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This commit is contained in:
Daniel D. Daugherty 2011-03-15 06:50:01 -07:00
commit 7c14db880f
5 changed files with 53 additions and 28 deletions
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34
hotspot/src/share/vm/code/nmethod.cpp
View file

@ -1183,14 +1183,17 @@ void nmethod::mark_as_seen_on_stack() {
set_stack_traversal_mark(NMethodSweeper::traversal_count());
}
// Tell if a non-entrant method can be converted to a zombie (i.e., there is no activations on the stack)
// Tell if a non-entrant method can be converted to a zombie (i.e.,
// there are no activations on the stack, not in use by the VM,
// and not in use by the ServiceThread)
bool nmethod::can_not_entrant_be_converted() {
assert(is_not_entrant(), "must be a non-entrant method");
// Since the nmethod sweeper only does partial sweep the sweeper's traversal
// count can be greater than the stack traversal count before it hits the
// nmethod for the second time.
return stack_traversal_mark()+1 < NMethodSweeper::traversal_count();
return stack_traversal_mark()+1 < NMethodSweeper::traversal_count() &&
!is_locked_by_vm();
}
void nmethod::inc_decompile_count() {
@ -1297,6 +1300,7 @@ void nmethod::log_state_change() const {
// Common functionality for both make_not_entrant and make_zombie
bool nmethod::make_not_entrant_or_zombie(unsigned int state) {
assert(state == zombie || state == not_entrant, "must be zombie or not_entrant");
assert(!is_zombie(), "should not already be a zombie");
// Make sure neither the nmethod nor the method is flushed in case of a safepoint in code below.
nmethodLocker nml(this);
@ -1304,11 +1308,6 @@ bool nmethod::make_not_entrant_or_zombie(unsigned int state) {
No_Safepoint_Verifier nsv;
{
// If the method is already zombie there is nothing to do
if (is_zombie()) {
return false;
}
// invalidate osr nmethod before acquiring the patching lock since
// they both acquire leaf locks and we don't want a deadlock.
// This logic is equivalent to the logic below for patching the
@ -1378,13 +1377,12 @@ bool nmethod::make_not_entrant_or_zombie(unsigned int state) {
flush_dependencies(NULL);
}
{
// zombie only - if a JVMTI agent has enabled the CompiledMethodUnload event
// and it hasn't already been reported for this nmethod then report it now.
// (the event may have been reported earilier if the GC marked it for unloading).
Pause_No_Safepoint_Verifier pnsv(&nsv);
post_compiled_method_unload();
}
// zombie only - if a JVMTI agent has enabled the CompiledMethodUnload
// event and it hasn't already been reported for this nmethod then
// report it now. The event may have been reported earilier if the GC
// marked it for unloading). JvmtiDeferredEventQueue support means
// we no longer go to a safepoint here.
post_compiled_method_unload();
#ifdef ASSERT
// It's no longer safe to access the oops section since zombie
@ -1569,7 +1567,7 @@ void nmethod::post_compiled_method_unload() {
if (_jmethod_id != NULL && JvmtiExport::should_post_compiled_method_unload()) {
assert(!unload_reported(), "already unloaded");
JvmtiDeferredEvent event =
JvmtiDeferredEvent::compiled_method_unload_event(
JvmtiDeferredEvent::compiled_method_unload_event(this,
_jmethod_id, insts_begin());
if (SafepointSynchronize::is_at_safepoint()) {
// Don't want to take the queueing lock. Add it as pending and
@ -2174,10 +2172,12 @@ nmethodLocker::nmethodLocker(address pc) {
lock_nmethod(_nm);
}
void nmethodLocker::lock_nmethod(nmethod* nm) {
// Only JvmtiDeferredEvent::compiled_method_unload_event()
// should pass zombie_ok == true.
void nmethodLocker::lock_nmethod(nmethod* nm, bool zombie_ok) {
if (nm == NULL) return;
Atomic::inc(&nm->_lock_count);
guarantee(!nm->is_zombie(), "cannot lock a zombie method");
guarantee(zombie_ok || !nm->is_zombie(), "cannot lock a zombie method");
}
void nmethodLocker::unlock_nmethod(nmethod* nm) {

21
hotspot/src/share/vm/code/nmethod.hpp
View file

@ -193,7 +193,10 @@ class nmethod : public CodeBlob {
NOT_PRODUCT(bool _has_debug_info; )
// Nmethod Flushing lock (if non-zero, then the nmethod is not removed)
// Nmethod Flushing lock. If non-zero, then the nmethod is not removed
// and is not made into a zombie. However, once the nmethod is made into
// a zombie, it will be locked one final time if CompiledMethodUnload
// event processing needs to be done.
jint _lock_count;
// not_entrant method removal. Each mark_sweep pass will update
@ -521,8 +524,9 @@ public:
void flush();
public:
// If returning true, it is unsafe to remove this nmethod even though it is a zombie
// nmethod, since the VM might have a reference to it. Should only be called from a safepoint.
// When true is returned, it is unsafe to remove this nmethod even if
// it is a zombie, since the VM or the ServiceThread might still be
// using it.
bool is_locked_by_vm() const { return _lock_count >0; }
// See comment at definition of _last_seen_on_stack
@ -688,13 +692,20 @@ public:
};
// Locks an nmethod so its code will not get removed, even if it is a zombie/not_entrant method
// Locks an nmethod so its code will not get removed and it will not
// be made into a zombie, even if it is a not_entrant method. After the
// nmethod becomes a zombie, if CompiledMethodUnload event processing
// needs to be done, then lock_nmethod() is used directly to keep the
// generated code from being reused too early.
class nmethodLocker : public StackObj {
nmethod* _nm;
public:
static void lock_nmethod(nmethod* nm); // note: nm can be NULL
// note: nm can be NULL
// Only JvmtiDeferredEvent::compiled_method_unload_event()
// should pass zombie_ok == true.
static void lock_nmethod(nmethod* nm, bool zombie_ok = false);
static void unlock_nmethod(nmethod* nm); // (ditto)
nmethodLocker(address pc); // derive nm from pc