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6965184: possible races in make_not_entrant_or_zombie
Reviewed-by: kvn
This commit is contained in:
Tom Rodriguez
parent
ae3ddc1514
commit
7533d0caf7
22 changed files with 226 additions and 740 deletions
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@ -1,5 +1,5 @@
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/*
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* Copyright (c) 1997, 2009, Oracle and/or its affiliates. All rights reserved.
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* Copyright (c) 1997, 2010, 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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@ -27,14 +27,15 @@
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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 blobs we have currently processed in current pass of CodeCache
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int NMethodSweeper::_invocations = 0; // No. of invocations left until we are completed with this pass
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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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jint NMethodSweeper::_sweep_started = 0;
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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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@ -108,23 +109,14 @@ void NMethodSweeper::scan_stacks() {
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// code cache is filling up
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_last_was_full = os::javaTimeMillis();
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if (PrintMethodFlushing) {
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tty->print_cr("### sweeper: Live blobs:" UINT32_FORMAT "/Free code cache:" SIZE_FORMAT " bytes, restarting compiler",
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CodeCache::nof_blobs(), CodeCache::unallocated_capacity());
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}
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if (LogCompilation && (xtty != NULL)) {
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ttyLocker ttyl;
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xtty->begin_elem("restart_compiler live_blobs='" UINT32_FORMAT "' free_code_cache='" SIZE_FORMAT "'",
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CodeCache::nof_blobs(), CodeCache::unallocated_capacity());
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xtty->stamp();
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xtty->end_elem();
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}
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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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@ -133,32 +125,31 @@ void NMethodSweeper::possibly_sweep() {
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if (old != 0) {
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return;
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}
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sweep_code_cache();
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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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_sweep_started = 0;
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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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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_blobs(), _invocations);
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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 invocations.
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// If invocation is 1 we do the rest
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int todo = CodeCache::nof_blobs();
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if (_invocations > 1) {
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todo = (CodeCache::nof_blobs() - _seen) / _invocations;
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}
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// Compilers may check to sweep more often than stack scans happen,
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// don't keep trying once it is all scanned
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_invocations--;
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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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@ -166,11 +157,12 @@ void NMethodSweeper::sweep_code_cache() {
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{
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MutexLockerEx mu(CodeCache_lock, Mutex::_no_safepoint_check_flag);
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for(int i = 0; i < todo && _current != NULL; i++) {
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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 to an nmethod.
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// Other blobs can be deleted by other threads
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// Read next before we potentially delete current
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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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@ -183,6 +175,8 @@ void NMethodSweeper::sweep_code_cache() {
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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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@ -201,6 +195,10 @@ void NMethodSweeper::sweep_code_cache() {
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tty->print_cr("### sweeper: sweep time(%d): " INT64_FORMAT, _invocations, sweep_end - sweep_start);
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}
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#endif
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if (_invocations == 1) {
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log_sweep("finished");
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}
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}
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@ -223,7 +221,7 @@ void NMethodSweeper::process_nmethod(nmethod *nm) {
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if (nm->is_zombie()) {
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// If it is first time, we see nmethod then we mark it. Otherwise,
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// we reclame it. When we have seen a zombie method twice, we know that
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// there are no inline caches that referes to it.
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// there are no inline caches that refer to it.
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if (nm->is_marked_for_reclamation()) {
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assert(!nm->is_locked_by_vm(), "must not flush locked nmethods");
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if (PrintMethodFlushing && Verbose) {
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@ -320,16 +318,8 @@ void NMethodSweeper::handle_full_code_cache(bool is_full) {
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jlong curr_interval = now - _last_was_full;
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if (curr_interval < max_interval) {
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_rescan = true;
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if (PrintMethodFlushing) {
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tty->print_cr("### handle full too often, turning off compiler");
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}
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if (LogCompilation && (xtty != NULL)) {
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ttyLocker ttyl;
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xtty->begin_elem("disable_compiler flushing_interval='" UINT64_FORMAT "' live_blobs='" UINT32_FORMAT "' free_code_cache='" SIZE_FORMAT "'",
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curr_interval/1000, CodeCache::nof_blobs(), CodeCache::unallocated_capacity());
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xtty->stamp();
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xtty->end_elem();
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}
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log_sweep("disable_compiler", "flushing_interval='" UINT64_FORMAT "'",
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curr_interval/1000);
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return;
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}
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}
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@ -349,17 +339,7 @@ void NMethodSweeper::speculative_disconnect_nmethods(bool is_full) {
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if ((!was_full()) && (is_full)) {
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if (!CodeCache::needs_flushing()) {
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if (PrintMethodFlushing) {
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tty->print_cr("### sweeper: Live blobs:" UINT32_FORMAT "/Free code cache:" SIZE_FORMAT " bytes, restarting compiler",
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CodeCache::nof_blobs(), CodeCache::unallocated_capacity());
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}
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if (LogCompilation && (xtty != NULL)) {
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ttyLocker ttyl;
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xtty->begin_elem("restart_compiler live_blobs='" UINT32_FORMAT "' free_code_cache='" SIZE_FORMAT "'",
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CodeCache::nof_blobs(), CodeCache::unallocated_capacity());
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xtty->stamp();
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xtty->end_elem();
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}
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log_sweep("restart_compiler");
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CompileBroker::set_should_compile_new_jobs(CompileBroker::run_compilation);
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return;
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}
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@ -368,17 +348,7 @@ void NMethodSweeper::speculative_disconnect_nmethods(bool is_full) {
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// Traverse the code cache trying to dump the oldest nmethods
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uint curr_max_comp_id = CompileBroker::get_compilation_id();
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uint flush_target = ((curr_max_comp_id - _highest_marked) >> 1) + _highest_marked;
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if (PrintMethodFlushing && Verbose) {
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tty->print_cr("### Cleaning code cache: Live blobs:" UINT32_FORMAT "/Free code cache:" SIZE_FORMAT " bytes",
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CodeCache::nof_blobs(), CodeCache::unallocated_capacity());
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}
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if (LogCompilation && (xtty != NULL)) {
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ttyLocker ttyl;
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xtty->begin_elem("start_cleaning_code_cache live_blobs='" UINT32_FORMAT "' free_code_cache='" SIZE_FORMAT "'",
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CodeCache::nof_blobs(), CodeCache::unallocated_capacity());
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xtty->stamp();
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xtty->end_elem();
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}
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log_sweep("start_cleaning");
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nmethod* nm = CodeCache::alive_nmethod(CodeCache::first());
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jint disconnected = 0;
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@ -411,13 +381,9 @@ void NMethodSweeper::speculative_disconnect_nmethods(bool is_full) {
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nm = CodeCache::alive_nmethod(CodeCache::next(nm));
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}
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if (LogCompilation && (xtty != NULL)) {
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ttyLocker ttyl;
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xtty->begin_elem("stop_cleaning_code_cache disconnected='" UINT32_FORMAT "' made_not_entrant='" UINT32_FORMAT "' live_blobs='" UINT32_FORMAT "' free_code_cache='" SIZE_FORMAT "'",
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disconnected, made_not_entrant, CodeCache::nof_blobs(), CodeCache::unallocated_capacity());
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xtty->stamp();
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xtty->end_elem();
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}
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log_sweep("stop_cleaning",
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"disconnected='" UINT32_FORMAT "' made_not_entrant='" UINT32_FORMAT "'",
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disconnected, made_not_entrant);
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// Shut off compiler. Sweeper will start over with a new stack scan and
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// traversal cycle and turn it back on if it clears enough space.
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@ -435,3 +401,38 @@ void NMethodSweeper::speculative_disconnect_nmethods(bool is_full) {
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}
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#endif
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}
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// Print out some state information about the current sweep and the
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// state of the code cache if it's requested.
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void NMethodSweeper::log_sweep(const char* msg, const char* format, ...) {
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if (PrintMethodFlushing) {
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ttyLocker ttyl;
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tty->print("### sweeper: %s ", msg);
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if (format != NULL) {
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va_list ap;
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va_start(ap, format);
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tty->vprint(format, ap);
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va_end(ap);
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}
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tty->print_cr(" total_blobs='" UINT32_FORMAT "' nmethods='" UINT32_FORMAT "'"
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" adapters='" UINT32_FORMAT "' free_code_cache='" SIZE_FORMAT "'",
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CodeCache::nof_blobs(), CodeCache::nof_nmethods(), CodeCache::nof_adapters(), CodeCache::unallocated_capacity());
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}
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if (LogCompilation && (xtty != NULL)) {
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ttyLocker ttyl;
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xtty->begin_elem("sweeper state='%s' traversals=`" INTX_FORMAT "' ", msg, (intx)traversal_count());
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if (format != NULL) {
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va_list ap;
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va_start(ap, format);
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xtty->vprint(format, ap);
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va_end(ap);
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}
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xtty->print(" total_blobs='" UINT32_FORMAT "' nmethods='" UINT32_FORMAT "'"
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" adapters='" UINT32_FORMAT "' free_code_cache='" SIZE_FORMAT "'",
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CodeCache::nof_blobs(), CodeCache::nof_nmethods(), CodeCache::nof_adapters(), CodeCache::unallocated_capacity());
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xtty->stamp();
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xtty->end_elem();
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}
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}
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