jint Universe::initialize_heap() {
if (UseParallelGC) {
#ifndef SERIALGC
Universe::_collectedHeap = new ParallelScavengeHeap();
#else // SERIALGC
fatal("UseParallelGC not supported in java kernel vm.");
#endif // SERIALGC
} else if (UseG1GC) {
#ifndef SERIALGC
G1CollectorPolicy* g1p = new G1CollectorPolicy_BestRegionsFirst();
G1CollectedHeap* g1h = new G1CollectedHeap(g1p);
Universe::_collectedHeap = g1h;
#else // SERIALGC
fatal("UseG1GC not supported in java kernel vm.");
#endif // SERIALGC
} else {
GenCollectorPolicy *gc_policy;
if (UseSerialGC) {
gc_policy = new MarkSweepPolicy();
} else if (UseConcMarkSweepGC) {
#ifndef SERIALGC
if (UseAdaptiveSizePolicy) {
gc_policy = new ASConcurrentMarkSweepPolicy();
} else {
gc_policy = new ConcurrentMarkSweepPolicy();
}
#else // SERIALGC
fatal("UseConcMarkSweepGC not supported in java kernel vm.");
#endif // SERIALGC
} else { // default old generation
gc_policy = new MarkSweepPolicy();
}
Universe::_collectedHeap = new GenCollectedHeap(gc_policy);
}
jint status = Universe::heap()->initialize();
if (status != JNI_OK) {
return status;
}
#ifdef _LP64
if (UseCompressedOops) {
// Subtract a page because something can get allocated at heap base.
// This also makes implicit null checking work, because the
// memory+1 page below heap_base needs to cause a signal.
// See needs_explicit_null_check.
// Only set the heap base for compressed oops because it indicates
// compressed oops for pstack code.
if (PrintCompressedOopsMode) {
tty->cr();
tty->print("heap address: "PTR_FORMAT, Universe::heap()->base());
}
if ((uint64_t)Universe::heap()->reserved_region().end() > OopEncodingHeapMax) {
// Can't reserve heap below 32Gb.
Universe::set_narrow_oop_base(Universe::heap()->base() - os::vm_page_size());
Universe::set_narrow_oop_shift(LogMinObjAlignmentInBytes);
if (PrintCompressedOopsMode) {
tty->print(", Compressed Oops with base: "PTR_FORMAT, Universe::narrow_oop_base());
}
} else {
Universe::set_narrow_oop_base(0);
if (PrintCompressedOopsMode) {
tty->print(", zero based Compressed Oops");
}
#ifdef _WIN64
if (!Universe::narrow_oop_use_implicit_null_checks()) {
// Don't need guard page for implicit checks in indexed addressing
// mode with zero based Compressed Oops.
Universe::set_narrow_oop_use_implicit_null_checks(true);
}
#endif // _WIN64
if((uint64_t)Universe::heap()->reserved_region().end() > NarrowOopHeapMax) {
// Can't reserve heap below 4Gb.
Universe::set_narrow_oop_shift(LogMinObjAlignmentInBytes);
} else {
Universe::set_narrow_oop_shift(0);
if (PrintCompressedOopsMode) {
tty->print(", 32-bits Oops");
}
}
}
if (PrintCompressedOopsMode) {
tty->cr();
tty->cr();
}
}
assert(Universe::narrow_oop_base() == (Universe::heap()->base() - os::vm_page_size()) ||
Universe::narrow_oop_base() == NULL, "invalid value");
assert(Universe::narrow_oop_shift() == LogMinObjAlignmentInBytes ||
Universe::narrow_oop_shift() == 0, "invalid value");
#endif
// We will never reach the CATCH below since Exceptions::_throw will cause
// the VM to exit if an exception is thrown during initialization
if (UseTLAB) {
assert(Universe::heap()->supports_tlab_allocation(),
"Should support thread-local allocation buffers");
ThreadLocalAllocBuffer::startup_initialization();
}
return JNI_OK;
}
jvm 内存
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转载自cooldatabase.iteye.com/blog/547709
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