime/thread.cpp should give you what you need.

- Kris

On Wed, Dec 19, 2012 at 4:38 AM, Kirk Pepperdine <kirk at kodewerk.com> wrote:
> Hi,
>
> I have a silly question that I'd like to ask here before digging into the code. When in the startup sequence of the JVM does Java Heap get reserved/allocated?
>
> TIA,
> Kirk