author | trims |
Tue, 05 Apr 2011 14:12:31 -0700 | |
changeset 8921 | 14bfe81f2a9d |
parent 8672 | 26a427ab6f32 |
child 9138 | 35e4b04eadf4 |
permissions | -rw-r--r-- |
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/* |
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* Copyright (c) 1997, 2011, Oracle and/or its affiliates. All rights reserved. |
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
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* |
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* This code is free software; you can redistribute it and/or modify it |
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* under the terms of the GNU General Public License version 2 only, as |
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* published by the Free Software Foundation. |
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* |
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* This code is distributed in the hope that it will be useful, but WITHOUT |
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
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* version 2 for more details (a copy is included in the LICENSE file that |
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* accompanied this code). |
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* |
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* You should have received a copy of the GNU General Public License version |
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* 2 along with this work; if not, write to the Free Software Foundation, |
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
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* |
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
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* or visit www.oracle.com if you need additional information or have any |
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* questions. |
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* |
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*/ |
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||
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#include "precompiled.hpp" |
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#include "code/codeCache.hpp" |
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#include "code/nmethod.hpp" |
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#include "compiler/compileBroker.hpp" |
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#include "memory/resourceArea.hpp" |
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#include "oops/methodOop.hpp" |
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#include "runtime/atomic.hpp" |
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#include "runtime/compilationPolicy.hpp" |
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#include "runtime/mutexLocker.hpp" |
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#include "runtime/os.hpp" |
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#include "runtime/sweeper.hpp" |
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#include "runtime/vm_operations.hpp" |
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#include "utilities/events.hpp" |
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#include "utilities/xmlstream.hpp" |
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long NMethodSweeper::_traversals = 0; // No. of stack traversals performed |
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nmethod* NMethodSweeper::_current = NULL; // Current nmethod |
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int NMethodSweeper::_seen = 0 ; // No. of nmethods we have currently processed in current pass of CodeCache |
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volatile int NMethodSweeper::_invocations = 0; // No. of invocations left until we are completed with this pass |
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volatile int NMethodSweeper::_sweep_started = 0; // Whether a sweep is in progress. |
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jint NMethodSweeper::_locked_seen = 0; |
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jint NMethodSweeper::_not_entrant_seen_on_stack = 0; |
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bool NMethodSweeper::_rescan = false; |
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bool NMethodSweeper::_do_sweep = false; |
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bool NMethodSweeper::_was_full = false; |
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jint NMethodSweeper::_advise_to_sweep = 0; |
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jlong NMethodSweeper::_last_was_full = 0; |
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uint NMethodSweeper::_highest_marked = 0; |
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long NMethodSweeper::_was_full_traversal = 0; |
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class MarkActivationClosure: public CodeBlobClosure { |
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public: |
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virtual void do_code_blob(CodeBlob* cb) { |
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// If we see an activation belonging to a non_entrant nmethod, we mark it. |
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if (cb->is_nmethod() && ((nmethod*)cb)->is_not_entrant()) { |
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((nmethod*)cb)->mark_as_seen_on_stack(); |
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} |
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} |
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}; |
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static MarkActivationClosure mark_activation_closure; |
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void NMethodSweeper::scan_stacks() { |
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assert(SafepointSynchronize::is_at_safepoint(), "must be executed at a safepoint"); |
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if (!MethodFlushing) return; |
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_do_sweep = true; |
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// No need to synchronize access, since this is always executed at a |
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// safepoint. If we aren't in the middle of scan and a rescan |
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// hasn't been requested then just return. If UseCodeCacheFlushing is on and |
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// code cache flushing is in progress, don't skip sweeping to help make progress |
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// clearing space in the code cache. |
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if ((_current == NULL && !_rescan) && !(UseCodeCacheFlushing && !CompileBroker::should_compile_new_jobs())) { |
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_do_sweep = false; |
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return; |
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} |
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// Make sure CompiledIC_lock in unlocked, since we might update some |
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// inline caches. If it is, we just bail-out and try later. |
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if (CompiledIC_lock->is_locked() || Patching_lock->is_locked()) return; |
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// Check for restart |
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assert(CodeCache::find_blob_unsafe(_current) == _current, "Sweeper nmethod cached state invalid"); |
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if (_current == NULL) { |
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_seen = 0; |
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_invocations = NmethodSweepFraction; |
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_current = CodeCache::first_nmethod(); |
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_traversals += 1; |
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if (PrintMethodFlushing) { |
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tty->print_cr("### Sweep: stack traversal %d", _traversals); |
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} |
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Threads::nmethods_do(&mark_activation_closure); |
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// reset the flags since we started a scan from the beginning. |
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_rescan = false; |
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_locked_seen = 0; |
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_not_entrant_seen_on_stack = 0; |
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} |
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if (UseCodeCacheFlushing) { |
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if (!CodeCache::needs_flushing()) { |
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// scan_stacks() runs during a safepoint, no race with setters |
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_advise_to_sweep = 0; |
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} |
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if (was_full()) { |
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// There was some progress so attempt to restart the compiler |
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jlong now = os::javaTimeMillis(); |
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jlong max_interval = (jlong)MinCodeCacheFlushingInterval * (jlong)1000; |
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jlong curr_interval = now - _last_was_full; |
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if ((!CodeCache::needs_flushing()) && (curr_interval > max_interval)) { |
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CompileBroker::set_should_compile_new_jobs(CompileBroker::run_compilation); |
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set_was_full(false); |
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// Update the _last_was_full time so we can tell how fast the |
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// code cache is filling up |
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_last_was_full = os::javaTimeMillis(); |
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log_sweep("restart_compiler"); |
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} |
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} |
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} |
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} |
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void NMethodSweeper::possibly_sweep() { |
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assert(JavaThread::current()->thread_state() == _thread_in_vm, "must run in vm mode"); |
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if ((!MethodFlushing) || (!_do_sweep)) return; |
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if (_invocations > 0) { |
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// Only one thread at a time will sweep |
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jint old = Atomic::cmpxchg( 1, &_sweep_started, 0 ); |
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if (old != 0) { |
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return; |
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} |
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if (_invocations > 0) { |
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sweep_code_cache(); |
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_invocations--; |
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} |
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_sweep_started = 0; |
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} |
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} |
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void NMethodSweeper::sweep_code_cache() { |
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#ifdef ASSERT |
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jlong sweep_start; |
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if (PrintMethodFlushing) { |
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sweep_start = os::javaTimeMillis(); |
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} |
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#endif |
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if (PrintMethodFlushing && Verbose) { |
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tty->print_cr("### Sweep at %d out of %d. Invocations left: %d", _seen, CodeCache::nof_nmethods(), _invocations); |
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} |
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// We want to visit all nmethods after NmethodSweepFraction |
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// invocations so divide the remaining number of nmethods by the |
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// remaining number of invocations. This is only an estimate since |
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// the number of nmethods changes during the sweep so the final |
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// stage must iterate until it there are no more nmethods. |
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int todo = (CodeCache::nof_nmethods() - _seen) / _invocations; |
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assert(!SafepointSynchronize::is_at_safepoint(), "should not be in safepoint when we get here"); |
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assert(!CodeCache_lock->owned_by_self(), "just checking"); |
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{ |
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MutexLockerEx mu(CodeCache_lock, Mutex::_no_safepoint_check_flag); |
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// The last invocation iterates until there are no more nmethods |
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for (int i = 0; (i < todo || _invocations == 1) && _current != NULL; i++) { |
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// Since we will give up the CodeCache_lock, always skip ahead |
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// to the next nmethod. Other blobs can be deleted by other |
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// threads but nmethods are only reclaimed by the sweeper. |
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nmethod* next = CodeCache::next_nmethod(_current); |
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// Now ready to process nmethod and give up CodeCache_lock |
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{ |
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MutexUnlockerEx mu(CodeCache_lock, Mutex::_no_safepoint_check_flag); |
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process_nmethod(_current); |
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} |
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_seen++; |
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_current = next; |
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} |
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} |
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assert(_invocations > 1 || _current == NULL, "must have scanned the whole cache"); |
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if (_current == NULL && !_rescan && (_locked_seen || _not_entrant_seen_on_stack)) { |
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// we've completed a scan without making progress but there were |
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// nmethods we were unable to process either because they were |
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// locked or were still on stack. We don't have to aggresively |
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// clean them up so just stop scanning. We could scan once more |
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// but that complicates the control logic and it's unlikely to |
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198 |
// matter much. |
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199 |
if (PrintMethodFlushing) { |
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200 |
tty->print_cr("### Couldn't make progress on some nmethods so stopping sweep"); |
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201 |
} |
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202 |
} |
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203 |
|
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204 |
#ifdef ASSERT |
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205 |
if(PrintMethodFlushing) { |
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206 |
jlong sweep_end = os::javaTimeMillis(); |
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207 |
tty->print_cr("### sweeper: sweep time(%d): " INT64_FORMAT, _invocations, sweep_end - sweep_start); |
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208 |
} |
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209 |
#endif |
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210 |
|
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211 |
if (_invocations == 1) { |
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log_sweep("finished"); |
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213 |
} |
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214 |
} |
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215 |
|
1 | 216 |
|
217 |
void NMethodSweeper::process_nmethod(nmethod *nm) { |
|
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assert(!CodeCache_lock->owned_by_self(), "just checking"); |
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219 |
|
1 | 220 |
// Skip methods that are currently referenced by the VM |
221 |
if (nm->is_locked_by_vm()) { |
|
222 |
// But still remember to clean-up inline caches for alive nmethods |
|
223 |
if (nm->is_alive()) { |
|
224 |
// Clean-up all inline caches that points to zombie/non-reentrant methods |
|
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225 |
MutexLocker cl(CompiledIC_lock); |
1 | 226 |
nm->cleanup_inline_caches(); |
227 |
} else { |
|
228 |
_locked_seen++; |
|
229 |
} |
|
230 |
return; |
|
231 |
} |
|
232 |
||
233 |
if (nm->is_zombie()) { |
|
234 |
// If it is first time, we see nmethod then we mark it. Otherwise, |
|
235 |
// we reclame it. When we have seen a zombie method twice, we know that |
|
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236 |
// there are no inline caches that refer to it. |
1 | 237 |
if (nm->is_marked_for_reclamation()) { |
238 |
assert(!nm->is_locked_by_vm(), "must not flush locked nmethods"); |
|
3696 | 239 |
if (PrintMethodFlushing && Verbose) { |
4750 | 240 |
tty->print_cr("### Nmethod %3d/" PTR_FORMAT " (marked for reclamation) being flushed", nm->compile_id(), nm); |
3696 | 241 |
} |
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242 |
MutexLockerEx mu(CodeCache_lock, Mutex::_no_safepoint_check_flag); |
1 | 243 |
nm->flush(); |
244 |
} else { |
|
3696 | 245 |
if (PrintMethodFlushing && Verbose) { |
4750 | 246 |
tty->print_cr("### Nmethod %3d/" PTR_FORMAT " (zombie) being marked for reclamation", nm->compile_id(), nm); |
3696 | 247 |
} |
1 | 248 |
nm->mark_for_reclamation(); |
249 |
_rescan = true; |
|
250 |
} |
|
251 |
} else if (nm->is_not_entrant()) { |
|
252 |
// If there is no current activations of this method on the |
|
253 |
// stack we can safely convert it to a zombie method |
|
254 |
if (nm->can_not_entrant_be_converted()) { |
|
3696 | 255 |
if (PrintMethodFlushing && Verbose) { |
4750 | 256 |
tty->print_cr("### Nmethod %3d/" PTR_FORMAT " (not entrant) being made zombie", nm->compile_id(), nm); |
3696 | 257 |
} |
1 | 258 |
nm->make_zombie(); |
259 |
_rescan = true; |
|
260 |
} else { |
|
261 |
// Still alive, clean up its inline caches |
|
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262 |
MutexLocker cl(CompiledIC_lock); |
1 | 263 |
nm->cleanup_inline_caches(); |
264 |
// we coudn't transition this nmethod so don't immediately |
|
265 |
// request a rescan. If this method stays on the stack for a |
|
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266 |
// long time we don't want to keep rescanning the code cache. |
1 | 267 |
_not_entrant_seen_on_stack++; |
268 |
} |
|
269 |
} else if (nm->is_unloaded()) { |
|
270 |
// Unloaded code, just make it a zombie |
|
3696 | 271 |
if (PrintMethodFlushing && Verbose) |
4750 | 272 |
tty->print_cr("### Nmethod %3d/" PTR_FORMAT " (unloaded) being made zombie", nm->compile_id(), nm); |
3696 | 273 |
if (nm->is_osr_method()) { |
1 | 274 |
// No inline caches will ever point to osr methods, so we can just remove it |
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275 |
MutexLockerEx mu(CodeCache_lock, Mutex::_no_safepoint_check_flag); |
1 | 276 |
nm->flush(); |
277 |
} else { |
|
278 |
nm->make_zombie(); |
|
279 |
_rescan = true; |
|
280 |
} |
|
281 |
} else { |
|
282 |
assert(nm->is_alive(), "should be alive"); |
|
4750 | 283 |
|
284 |
if (UseCodeCacheFlushing) { |
|
285 |
if ((nm->method()->code() != nm) && !(nm->is_locked_by_vm()) && !(nm->is_osr_method()) && |
|
286 |
(_traversals > _was_full_traversal+2) && (((uint)nm->compile_id()) < _highest_marked) && |
|
287 |
CodeCache::needs_flushing()) { |
|
288 |
// This method has not been called since the forced cleanup happened |
|
289 |
nm->make_not_entrant(); |
|
290 |
} |
|
291 |
} |
|
292 |
||
1 | 293 |
// Clean-up all inline caches that points to zombie/non-reentrant methods |
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294 |
MutexLocker cl(CompiledIC_lock); |
1 | 295 |
nm->cleanup_inline_caches(); |
296 |
} |
|
297 |
} |
|
4750 | 298 |
|
299 |
// Code cache unloading: when compilers notice the code cache is getting full, |
|
300 |
// they will call a vm op that comes here. This code attempts to speculatively |
|
301 |
// unload the oldest half of the nmethods (based on the compile job id) by |
|
302 |
// saving the old code in a list in the CodeCache. Then |
|
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303 |
// execution resumes. If a method so marked is not called by the second sweeper |
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304 |
// stack traversal after the current one, the nmethod will be marked non-entrant and |
4750 | 305 |
// got rid of by normal sweeping. If the method is called, the methodOop's |
306 |
// _code field is restored and the methodOop/nmethod |
|
307 |
// go back to their normal state. |
|
308 |
void NMethodSweeper::handle_full_code_cache(bool is_full) { |
|
309 |
// Only the first one to notice can advise us to start early cleaning |
|
310 |
if (!is_full){ |
|
311 |
jint old = Atomic::cmpxchg( 1, &_advise_to_sweep, 0 ); |
|
312 |
if (old != 0) { |
|
313 |
return; |
|
314 |
} |
|
315 |
} |
|
316 |
||
317 |
if (is_full) { |
|
318 |
// Since code cache is full, immediately stop new compiles |
|
319 |
bool did_set = CompileBroker::set_should_compile_new_jobs(CompileBroker::stop_compilation); |
|
320 |
if (!did_set) { |
|
321 |
// only the first to notice can start the cleaning, |
|
322 |
// others will go back and block |
|
323 |
return; |
|
324 |
} |
|
325 |
set_was_full(true); |
|
326 |
||
327 |
// If we run out within MinCodeCacheFlushingInterval of the last unload time, give up |
|
328 |
jlong now = os::javaTimeMillis(); |
|
329 |
jlong max_interval = (jlong)MinCodeCacheFlushingInterval * (jlong)1000; |
|
330 |
jlong curr_interval = now - _last_was_full; |
|
331 |
if (curr_interval < max_interval) { |
|
332 |
_rescan = true; |
|
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333 |
log_sweep("disable_compiler", "flushing_interval='" UINT64_FORMAT "'", |
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|
334 |
curr_interval/1000); |
4750 | 335 |
return; |
336 |
} |
|
337 |
} |
|
338 |
||
339 |
VM_HandleFullCodeCache op(is_full); |
|
340 |
VMThread::execute(&op); |
|
341 |
||
342 |
// rescan again as soon as possible |
|
343 |
_rescan = true; |
|
344 |
} |
|
345 |
||
346 |
void NMethodSweeper::speculative_disconnect_nmethods(bool is_full) { |
|
347 |
// If there was a race in detecting full code cache, only run |
|
348 |
// one vm op for it or keep the compiler shut off |
|
349 |
||
350 |
debug_only(jlong start = os::javaTimeMillis();) |
|
351 |
||
352 |
if ((!was_full()) && (is_full)) { |
|
353 |
if (!CodeCache::needs_flushing()) { |
|
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|
354 |
log_sweep("restart_compiler"); |
4750 | 355 |
CompileBroker::set_should_compile_new_jobs(CompileBroker::run_compilation); |
356 |
return; |
|
357 |
} |
|
358 |
} |
|
359 |
||
360 |
// Traverse the code cache trying to dump the oldest nmethods |
|
361 |
uint curr_max_comp_id = CompileBroker::get_compilation_id(); |
|
362 |
uint flush_target = ((curr_max_comp_id - _highest_marked) >> 1) + _highest_marked; |
|
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|
363 |
log_sweep("start_cleaning"); |
4750 | 364 |
|
365 |
nmethod* nm = CodeCache::alive_nmethod(CodeCache::first()); |
|
366 |
jint disconnected = 0; |
|
367 |
jint made_not_entrant = 0; |
|
368 |
while ((nm != NULL)){ |
|
369 |
uint curr_comp_id = nm->compile_id(); |
|
370 |
||
371 |
// OSR methods cannot be flushed like this. Also, don't flush native methods |
|
372 |
// since they are part of the JDK in most cases |
|
373 |
if (nm->is_in_use() && (!nm->is_osr_method()) && (!nm->is_locked_by_vm()) && |
|
374 |
(!nm->is_native_method()) && ((curr_comp_id < flush_target))) { |
|
375 |
||
376 |
if ((nm->method()->code() == nm)) { |
|
377 |
// This method has not been previously considered for |
|
378 |
// unloading or it was restored already |
|
379 |
CodeCache::speculatively_disconnect(nm); |
|
380 |
disconnected++; |
|
381 |
} else if (nm->is_speculatively_disconnected()) { |
|
382 |
// This method was previously considered for preemptive unloading and was not called since then |
|
6453 | 383 |
CompilationPolicy::policy()->delay_compilation(nm->method()); |
4750 | 384 |
nm->make_not_entrant(); |
385 |
made_not_entrant++; |
|
386 |
} |
|
387 |
||
388 |
if (curr_comp_id > _highest_marked) { |
|
389 |
_highest_marked = curr_comp_id; |
|
390 |
} |
|
391 |
} |
|
392 |
nm = CodeCache::alive_nmethod(CodeCache::next(nm)); |
|
393 |
} |
|
394 |
||
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|
395 |
log_sweep("stop_cleaning", |
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|
396 |
"disconnected='" UINT32_FORMAT "' made_not_entrant='" UINT32_FORMAT "'", |
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|
397 |
disconnected, made_not_entrant); |
4750 | 398 |
|
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|
399 |
// Shut off compiler. Sweeper will start over with a new stack scan and |
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|
400 |
// traversal cycle and turn it back on if it clears enough space. |
4750 | 401 |
if (was_full()) { |
402 |
_last_was_full = os::javaTimeMillis(); |
|
403 |
CompileBroker::set_should_compile_new_jobs(CompileBroker::stop_compilation); |
|
404 |
} |
|
405 |
||
406 |
// After two more traversals the sweeper will get rid of unrestored nmethods |
|
407 |
_was_full_traversal = _traversals; |
|
408 |
#ifdef ASSERT |
|
409 |
jlong end = os::javaTimeMillis(); |
|
410 |
if(PrintMethodFlushing && Verbose) { |
|
411 |
tty->print_cr("### sweeper: unload time: " INT64_FORMAT, end-start); |
|
412 |
} |
|
413 |
#endif |
|
414 |
} |
|
5924
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|
415 |
|
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|
416 |
|
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|
417 |
// Print out some state information about the current sweep and the |
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|
418 |
// state of the code cache if it's requested. |
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|
419 |
void NMethodSweeper::log_sweep(const char* msg, const char* format, ...) { |
dc9d04930c82
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|
420 |
if (PrintMethodFlushing) { |
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|
421 |
ttyLocker ttyl; |
dc9d04930c82
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|
422 |
tty->print("### sweeper: %s ", msg); |
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|
423 |
if (format != NULL) { |
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|
424 |
va_list ap; |
dc9d04930c82
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|
425 |
va_start(ap, format); |
dc9d04930c82
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|
426 |
tty->vprint(format, ap); |
dc9d04930c82
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|
427 |
va_end(ap); |
dc9d04930c82
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|
428 |
} |
8672
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|
429 |
CodeCache::log_state(tty); tty->cr(); |
5924
dc9d04930c82
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|
430 |
} |
dc9d04930c82
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|
431 |
|
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|
432 |
if (LogCompilation && (xtty != NULL)) { |
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|
433 |
ttyLocker ttyl; |
5926 | 434 |
xtty->begin_elem("sweeper state='%s' traversals='" INTX_FORMAT "' ", msg, (intx)traversal_count()); |
5924
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|
435 |
if (format != NULL) { |
dc9d04930c82
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|
436 |
va_list ap; |
dc9d04930c82
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|
437 |
va_start(ap, format); |
dc9d04930c82
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|
438 |
xtty->vprint(format, ap); |
dc9d04930c82
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|
439 |
va_end(ap); |
dc9d04930c82
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|
440 |
} |
8672
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kvn
parents:
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changeset
|
441 |
CodeCache::log_state(xtty); |
5924
dc9d04930c82
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|
442 |
xtty->stamp(); |
dc9d04930c82
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|
443 |
xtty->end_elem(); |
dc9d04930c82
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changeset
|
444 |
} |
dc9d04930c82
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|
445 |
} |