--- old/src/hotspot/share/runtime/synchronizer.cpp 2020-07-13 15:31:53.000000000 -0400 +++ new/src/hotspot/share/runtime/synchronizer.cpp 2020-07-13 15:31:52.000000000 -0400 @@ -491,15 +491,11 @@ if (mark.has_monitor()) { ObjectMonitor* const m = mark.monitor(); - if (AsyncDeflateIdleMonitors) { - // An async deflation can race us before we manage to make the - // ObjectMonitor busy by setting the owner below. If we detect - // that race we just bail out to the slow-path here. - if (m->object() == NULL) { - return false; - } - } else { - assert(m->object() == obj, "invariant"); + // An async deflation can race us before we manage to make the + // ObjectMonitor busy by setting the owner below. If we detect + // that race we just bail out to the slow-path here. + if (m->object() == NULL) { + return false; } Thread* const owner = (Thread *) m->_owner; @@ -986,9 +982,8 @@ intptr_t ObjectSynchronizer::FastHashCode(Thread* self, oop obj) { if (UseBiasedLocking) { // NOTE: many places throughout the JVM do not expect a safepoint - // to be taken here, in particular most operations on perm gen - // objects. However, we only ever bias Java instances and all of - // the call sites of identity_hash that might revoke biases have + // to be taken here. However, we only ever bias Java instances and all + // of the call sites of identity_hash that might revoke biases have // been checked to make sure they can handle a safepoint. The // added check of the bias pattern is to avoid useless calls to // thread-local storage. @@ -1193,8 +1188,6 @@ } // CASE: inflated. Mark (tagged pointer) points to an ObjectMonitor. - // The Object:ObjectMonitor relationship is stable as long as we're - // not at a safepoint and AsyncDeflateIdleMonitors is false. if (mark.has_monitor()) { // The first stage of async deflation does not affect any field // used by this comparison so the ObjectMonitor* is usable here. @@ -1294,9 +1287,6 @@ } bool ObjectSynchronizer::is_async_deflation_needed() { - if (!AsyncDeflateIdleMonitors) { - return false; - } if (is_async_deflation_requested()) { // Async deflation request. return true; @@ -1313,48 +1303,33 @@ return false; } -bool ObjectSynchronizer::is_safepoint_deflation_needed() { - return !AsyncDeflateIdleMonitors && - monitors_used_above_threshold(); // Too many monitors in use. -} - bool ObjectSynchronizer::request_deflate_idle_monitors() { bool is_JavaThread = Thread::current()->is_Java_thread(); bool ret_code = false; - if (AsyncDeflateIdleMonitors) { - jlong last_time = last_async_deflation_time_ns(); - set_is_async_deflation_requested(true); - { - MonitorLocker ml(Service_lock, Mutex::_no_safepoint_check_flag); - ml.notify_all(); - } - const int N_CHECKS = 5; - for (int i = 0; i < N_CHECKS; i++) { // sleep for at most 5 seconds - if (last_async_deflation_time_ns() > last_time) { - log_info(monitorinflation)("Async Deflation happened after %d check(s).", i); - ret_code = true; - break; - } - if (is_JavaThread) { - // JavaThread has to honor the blocking protocol. - ThreadBlockInVM tbivm(JavaThread::current()); - os::naked_short_sleep(999); // sleep for almost 1 second - } else { - os::naked_short_sleep(999); // sleep for almost 1 second - } + jlong last_time = last_async_deflation_time_ns(); + set_is_async_deflation_requested(true); + { + MonitorLocker ml(Service_lock, Mutex::_no_safepoint_check_flag); + ml.notify_all(); + } + const int N_CHECKS = 5; + for (int i = 0; i < N_CHECKS; i++) { // sleep for at most 5 seconds + if (last_async_deflation_time_ns() > last_time) { + log_info(monitorinflation)("Async Deflation happened after %d check(s).", i); + ret_code = true; + break; } - if (!ret_code) { - log_info(monitorinflation)("Async Deflation DID NOT happen after %d checks.", N_CHECKS); + if (is_JavaThread) { + // JavaThread has to honor the blocking protocol. + ThreadBlockInVM tbivm(JavaThread::current()); + os::naked_short_sleep(999); // sleep for almost 1 second + } else { + os::naked_short_sleep(999); // sleep for almost 1 second } - } else { - // Only need to force this safepoint if we are not using async - // deflation. The VMThread won't call this function before the - // final safepoint if we are not using async deflation so we - // don't have to reason about the VMThread executing a VM-op here. - VM_ForceSafepoint force_safepoint_op; - VMThread::execute(&force_safepoint_op); - ret_code = true; + } + if (!ret_code) { + log_info(monitorinflation)("Async Deflation DID NOT happen after %d checks.", N_CHECKS); } return ret_code; @@ -1396,9 +1371,9 @@ // ObjectMonitor Lifecycle // ----------------------- // Inflation unlinks monitors from om_list_globals._free_list or a per-thread -// free list and associates them with objects. Deflation -- which occurs at -// STW-time or asynchronously -- disassociates idle monitors from objects. -// Such scavenged monitors are returned to the om_list_globals._free_list. +// free list and associates them with objects. Async deflation disassociates +// idle monitors from objects. Such scavenged monitors are returned to the +// om_list_globals._free_list. // // ObjectMonitors reside in type-stable memory (TSM) and are immortal. // @@ -1411,7 +1386,7 @@ ObjectMonitor* ObjectSynchronizer::om_alloc(Thread* self) { // A large MAXPRIVATE value reduces both list lock contention // and list coherency traffic, but also tends to increase the - // number of ObjectMonitors in circulation as well as the STW + // number of ObjectMonitors in circulation as well as the // scavenge costs. As usual, we lean toward time in space-time // tradeoffs. const int MAXPRIVATE = 1024; @@ -1447,23 +1422,21 @@ break; // No more are available. } guarantee(take->object() == NULL, "invariant"); - if (AsyncDeflateIdleMonitors) { - // We allowed 3 field values to linger during async deflation. - // Clear or restore them as appropriate. - take->set_header(markWord::zero()); - // DEFLATER_MARKER is the only non-NULL value we should see here. - take->try_set_owner_from(DEFLATER_MARKER, NULL); - if (take->contentions() < 0) { - // Add back max_jint to restore the contentions field to its - // proper value. - take->add_to_contentions(max_jint); + // We allowed 3 field values to linger during async deflation. + // Clear or restore them as appropriate. + take->set_header(markWord::zero()); + // DEFLATER_MARKER is the only non-NULL value we should see here. + take->try_set_owner_from(DEFLATER_MARKER, NULL); + if (take->contentions() < 0) { + // Add back max_jint to restore the contentions field to its + // proper value. + take->add_to_contentions(max_jint); #ifdef ASSERT - jint l_contentions = take->contentions(); + jint l_contentions = take->contentions(); + assert(l_contentions >= 0, "must not be negative: l_contentions=%d, contentions=%d", + l_contentions, take->contentions()); #endif - assert(l_contentions >= 0, "must not be negative: l_contentions=%d, contentions=%d", - l_contentions, take->contentions()); - } } take->Recycle(); // Since we're taking from the global free-list, take must be Free. @@ -1529,8 +1502,8 @@ // // Key constraint: all ObjectMonitors on a thread's free list and the global // free list must have their object field set to null. This prevents the -// scavenger -- deflate_monitor_list() or deflate_monitor_list_using_JT() -// -- from reclaiming them while we are trying to release them. +// scavenger -- deflate_monitor_list_using_JT() -- from reclaiming them +// while we are trying to release them. void ObjectSynchronizer::om_release(Thread* self, ObjectMonitor* m, bool from_per_thread_alloc) { @@ -1639,15 +1612,13 @@ // // We currently call om_flush() from Threads::remove() before the // thread has been excised from the thread list and is no longer a -// mutator. This means that om_flush() cannot run concurrently with -// a safepoint and interleave with deflate_idle_monitors(). In -// particular, this ensures that the thread's in-use monitors are -// scanned by a GC safepoint, either via Thread::oops_do() (before -// om_flush() is called) or via ObjectSynchronizer::oops_do() (after -// om_flush() is called). +// mutator. In particular, this ensures that the thread's in-use +// monitors are scanned by a GC safepoint, either via Thread::oops_do() +// (before om_flush() is called) or via ObjectSynchronizer::oops_do() +// (after om_flush() is called). // -// With AsyncDeflateIdleMonitors, deflate_global_idle_monitors_using_JT() -// and deflate_per_thread_idle_monitors_using_JT() (in another thread) can +// deflate_global_idle_monitors_using_JT() and +// deflate_per_thread_idle_monitors_using_JT() (in another thread) can // run at the same time as om_flush() so we have to follow a careful // protocol to prevent list corruption. @@ -1701,9 +1672,11 @@ cur_om = unmarked_next(cur_om); } guarantee(in_use_tail != NULL, "invariant"); +#ifdef ASSERT int l_om_in_use_count = Atomic::load(&self->om_in_use_count); - ADIM_guarantee(l_om_in_use_count == in_use_count, "in-use counts don't match: " - "l_om_in_use_count=%d, in_use_count=%d", l_om_in_use_count, in_use_count); + assert(l_om_in_use_count == in_use_count, "in-use counts don't match: " + "l_om_in_use_count=%d, in_use_count=%d", l_om_in_use_count, in_use_count); +#endif Atomic::store(&self->om_in_use_count, 0); // Clear the in-use list head (which also unlocks it): Atomic::store(&self->om_in_use_list, (ObjectMonitor*)NULL); @@ -1744,9 +1717,11 @@ } } guarantee(free_tail != NULL, "invariant"); +#ifdef ASSERT int l_om_free_count = Atomic::load(&self->om_free_count); - ADIM_guarantee(l_om_free_count == free_count, "free counts don't match: " - "l_om_free_count=%d, free_count=%d", l_om_free_count, free_count); + assert(l_om_free_count == free_count, "free counts don't match: " + "l_om_free_count=%d, free_count=%d", l_om_free_count, free_count); +#endif Atomic::store(&self->om_free_count, 0); Atomic::store(&self->om_free_list, (ObjectMonitor*)NULL); om_unlock(free_list); @@ -1825,7 +1800,6 @@ ObjectMonitor* inf = mark.monitor(); markWord dmw = inf->header(); assert(dmw.is_neutral(), "invariant: header=" INTPTR_FORMAT, dmw.value()); - assert(AsyncDeflateIdleMonitors || inf->object() == object, "invariant"); assert(ObjectSynchronizer::verify_objmon_isinpool(inf), "monitor is invalid"); return inf; } @@ -1911,7 +1885,7 @@ markWord dmw = mark.displaced_mark_helper(); // Catch if the object's header is not neutral (not locked and // not marked is what we care about here). - ADIM_guarantee(dmw.is_neutral(), "invariant: header=" INTPTR_FORMAT, dmw.value()); + assert(dmw.is_neutral(), "invariant: header=" INTPTR_FORMAT, dmw.value()); // Setup monitor fields to proper values -- prepare the monitor m->set_header(dmw); @@ -1921,11 +1895,7 @@ // Note that a thread can inflate an object // that it has stack-locked -- as might happen in wait() -- directly // with CAS. That is, we can avoid the xchg-NULL .... ST idiom. - if (AsyncDeflateIdleMonitors) { - m->set_owner_from(NULL, DEFLATER_MARKER, mark.locker()); - } else { - m->set_owner_from(NULL, mark.locker()); - } + m->set_owner_from(NULL, DEFLATER_MARKER, mark.locker()); m->set_object(object); // TODO-FIXME: assert BasicLock->dhw != 0. @@ -1965,15 +1935,13 @@ // Catch if the object's header is not neutral (not locked and // not marked is what we care about here). - ADIM_guarantee(mark.is_neutral(), "invariant: header=" INTPTR_FORMAT, mark.value()); + assert(mark.is_neutral(), "invariant: header=" INTPTR_FORMAT, mark.value()); ObjectMonitor* m = om_alloc(self); // prepare m for installation - set monitor to initial state m->Recycle(); m->set_header(mark); - if (AsyncDeflateIdleMonitors) { - // DEFLATER_MARKER is the only non-NULL value we should see here. - m->try_set_owner_from(DEFLATER_MARKER, NULL); - } + // DEFLATER_MARKER is the only non-NULL value we should see here. + m->try_set_owner_from(DEFLATER_MARKER, NULL); m->set_object(object); m->_Responsible = NULL; m->_SpinDuration = ObjectMonitor::Knob_SpinLimit; // consider: keep metastats by type/class @@ -2013,45 +1981,11 @@ } -// We maintain a list of in-use monitors for each thread. -// -// For safepoint based deflation: -// deflate_thread_local_monitors() scans a single thread's in-use list, while -// deflate_idle_monitors() scans only a global list of in-use monitors which -// is populated only as a thread dies (see om_flush()). -// -// These operations are called at all safepoints, immediately after mutators -// are stopped, but before any objects have moved. Collectively they traverse -// the population of in-use monitors, deflating where possible. The scavenged -// monitors are returned to the global monitor free list. -// -// Beware that we scavenge at *every* stop-the-world point. Having a large -// number of monitors in-use could negatively impact performance. We also want -// to minimize the total # of monitors in circulation, as they incur a small -// footprint penalty. -// -// Perversely, the heap size -- and thus the STW safepoint rate -- -// typically drives the scavenge rate. Large heaps can mean infrequent GC, -// which in turn can mean large(r) numbers of ObjectMonitors in circulation. -// This is an unfortunate aspect of this design. -// -// For async deflation: -// If a special deflation request is made, then the safepoint based -// deflation mechanism is used. Otherwise, an async deflation request -// is registered with the ServiceThread and it is notified. - -void ObjectSynchronizer::do_safepoint_work(DeflateMonitorCounters* counters) { +// An async deflation request is registered with the ServiceThread +// and it is notified. +void ObjectSynchronizer::do_safepoint_work() { assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint"); - // The per-thread in-use lists are handled in - // ParallelSPCleanupThreadClosure::do_thread(). - - if (!AsyncDeflateIdleMonitors) { - // Use the older mechanism for the global in-use list. - ObjectSynchronizer::deflate_idle_monitors(counters); - return; - } - log_debug(monitorinflation)("requesting async deflation of idle monitors."); // Request deflation of idle monitors by the ServiceThread: set_is_async_deflation_requested(true); @@ -2061,85 +1995,10 @@ if (log_is_enabled(Debug, monitorinflation)) { // exit_globals()'s call to audit_and_print_stats() is done // at the Info level and not at a safepoint. - // For safepoint based deflation, audit_and_print_stats() is called - // in ObjectSynchronizer::finish_deflate_idle_monitors() at the - // Debug level at a safepoint. ObjectSynchronizer::audit_and_print_stats(false /* on_exit */); } } -// Deflate a single monitor if not in-use -// Return true if deflated, false if in-use -bool ObjectSynchronizer::deflate_monitor(ObjectMonitor* mid, oop obj, - ObjectMonitor** free_head_p, - ObjectMonitor** free_tail_p) { - bool deflated; - // Normal case ... The monitor is associated with obj. - const markWord mark = obj->mark(); - guarantee(mark == markWord::encode(mid), "should match: mark=" - INTPTR_FORMAT ", encoded mid=" INTPTR_FORMAT, mark.value(), - markWord::encode(mid).value()); - // Make sure that mark.monitor() and markWord::encode() agree: - guarantee(mark.monitor() == mid, "should match: monitor()=" INTPTR_FORMAT - ", mid=" INTPTR_FORMAT, p2i(mark.monitor()), p2i(mid)); - const markWord dmw = mid->header(); - guarantee(dmw.is_neutral(), "invariant: header=" INTPTR_FORMAT, dmw.value()); - - if (mid->is_busy()) { - // Easy checks are first - the ObjectMonitor is busy so no deflation. - deflated = false; - } else { - // Deflate the monitor if it is no longer being used - // It's idle - scavenge and return to the global free list - // plain old deflation ... - if (log_is_enabled(Trace, monitorinflation)) { - ResourceMark rm; - log_trace(monitorinflation)("deflate_monitor: " - "object=" INTPTR_FORMAT ", mark=" - INTPTR_FORMAT ", type='%s'", p2i(obj), - mark.value(), obj->klass()->external_name()); - } - - // Restore the header back to obj - obj->release_set_mark(dmw); - if (AsyncDeflateIdleMonitors) { - // clear() expects the owner field to be NULL. - // DEFLATER_MARKER is the only non-NULL value we should see here. - mid->try_set_owner_from(DEFLATER_MARKER, NULL); - } - mid->clear(); - - assert(mid->object() == NULL, "invariant: object=" INTPTR_FORMAT, - p2i(mid->object())); - assert(mid->is_free(), "invariant"); - - // Move the deflated ObjectMonitor to the working free list - // defined by free_head_p and free_tail_p. - if (*free_head_p == NULL) *free_head_p = mid; - if (*free_tail_p != NULL) { - // We append to the list so the caller can use mid->_next_om - // to fix the linkages in its context. - ObjectMonitor* prevtail = *free_tail_p; - // Should have been cleaned up by the caller: - // Note: Should not have to lock prevtail here since we're at a - // safepoint and ObjectMonitors on the local free list should - // not be accessed in parallel. -#ifdef ASSERT - ObjectMonitor* l_next_om = prevtail->next_om(); -#endif - assert(l_next_om == NULL, "must be NULL: _next_om=" INTPTR_FORMAT, p2i(l_next_om)); - prevtail->set_next_om(mid); - } - *free_tail_p = mid; - // At this point, mid->_next_om still refers to its current - // value and another ObjectMonitor's _next_om field still - // refers to this ObjectMonitor. Those linkages have to be - // cleaned up by the caller who has the complete context. - deflated = true; - } - return deflated; -} - // Deflate the specified ObjectMonitor if not in-use using a JavaThread. // Returns true if it was deflated and false otherwise. // @@ -2156,7 +2015,6 @@ bool ObjectSynchronizer::deflate_monitor_using_JT(ObjectMonitor* mid, ObjectMonitor** free_head_p, ObjectMonitor** free_tail_p) { - assert(AsyncDeflateIdleMonitors, "sanity check"); assert(Thread::current()->is_Java_thread(), "precondition"); // A newly allocated ObjectMonitor should not be seen here so we // avoid an endless inflate/deflate cycle. @@ -2245,8 +2103,8 @@ // prevtail should have been cleaned up by the caller: #ifdef ASSERT ObjectMonitor* l_next_om = unmarked_next(prevtail); -#endif assert(l_next_om == NULL, "must be NULL: _next_om=" INTPTR_FORMAT, p2i(l_next_om)); +#endif om_lock(prevtail); prevtail->set_next_om(mid); // prevtail now points to mid (and is unlocked) } @@ -2262,56 +2120,6 @@ return true; // Success, ObjectMonitor has been deflated. } -// Walk a given monitor list, and deflate idle monitors. -// The given list could be a per-thread list or a global list. -// -// In the case of parallel processing of thread local monitor lists, -// work is done by Threads::parallel_threads_do() which ensures that -// each Java thread is processed by exactly one worker thread, and -// thus avoid conflicts that would arise when worker threads would -// process the same monitor lists concurrently. -// -// See also ParallelSPCleanupTask and -// SafepointSynchronize::do_cleanup_tasks() in safepoint.cpp and -// Threads::parallel_java_threads_do() in thread.cpp. -int ObjectSynchronizer::deflate_monitor_list(ObjectMonitor** list_p, - int* count_p, - ObjectMonitor** free_head_p, - ObjectMonitor** free_tail_p) { - ObjectMonitor* cur_mid_in_use = NULL; - ObjectMonitor* mid = NULL; - ObjectMonitor* next = NULL; - int deflated_count = 0; - - // This list walk executes at a safepoint and does not race with any - // other list walkers. - - for (mid = Atomic::load(list_p); mid != NULL; mid = next) { - next = unmarked_next(mid); - oop obj = (oop) mid->object(); - if (obj != NULL && deflate_monitor(mid, obj, free_head_p, free_tail_p)) { - // Deflation succeeded and already updated free_head_p and - // free_tail_p as needed. Finish the move to the local free list - // by unlinking mid from the global or per-thread in-use list. - if (cur_mid_in_use == NULL) { - // mid is the list head so switch the list head to next: - Atomic::store(list_p, next); - } else { - // Switch cur_mid_in_use's next field to next: - cur_mid_in_use->set_next_om(next); - } - // At this point mid is disconnected from the in-use list. - deflated_count++; - Atomic::dec(count_p); - // mid is current tail in the free_head_p list so NULL terminate it: - mid->set_next_om(NULL); - } else { - cur_mid_in_use = mid; - } - } - return deflated_count; -} - // Walk a given ObjectMonitor list and deflate idle ObjectMonitors using // a JavaThread. Returns the number of deflated ObjectMonitors. The given // list could be a per-thread in-use list or the global in-use list. @@ -2323,7 +2131,6 @@ ObjectMonitor** free_head_p, ObjectMonitor** free_tail_p, ObjectMonitor** saved_mid_in_use_p) { - assert(AsyncDeflateIdleMonitors, "sanity check"); JavaThread* self = JavaThread::current(); ObjectMonitor* cur_mid_in_use = NULL; @@ -2453,75 +2260,6 @@ return deflated_count; } -void ObjectSynchronizer::prepare_deflate_idle_monitors(DeflateMonitorCounters* counters) { - counters->n_in_use = 0; // currently associated with objects - counters->n_in_circulation = 0; // extant - counters->n_scavenged = 0; // reclaimed (global and per-thread) - counters->per_thread_scavenged = 0; // per-thread scavenge total - counters->per_thread_times = 0.0; // per-thread scavenge times -} - -void ObjectSynchronizer::deflate_idle_monitors(DeflateMonitorCounters* counters) { - assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint"); - - if (AsyncDeflateIdleMonitors) { - // Nothing to do when global idle ObjectMonitors are deflated using - // a JavaThread. - return; - } - - bool deflated = false; - - ObjectMonitor* free_head_p = NULL; // Local SLL of scavenged monitors - ObjectMonitor* free_tail_p = NULL; - elapsedTimer timer; - - if (log_is_enabled(Info, monitorinflation)) { - timer.start(); - } - - // Note: the thread-local monitors lists get deflated in - // a separate pass. See deflate_thread_local_monitors(). - - // For moribund threads, scan om_list_globals._in_use_list - int deflated_count = 0; - if (Atomic::load(&om_list_globals._in_use_list) != NULL) { - // Update n_in_circulation before om_list_globals._in_use_count is - // updated by deflation. - Atomic::add(&counters->n_in_circulation, - Atomic::load(&om_list_globals._in_use_count)); - - deflated_count = deflate_monitor_list(&om_list_globals._in_use_list, - &om_list_globals._in_use_count, - &free_head_p, &free_tail_p); - Atomic::add(&counters->n_in_use, Atomic::load(&om_list_globals._in_use_count)); - } - - if (free_head_p != NULL) { - // Move the deflated ObjectMonitors back to the global free list. - guarantee(free_tail_p != NULL && deflated_count > 0, "invariant"); -#ifdef ASSERT - ObjectMonitor* l_next_om = free_tail_p->next_om(); -#endif - assert(l_next_om == NULL, "must be NULL: _next_om=" INTPTR_FORMAT, p2i(l_next_om)); - prepend_list_to_global_free_list(free_head_p, free_tail_p, deflated_count); - Atomic::add(&counters->n_scavenged, deflated_count); - } - timer.stop(); - - LogStreamHandle(Debug, monitorinflation) lsh_debug; - LogStreamHandle(Info, monitorinflation) lsh_info; - LogStream* ls = NULL; - if (log_is_enabled(Debug, monitorinflation)) { - ls = &lsh_debug; - } else if (deflated_count != 0 && log_is_enabled(Info, monitorinflation)) { - ls = &lsh_info; - } - if (ls != NULL) { - ls->print_cr("deflating global idle monitors, %3.7f secs, %d monitors", timer.seconds(), deflated_count); - } -} - class HandshakeForDeflation : public HandshakeClosure { public: HandshakeForDeflation() : HandshakeClosure("HandshakeForDeflation") {} @@ -2533,8 +2271,6 @@ }; void ObjectSynchronizer::deflate_idle_monitors_using_JT() { - assert(AsyncDeflateIdleMonitors, "sanity check"); - // Deflate any global idle monitors. deflate_global_idle_monitors_using_JT(); @@ -2568,7 +2304,7 @@ // (or a safepoint) for safety. ObjectMonitor* list = Atomic::load(&om_list_globals._wait_list); - ADIM_guarantee(list != NULL, "om_list_globals._wait_list must not be NULL"); + assert(list != NULL, "om_list_globals._wait_list must not be NULL"); int count = Atomic::load(&om_list_globals._wait_count); Atomic::store(&om_list_globals._wait_count, 0); Atomic::store(&om_list_globals._wait_list, (ObjectMonitor*)NULL); @@ -2576,13 +2312,17 @@ // Find the tail for prepend_list_to_common(). No need to mark // ObjectMonitors for this list walk since only the deflater // thread manages the wait list. +#ifdef ASSERT int l_count = 0; +#endif ObjectMonitor* tail = NULL; for (ObjectMonitor* n = list; n != NULL; n = unmarked_next(n)) { tail = n; +#ifdef ASSERT l_count++; +#endif } - ADIM_guarantee(count == l_count, "count=%d != l_count=%d", count, l_count); + assert(count == l_count, "count=%d != l_count=%d", count, l_count); // Will execute a safepoint if !ThreadLocalHandshakes: HandshakeForDeflation hfd_hc; @@ -2598,7 +2338,6 @@ // Deflate global idle ObjectMonitors using a JavaThread. // void ObjectSynchronizer::deflate_global_idle_monitors_using_JT() { - assert(AsyncDeflateIdleMonitors, "sanity check"); assert(Thread::current()->is_Java_thread(), "precondition"); JavaThread* self = JavaThread::current(); @@ -2608,7 +2347,6 @@ // Deflate the specified JavaThread's idle ObjectMonitors using a JavaThread. // void ObjectSynchronizer::deflate_per_thread_idle_monitors_using_JT(JavaThread* target) { - assert(AsyncDeflateIdleMonitors, "sanity check"); assert(Thread::current()->is_Java_thread(), "precondition"); deflate_common_idle_monitors_using_JT(false /* !is_global */, target); @@ -2664,8 +2402,8 @@ // all out. #ifdef ASSERT ObjectMonitor* l_next_om = unmarked_next(free_tail_p); -#endif assert(l_next_om == NULL, "must be NULL: _next_om=" INTPTR_FORMAT, p2i(l_next_om)); +#endif prepend_list_to_global_wait_list(free_head_p, free_tail_p, local_deflated_count); @@ -2711,94 +2449,6 @@ } } -void ObjectSynchronizer::finish_deflate_idle_monitors(DeflateMonitorCounters* counters) { - // Report the cumulative time for deflating each thread's idle - // monitors. Note: if the work is split among more than one - // worker thread, then the reported time will likely be more - // than a beginning to end measurement of the phase. - log_info(safepoint, cleanup)("deflating per-thread idle monitors, %3.7f secs, monitors=%d", counters->per_thread_times, counters->per_thread_scavenged); - - if (AsyncDeflateIdleMonitors) { - // Nothing to do when idle ObjectMonitors are deflated using - // a JavaThread. - return; - } - - if (log_is_enabled(Debug, monitorinflation)) { - // exit_globals()'s call to audit_and_print_stats() is done - // at the Info level and not at a safepoint. - // For async deflation, audit_and_print_stats() is called in - // ObjectSynchronizer::do_safepoint_work() at the Debug level - // at a safepoint. - ObjectSynchronizer::audit_and_print_stats(false /* on_exit */); - } else if (log_is_enabled(Info, monitorinflation)) { - log_info(monitorinflation)("global_population=%d, global_in_use_count=%d, " - "global_free_count=%d, global_wait_count=%d", - Atomic::load(&om_list_globals._population), - Atomic::load(&om_list_globals._in_use_count), - Atomic::load(&om_list_globals._free_count), - Atomic::load(&om_list_globals._wait_count)); - } - - OM_PERFDATA_OP(Deflations, inc(counters->n_scavenged)); - OM_PERFDATA_OP(MonExtant, set_value(counters->n_in_circulation)); - - GVars.stw_random = os::random(); - GVars.stw_cycle++; -} - -void ObjectSynchronizer::deflate_thread_local_monitors(Thread* thread, DeflateMonitorCounters* counters) { - assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint"); - - if (AsyncDeflateIdleMonitors) { - // Nothing to do when per-thread idle ObjectMonitors are deflated - // using a JavaThread. - return; - } - - ObjectMonitor* free_head_p = NULL; // Local SLL of scavenged monitors - ObjectMonitor* free_tail_p = NULL; - elapsedTimer timer; - - if (log_is_enabled(Info, safepoint, cleanup) || - log_is_enabled(Info, monitorinflation)) { - timer.start(); - } - - // Update n_in_circulation before om_in_use_count is updated by deflation. - Atomic::add(&counters->n_in_circulation, Atomic::load(&thread->om_in_use_count)); - - int deflated_count = deflate_monitor_list(&thread->om_in_use_list, &thread->om_in_use_count, &free_head_p, &free_tail_p); - Atomic::add(&counters->n_in_use, Atomic::load(&thread->om_in_use_count)); - - if (free_head_p != NULL) { - // Move the deflated ObjectMonitors back to the global free list. - guarantee(free_tail_p != NULL && deflated_count > 0, "invariant"); -#ifdef ASSERT - ObjectMonitor* l_next_om = free_tail_p->next_om(); -#endif - assert(l_next_om == NULL, "must be NULL: _next_om=" INTPTR_FORMAT, p2i(l_next_om)); - prepend_list_to_global_free_list(free_head_p, free_tail_p, deflated_count); - Atomic::add(&counters->n_scavenged, deflated_count); - Atomic::add(&counters->per_thread_scavenged, deflated_count); - } - - timer.stop(); - counters->per_thread_times += timer.seconds(); - - LogStreamHandle(Debug, monitorinflation) lsh_debug; - LogStreamHandle(Info, monitorinflation) lsh_info; - LogStream* ls = NULL; - if (log_is_enabled(Debug, monitorinflation)) { - ls = &lsh_debug; - } else if (deflated_count != 0 && log_is_enabled(Info, monitorinflation)) { - ls = &lsh_info; - } - if (ls != NULL) { - ls->print_cr("jt=" INTPTR_FORMAT ": deflating per-thread idle monitors, %3.7f secs, %d monitors", p2i(thread), timer.seconds(), deflated_count); - } -} - // Monitor cleanup on JavaThread::exit // Iterate through monitor cache and attempt to release thread's monitors @@ -2824,7 +2474,7 @@ // A simple optimization is to add a per-thread flag that indicates a thread // called jni_monitorenter() during its lifetime. // -// Instead of No_Savepoint_Verifier it might be cheaper to +// Instead of NoSafepointVerifier it might be cheaper to // use an idiom of the form: // auto int tmp = SafepointSynchronize::_safepoint_counter ; // @@ -2883,8 +2533,6 @@ // aid; pass 'true' for the 'on_exit' parameter to have in-use monitor // details logged at the Info level and 'false' for the 'on_exit' // parameter to have in-use monitor details logged at the Trace level. -// deflate_monitor_list() no longer uses spin-locking so be careful -// when adding audit_and_print_stats() calls at a safepoint. // void ObjectSynchronizer::audit_and_print_stats(bool on_exit) { assert(on_exit || SafepointSynchronize::is_at_safepoint(), "invariant"); @@ -2983,11 +2631,6 @@ "field: _header=" INTPTR_FORMAT, p2i(jt), p2i(n), n->header().value()); *error_cnt_p = *error_cnt_p + 1; - } else if (!AsyncDeflateIdleMonitors) { - out->print_cr("ERROR: monitor=" INTPTR_FORMAT ": free global monitor " - "must have NULL _header field: _header=" INTPTR_FORMAT, - p2i(n), n->header().value()); - *error_cnt_p = *error_cnt_p + 1; } } if (n->object() != NULL) {