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src/share/vm/runtime/sweeper.cpp@c6ff24ceec1c (annotated)

src/share/vm/runtime/sweeper.cpp

Thu, 10 Apr 2008 15:49:16 -0400

author

sbohne

date

Thu, 10 Apr 2008 15:49:16 -0400

changeset 528

c6ff24ceec1c

parent 435

a61af66fc99e

child 1376

8b46c4d82093

child 1424

148e5441d916

permissions

-rw-r--r--

6686407: Fix for 6666698 broke -XX:BiasedLockingStartupDelay=0
Summary: Stack allocated VM_EnableBiasedLocking op must be marked as such
Reviewed-by: xlu, acorn, never, dholmes

duke@435	1	/*
duke@435	2	* Copyright 1997-2005 Sun Microsystems, Inc. All Rights Reserved.
duke@435	3	* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
duke@435	4	*
duke@435	5	* This code is free software; you can redistribute it and/or modify it
duke@435	6	* under the terms of the GNU General Public License version 2 only, as
duke@435	7	* published by the Free Software Foundation.
duke@435	8	*
duke@435	9	* This code is distributed in the hope that it will be useful, but WITHOUT
duke@435	10	* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
duke@435	11	* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
duke@435	12	* version 2 for more details (a copy is included in the LICENSE file that
duke@435	13	* accompanied this code).
duke@435	14	*
duke@435	15	* You should have received a copy of the GNU General Public License version
duke@435	16	* 2 along with this work; if not, write to the Free Software Foundation,
duke@435	17	* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
duke@435	18	*
duke@435	19	* Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
duke@435	20	* CA 95054 USA or visit www.sun.com if you need additional information or
duke@435	21	* have any questions.
duke@435	22	*
duke@435	23	*/
duke@435	24
duke@435	25	# include "incls/_precompiled.incl"
duke@435	26	# include "incls/_sweeper.cpp.incl"
duke@435	27
duke@435	28	long NMethodSweeper::_traversals = 0; // No. of stack traversals performed
duke@435	29	CodeBlob* NMethodSweeper::_current = NULL; // Current nmethod
duke@435	30	int NMethodSweeper::_seen = 0 ; // No. of blobs we have currently processed in current pass of CodeCache
duke@435	31	int NMethodSweeper::_invocations = 0; // No. of invocations left until we are completed with this pass
duke@435	32
duke@435	33	jint NMethodSweeper::_locked_seen = 0;
duke@435	34	jint NMethodSweeper::_not_entrant_seen_on_stack = 0;
duke@435	35	bool NMethodSweeper::_rescan = false;
duke@435	36
duke@435	37	void NMethodSweeper::sweep() {
duke@435	38	assert(SafepointSynchronize::is_at_safepoint(), "must be executed at a safepoint");
duke@435	39	if (!MethodFlushing) return;
duke@435	40
duke@435	41	// No need to synchronize access, since this is always executed at a
duke@435	42	// safepoint. If we aren't in the middle of scan and a rescan
duke@435	43	// hasn't been requested then just return.
duke@435	44	if (_current == NULL && !_rescan) return;
duke@435	45
duke@435	46	// Make sure CompiledIC_lock in unlocked, since we might update some
duke@435	47	// inline caches. If it is, we just bail-out and try later.
duke@435	48	if (CompiledIC_lock->is_locked() || Patching_lock->is_locked()) return;
duke@435	49
duke@435	50	// Check for restart
duke@435	51	assert(CodeCache::find_blob_unsafe(_current) == _current, "Sweeper nmethod cached state invalid");
duke@435	52	if (_current == NULL) {
duke@435	53	_seen = 0;
duke@435	54	_invocations = NmethodSweepFraction;
duke@435	55	_current = CodeCache::first();
duke@435	56	_traversals += 1;
duke@435	57	if (PrintMethodFlushing) {
duke@435	58	tty->print_cr("### Sweep: stack traversal %d", _traversals);
duke@435	59	}
duke@435	60	Threads::nmethods_do();
duke@435	61
duke@435	62	// reset the flags since we started a scan from the beginning.
duke@435	63	_rescan = false;
duke@435	64	_locked_seen = 0;
duke@435	65	_not_entrant_seen_on_stack = 0;
duke@435	66	}
duke@435	67
duke@435	68	if (PrintMethodFlushing && Verbose) {
duke@435	69	tty->print_cr("### Sweep at %d out of %d. Invocations left: %d", _seen, CodeCache::nof_blobs(), _invocations);
duke@435	70	}
duke@435	71
duke@435	72	// We want to visit all nmethods after NmethodSweepFraction invocations.
duke@435	73	// If invocation is 1 we do the rest
duke@435	74	int todo = CodeCache::nof_blobs();
duke@435	75	if (_invocations != 1) {
duke@435	76	todo = (CodeCache::nof_blobs() - _seen) / _invocations;
duke@435	77	_invocations--;
duke@435	78	}
duke@435	79
duke@435	80	for(int i = 0; i < todo && _current != NULL; i++) {
duke@435	81	CodeBlob* next = CodeCache::next(_current); // Read next before we potentially delete current
duke@435	82	if (_current->is_nmethod()) {
duke@435	83	process_nmethod((nmethod *)_current);
duke@435	84	}
duke@435	85	_seen++;
duke@435	86	_current = next;
duke@435	87	}
duke@435	88	// Because we could stop on a codeBlob other than an nmethod we skip forward
duke@435	89	// to the next nmethod (if any). codeBlobs other than nmethods can be freed
duke@435	90	// async to us and make _current invalid while we sleep.
duke@435	91	while (_current != NULL && !_current->is_nmethod()) {
duke@435	92	_current = CodeCache::next(_current);
duke@435	93	}
duke@435	94
duke@435	95	if (_current == NULL && !_rescan && (_locked_seen || _not_entrant_seen_on_stack)) {
duke@435	96	// we've completed a scan without making progress but there were
duke@435	97	// nmethods we were unable to process either because they were
duke@435	98	// locked or were still on stack. We don't have to aggresively
duke@435	99	// clean them up so just stop scanning. We could scan once more
duke@435	100	// but that complicates the control logic and it's unlikely to
duke@435	101	// matter much.
duke@435	102	if (PrintMethodFlushing) {
duke@435	103	tty->print_cr("### Couldn't make progress on some nmethods so stopping sweep");
duke@435	104	}
duke@435	105	}
duke@435	106	}
duke@435	107
duke@435	108
duke@435	109	void NMethodSweeper::process_nmethod(nmethod *nm) {
duke@435	110	// Skip methods that are currently referenced by the VM
duke@435	111	if (nm->is_locked_by_vm()) {
duke@435	112	// But still remember to clean-up inline caches for alive nmethods
duke@435	113	if (nm->is_alive()) {
duke@435	114	// Clean-up all inline caches that points to zombie/non-reentrant methods
duke@435	115	nm->cleanup_inline_caches();
duke@435	116	} else {
duke@435	117	_locked_seen++;
duke@435	118	}
duke@435	119	return;
duke@435	120	}
duke@435	121
duke@435	122	if (nm->is_zombie()) {
duke@435	123	// If it is first time, we see nmethod then we mark it. Otherwise,
duke@435	124	// we reclame it. When we have seen a zombie method twice, we know that
duke@435	125	// there are no inline caches that referes to it.
duke@435	126	if (nm->is_marked_for_reclamation()) {
duke@435	127	assert(!nm->is_locked_by_vm(), "must not flush locked nmethods");
duke@435	128	nm->flush();
duke@435	129	} else {
duke@435	130	nm->mark_for_reclamation();
duke@435	131	_rescan = true;
duke@435	132	}
duke@435	133	} else if (nm->is_not_entrant()) {
duke@435	134	// If there is no current activations of this method on the
duke@435	135	// stack we can safely convert it to a zombie method
duke@435	136	if (nm->can_not_entrant_be_converted()) {
duke@435	137	nm->make_zombie();
duke@435	138	_rescan = true;
duke@435	139	} else {
duke@435	140	// Still alive, clean up its inline caches
duke@435	141	nm->cleanup_inline_caches();
duke@435	142	// we coudn't transition this nmethod so don't immediately
duke@435	143	// request a rescan. If this method stays on the stack for a
duke@435	144	// long time we don't want to keep rescanning at every safepoint.
duke@435	145	_not_entrant_seen_on_stack++;
duke@435	146	}
duke@435	147	} else if (nm->is_unloaded()) {
duke@435	148	// Unloaded code, just make it a zombie
duke@435	149	if (nm->is_osr_only_method()) {
duke@435	150	// No inline caches will ever point to osr methods, so we can just remove it
duke@435	151	nm->flush();
duke@435	152	} else {
duke@435	153	nm->make_zombie();
duke@435	154	_rescan = true;
duke@435	155	}
duke@435	156	} else {
duke@435	157	assert(nm->is_alive(), "should be alive");
duke@435	158	// Clean-up all inline caches that points to zombie/non-reentrant methods
duke@435	159	nm->cleanup_inline_caches();
duke@435	160	}
duke@435	161	}