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#include "gc/shenandoah/shenandoahConcurrentGC.hpp"
#include "gc/shenandoah/shenandoahControlThread.hpp"
#include "gc/shenandoah/shenandoahDegeneratedGC.hpp"
#include "gc/shenandoah/shenandoahFreeSet.hpp"
#include "gc/shenandoah/shenandoahFullGC.hpp"
- #include "gc/shenandoah/shenandoahPhaseTimings.hpp"
+ #include "gc/shenandoah/shenandoahGeneration.hpp"
#include "gc/shenandoah/shenandoahHeap.inline.hpp"
- #include "gc/shenandoah/shenandoahMark.inline.hpp"
#include "gc/shenandoah/shenandoahMonitoringSupport.hpp"
- #include "gc/shenandoah/shenandoahOopClosures.inline.hpp"
- #include "gc/shenandoah/shenandoahRootProcessor.inline.hpp"
+ #include "gc/shenandoah/shenandoahPacer.inline.hpp"
#include "gc/shenandoah/shenandoahUtils.hpp"
- #include "gc/shenandoah/shenandoahVMOperations.hpp"
- #include "gc/shenandoah/shenandoahWorkerPolicy.hpp"
#include "gc/shenandoah/heuristics/shenandoahHeuristics.hpp"
- #include "memory/iterator.hpp"
+ #include "gc/shenandoah/mode/shenandoahMode.hpp"
+ #include "logging/log.hpp"
#include "memory/metaspaceUtils.hpp"
#include "memory/metaspaceStats.hpp"
- #include "memory/universe.hpp"
- #include "runtime/atomic.hpp"
ShenandoahControlThread::ShenandoahControlThread() :
- ConcurrentGCThread(),
- _alloc_failure_waiters_lock(Mutex::safepoint-2, "ShenandoahAllocFailureGC_lock", true),
- _gc_waiters_lock(Mutex::safepoint-2, "ShenandoahRequestedGC_lock", true),
- _periodic_task(this),
+ ShenandoahController(),
_requested_gc_cause(GCCause::_no_cause_specified),
- _degen_point(ShenandoahGC::_degenerated_outside_cycle),
- _allocs_seen(0) {
+ _degen_point(ShenandoahGC::_degenerated_outside_cycle) {
set_name("Shenandoah Control Thread");
- reset_gc_id();
create_and_start();
- _periodic_task.enroll();
- if (ShenandoahPacing) {
- _periodic_pacer_notify_task.enroll();
- }
- }
-
- ShenandoahControlThread::~ShenandoahControlThread() {
- // This is here so that super is called.
- }
-
- void ShenandoahPeriodicTask::task() {
- _thread->handle_force_counters_update();
- _thread->handle_counters_update();
- }
-
- void ShenandoahPeriodicPacerNotify::task() {
- assert(ShenandoahPacing, "Should not be here otherwise");
- ShenandoahHeap::heap()->pacer()->notify_waiters();
}
void ShenandoahControlThread::run_service() {
- ShenandoahHeap* heap = ShenandoahHeap::heap();
+ ShenandoahHeap* const heap = ShenandoahHeap::heap();
- GCMode default_mode = concurrent_normal;
- GCCause::Cause default_cause = GCCause::_shenandoah_concurrent_gc;
+ const GCMode default_mode = concurrent_normal;
+ const GCCause::Cause default_cause = GCCause::_shenandoah_concurrent_gc;
int sleep = ShenandoahControlIntervalMin;
double last_shrink_time = os::elapsedTime();
double last_sleep_adjust_time = os::elapsedTime();
// Shrink period avoids constantly polling regions for shrinking.
// Having a period 10x lower than the delay would mean we hit the
// shrinking with lag of less than 1/10-th of true delay.
// ShenandoahUncommitDelay is in msecs, but shrink_period is in seconds.
- double shrink_period = (double)ShenandoahUncommitDelay / 1000 / 10;
+ const double shrink_period = (double)ShenandoahUncommitDelay / 1000 / 10;
- ShenandoahCollectorPolicy* policy = heap->shenandoah_policy();
- ShenandoahHeuristics* heuristics = heap->heuristics();
+ ShenandoahCollectorPolicy* const policy = heap->shenandoah_policy();
+ ShenandoahHeuristics* const heuristics = heap->heuristics();
while (!in_graceful_shutdown() && !should_terminate()) {
// Figure out if we have pending requests.
- bool alloc_failure_pending = _alloc_failure_gc.is_set();
- bool is_gc_requested = _gc_requested.is_set();
- GCCause::Cause requested_gc_cause = _requested_gc_cause;
- bool explicit_gc_requested = is_gc_requested && is_explicit_gc(requested_gc_cause);
- bool implicit_gc_requested = is_gc_requested && !is_explicit_gc(requested_gc_cause);
+ const bool alloc_failure_pending = _alloc_failure_gc.is_set();
+ const bool is_gc_requested = _gc_requested.is_set();
+ const GCCause::Cause requested_gc_cause = _requested_gc_cause;
- // This control loop iteration have seen this much allocations.
- size_t allocs_seen = Atomic::xchg(&_allocs_seen, (size_t)0, memory_order_relaxed);
+ // This control loop iteration has seen this much allocation.
+ const size_t allocs_seen = reset_allocs_seen();
// Check if we have seen a new target for soft max heap size.
- bool soft_max_changed = check_soft_max_changed();
+ const bool soft_max_changed = heap->check_soft_max_changed();
// Choose which GC mode to run in. The block below should select a single mode.
GCMode mode = none;
GCCause::Cause cause = GCCause::_last_gc_cause;
ShenandoahGC::ShenandoahDegenPoint degen_point = ShenandoahGC::_degenerated_unset;
if (alloc_failure_pending) {
// Allocation failure takes precedence: we have to deal with it first thing
- log_info(gc)("Trigger: Handle Allocation Failure");
+ heuristics->log_trigger("Handle Allocation Failure");
cause = GCCause::_allocation_failure;
// Consume the degen point, and seed it with default value
degen_point = _degen_point;
} else {
heuristics->record_allocation_failure_gc();
policy->record_alloc_failure_to_full();
mode = stw_full;
}
-
- } else if (explicit_gc_requested) {
+ } else if (is_gc_requested) {
cause = requested_gc_cause;
- log_info(gc)("Trigger: Explicit GC request (%s)", GCCause::to_string(cause));
-
+ heuristics->log_trigger("GC request (%s)", GCCause::to_string(cause));
heuristics->record_requested_gc();
- if (ExplicitGCInvokesConcurrent) {
- policy->record_explicit_to_concurrent();
- mode = default_mode;
- // Unload and clean up everything
- heap->set_unload_classes(heuristics->can_unload_classes());
- } else {
- policy->record_explicit_to_full();
+ if (ShenandoahCollectorPolicy::should_run_full_gc(cause)) {
mode = stw_full;
- }
- } else if (implicit_gc_requested) {
- cause = requested_gc_cause;
- log_info(gc)("Trigger: Implicit GC request (%s)", GCCause::to_string(cause));
-
- heuristics->record_requested_gc();
-
- if (ShenandoahImplicitGCInvokesConcurrent) {
- policy->record_implicit_to_concurrent();
+ } else {
mode = default_mode;
-
// Unload and clean up everything
heap->set_unload_classes(heuristics->can_unload_classes());
- } else {
- policy->record_implicit_to_full();
- mode = stw_full;
}
} else {
// Potential normal cycle: ask heuristics if it wants to act
if (heuristics->should_start_gc()) {
mode = default_mode;
heap->set_unload_classes(heuristics->should_unload_classes());
}
// Blow all soft references on this cycle, if handling allocation failure,
// either implicit or explicit GC request, or we are requested to do so unconditionally.
- if (alloc_failure_pending || implicit_gc_requested || explicit_gc_requested || ShenandoahAlwaysClearSoftRefs) {
+ if (alloc_failure_pending || is_gc_requested || ShenandoahAlwaysClearSoftRefs) {
heap->soft_ref_policy()->set_should_clear_all_soft_refs(true);
}
- bool gc_requested = (mode != none);
+ const bool gc_requested = (mode != none);
assert (!gc_requested || cause != GCCause::_last_gc_cause, "GC cause should be set");
if (gc_requested) {
// GC is starting, bump the internal ID
update_gc_id();
MetaspaceCombinedStats meta_sizes = MetaspaceUtils::get_combined_statistics();
// If GC was requested, we are sampling the counters even without actual triggers
// from allocation machinery. This captures GC phases more accurately.
- set_forced_counters_update(true);
+ heap->set_forced_counters_update(true);
// If GC was requested, we better dump freeset data for performance debugging
- {
- ShenandoahHeapLocker locker(heap->lock());
- heap->free_set()->log_status();
- }
+ heap->free_set()->log_status_under_lock();
switch (mode) {
case concurrent_normal:
service_concurrent_normal_cycle(cause);
break;
default:
ShouldNotReachHere();
}
// If this was the requested GC cycle, notify waiters about it
- if (explicit_gc_requested || implicit_gc_requested) {
+ if (is_gc_requested) {
notify_gc_waiters();
}
// If this was the allocation failure GC cycle, notify waiters about it
if (alloc_failure_pending) {
notify_alloc_failure_waiters();
}
// Report current free set state at the end of cycle, whether
// it is a normal completion, or the abort.
- {
- ShenandoahHeapLocker locker(heap->lock());
- heap->free_set()->log_status();
+ heap->free_set()->log_status_under_lock();
+ {
// Notify Universe about new heap usage. This has implications for
// global soft refs policy, and we better report it every time heap
// usage goes down.
- Universe::heap()->update_capacity_and_used_at_gc();
-
- // Signal that we have completed a visit to all live objects.
- Universe::heap()->record_whole_heap_examined_timestamp();
+ ShenandoahHeapLocker locker(heap->lock());
+ heap->update_capacity_and_used_at_gc();
}
+ // Signal that we have completed a visit to all live objects.
+ heap->record_whole_heap_examined_timestamp();
+
// Disable forced counters update, and update counters one more time
// to capture the state at the end of GC session.
- handle_force_counters_update();
- set_forced_counters_update(false);
+ heap->handle_force_counters_update();
+ heap->set_forced_counters_update(false);
// Retract forceful part of soft refs policy
heap->soft_ref_policy()->set_should_clear_all_soft_refs(false);
// Clear metaspace oom flag, if current cycle unloaded classes
// GC is over, we are at idle now
if (ShenandoahPacing) {
heap->pacer()->setup_for_idle();
}
} else {
- // Allow allocators to know we have seen this much regions
+ // Report to pacer that we have seen this many words allocated
if (ShenandoahPacing && (allocs_seen > 0)) {
heap->pacer()->report_alloc(allocs_seen);
}
}
- double current = os::elapsedTime();
+ const double current = os::elapsedTime();
- if (ShenandoahUncommit && (explicit_gc_requested || soft_max_changed || (current - last_shrink_time > shrink_period))) {
+ if (ShenandoahUncommit && (is_gc_requested || soft_max_changed || (current - last_shrink_time > shrink_period))) {
// Explicit GC tries to uncommit everything down to min capacity.
// Soft max change tries to uncommit everything down to target capacity.
// Periodic uncommit tries to uncommit suitable regions down to min capacity.
- double shrink_before = (explicit_gc_requested || soft_max_changed) ?
+ double shrink_before = (is_gc_requested || soft_max_changed) ?
current :
current - (ShenandoahUncommitDelay / 1000.0);
size_t shrink_until = soft_max_changed ?
heap->soft_max_capacity() :
heap->min_capacity();
- service_uncommit(shrink_before, shrink_until);
+ heap->maybe_uncommit(shrink_before, shrink_until);
heap->phase_timings()->flush_cycle_to_global();
last_shrink_time = current;
}
// Wait before performing the next action. If allocation happened during this wait,
// we exit sooner, to let heuristics re-evaluate new conditions. If we are at idle,
// back off exponentially.
- if (_heap_changed.try_unset()) {
+ if (heap->has_changed()) {
sleep = ShenandoahControlIntervalMin;
} else if ((current - last_sleep_adjust_time) * 1000 > ShenandoahControlIntervalAdjustPeriod){
sleep = MIN2<int>(ShenandoahControlIntervalMax, MAX2(1, sleep * 2));
last_sleep_adjust_time = current;
}
while (!should_terminate()) {
os::naked_short_sleep(ShenandoahControlIntervalMin);
}
}
- bool ShenandoahControlThread::check_soft_max_changed() const {
- ShenandoahHeap* heap = ShenandoahHeap::heap();
- size_t new_soft_max = Atomic::load(&SoftMaxHeapSize);
- size_t old_soft_max = heap->soft_max_capacity();
- if (new_soft_max != old_soft_max) {
- new_soft_max = MAX2(heap->min_capacity(), new_soft_max);
- new_soft_max = MIN2(heap->max_capacity(), new_soft_max);
- if (new_soft_max != old_soft_max) {
- log_info(gc)("Soft Max Heap Size: " SIZE_FORMAT "%s -> " SIZE_FORMAT "%s",
- byte_size_in_proper_unit(old_soft_max), proper_unit_for_byte_size(old_soft_max),
- byte_size_in_proper_unit(new_soft_max), proper_unit_for_byte_size(new_soft_max)
- );
- heap->set_soft_max_capacity(new_soft_max);
- return true;
- }
- }
- return false;
- }
-
void ShenandoahControlThread::service_concurrent_normal_cycle(GCCause::Cause cause) {
// Normal cycle goes via all concurrent phases. If allocation failure (af) happens during
// any of the concurrent phases, it first degrades to Degenerated GC and completes GC there.
// If second allocation failure happens during Degenerated GC cycle (for example, when GC
// tries to evac something and no memory is available), cycle degrades to Full GC.
//
ShenandoahHeap* heap = ShenandoahHeap::heap();
if (check_cancellation_or_degen(ShenandoahGC::_degenerated_outside_cycle)) return;
GCIdMark gc_id_mark;
- ShenandoahGCSession session(cause);
+ ShenandoahGCSession session(cause, heap->global_generation());
TraceCollectorStats tcs(heap->monitoring_support()->concurrent_collection_counters());
- ShenandoahConcurrentGC gc;
+ ShenandoahConcurrentGC gc(heap->global_generation(), false);
if (gc.collect(cause)) {
- // Cycle is complete
- heap->heuristics()->record_success_concurrent();
- heap->shenandoah_policy()->record_success_concurrent();
+ // Cycle is complete. There were no failed allocation requests and no degeneration, so count this as good progress.
+ heap->notify_gc_progress();
+ heap->global_generation()->heuristics()->record_success_concurrent();
+ heap->shenandoah_policy()->record_success_concurrent(false, gc.abbreviated());
+ heap->log_heap_status("At end of GC");
} else {
assert(heap->cancelled_gc(), "Must have been cancelled");
check_cancellation_or_degen(gc.degen_point());
+ heap->log_heap_status("At end of cancelled GC");
}
}
bool ShenandoahControlThread::check_cancellation_or_degen(ShenandoahGC::ShenandoahDegenPoint point) {
ShenandoahHeap* heap = ShenandoahHeap::heap();
void ShenandoahControlThread::stop_service() {
// Nothing to do here.
}
void ShenandoahControlThread::service_stw_full_cycle(GCCause::Cause cause) {
+ ShenandoahHeap* const heap = ShenandoahHeap::heap();
GCIdMark gc_id_mark;
- ShenandoahGCSession session(cause);
+ ShenandoahGCSession session(cause, heap->global_generation());
ShenandoahFullGC gc;
gc.collect(cause);
-
- ShenandoahHeap* const heap = ShenandoahHeap::heap();
- heap->heuristics()->record_success_full();
- heap->shenandoah_policy()->record_success_full();
}
void ShenandoahControlThread::service_stw_degenerated_cycle(GCCause::Cause cause, ShenandoahGC::ShenandoahDegenPoint point) {
assert (point != ShenandoahGC::_degenerated_unset, "Degenerated point should be set");
-
+ ShenandoahHeap* const heap = ShenandoahHeap::heap();
GCIdMark gc_id_mark;
- ShenandoahGCSession session(cause);
+ ShenandoahGCSession session(cause, heap->global_generation());
- ShenandoahDegenGC gc(point);
+ ShenandoahDegenGC gc(point, heap->global_generation());
gc.collect(cause);
-
- ShenandoahHeap* const heap = ShenandoahHeap::heap();
- heap->heuristics()->record_success_degenerated();
- heap->shenandoah_policy()->record_success_degenerated();
- }
-
- void ShenandoahControlThread::service_uncommit(double shrink_before, size_t shrink_until) {
- ShenandoahHeap* heap = ShenandoahHeap::heap();
-
- // Determine if there is work to do. This avoids taking heap lock if there is
- // no work available, avoids spamming logs with superfluous logging messages,
- // and minimises the amount of work while locks are taken.
-
- if (heap->committed() <= shrink_until) return;
-
- bool has_work = false;
- for (size_t i = 0; i < heap->num_regions(); i++) {
- ShenandoahHeapRegion *r = heap->get_region(i);
- if (r->is_empty_committed() && (r->empty_time() < shrink_before)) {
- has_work = true;
- break;
- }
- }
-
- if (has_work) {
- heap->entry_uncommit(shrink_before, shrink_until);
- }
- }
-
- bool ShenandoahControlThread::is_explicit_gc(GCCause::Cause cause) const {
- return GCCause::is_user_requested_gc(cause) ||
- GCCause::is_serviceability_requested_gc(cause);
}
void ShenandoahControlThread::request_gc(GCCause::Cause cause) {
- assert(GCCause::is_user_requested_gc(cause) ||
- GCCause::is_serviceability_requested_gc(cause) ||
- cause == GCCause::_metadata_GC_clear_soft_refs ||
- cause == GCCause::_codecache_GC_aggressive ||
- cause == GCCause::_codecache_GC_threshold ||
- cause == GCCause::_full_gc_alot ||
- cause == GCCause::_wb_young_gc ||
- cause == GCCause::_wb_full_gc ||
- cause == GCCause::_wb_breakpoint ||
- cause == GCCause::_scavenge_alot,
- "only requested GCs here: %s", GCCause::to_string(cause));
-
- if (is_explicit_gc(cause)) {
- if (!DisableExplicitGC) {
- handle_requested_gc(cause);
- }
- } else {
+ if (ShenandoahCollectorPolicy::should_handle_requested_gc(cause)) {
handle_requested_gc(cause);
}
}
void ShenandoahControlThread::handle_requested_gc(GCCause::Cause cause) {
+ // For normal requested GCs (System.gc) we want to block the caller. However,
+ // for whitebox requested GC, we want to initiate the GC and return immediately.
+ // The whitebox caller thread will arrange for itself to wait until the GC notifies
+ // it that has reached the requested breakpoint (phase in the GC).
+ if (cause == GCCause::_wb_breakpoint) {
+ _requested_gc_cause = cause;
+ _gc_requested.set();
+ return;
+ }
+
// Make sure we have at least one complete GC cycle before unblocking
// from the explicit GC request.
//
// This is especially important for weak references cleanup and/or native
// resources (e.g. DirectByteBuffers) machinery: when explicit GC request
// does not take the lock. We need to enforce following order, so that read side sees
// latest requested gc cause when the flag is set.
_requested_gc_cause = cause;
_gc_requested.set();
- if (cause != GCCause::_wb_breakpoint) {
- ml.wait();
- }
- current_gc_id = get_gc_id();
- }
- }
-
- void ShenandoahControlThread::handle_alloc_failure(ShenandoahAllocRequest& req) {
- ShenandoahHeap* heap = ShenandoahHeap::heap();
-
- assert(current()->is_Java_thread(), "expect Java thread here");
-
- if (try_set_alloc_failure_gc()) {
- // Only report the first allocation failure
- log_info(gc)("Failed to allocate %s, " SIZE_FORMAT "%s",
- req.type_string(),
- byte_size_in_proper_unit(req.size() * HeapWordSize), proper_unit_for_byte_size(req.size() * HeapWordSize));
-
- // Now that alloc failure GC is scheduled, we can abort everything else
- heap->cancel_gc(GCCause::_allocation_failure);
- }
-
- MonitorLocker ml(&_alloc_failure_waiters_lock);
- while (is_alloc_failure_gc()) {
ml.wait();
+ current_gc_id = get_gc_id();
}
}
- void ShenandoahControlThread::handle_alloc_failure_evac(size_t words) {
- ShenandoahHeap* heap = ShenandoahHeap::heap();
-
- if (try_set_alloc_failure_gc()) {
- // Only report the first allocation failure
- log_info(gc)("Failed to allocate " SIZE_FORMAT "%s for evacuation",
- byte_size_in_proper_unit(words * HeapWordSize), proper_unit_for_byte_size(words * HeapWordSize));
- }
-
- // Forcefully report allocation failure
- heap->cancel_gc(GCCause::_shenandoah_allocation_failure_evac);
- }
-
- void ShenandoahControlThread::notify_alloc_failure_waiters() {
- _alloc_failure_gc.unset();
- MonitorLocker ml(&_alloc_failure_waiters_lock);
- ml.notify_all();
- }
-
- bool ShenandoahControlThread::try_set_alloc_failure_gc() {
- return _alloc_failure_gc.try_set();
- }
-
- bool ShenandoahControlThread::is_alloc_failure_gc() {
- return _alloc_failure_gc.is_set();
- }
-
void ShenandoahControlThread::notify_gc_waiters() {
_gc_requested.unset();
MonitorLocker ml(&_gc_waiters_lock);
ml.notify_all();
}
-
- void ShenandoahControlThread::handle_counters_update() {
- if (_do_counters_update.is_set()) {
- _do_counters_update.unset();
- ShenandoahHeap::heap()->monitoring_support()->update_counters();
- }
- }
-
- void ShenandoahControlThread::handle_force_counters_update() {
- if (_force_counters_update.is_set()) {
- _do_counters_update.unset(); // reset these too, we do update now!
- ShenandoahHeap::heap()->monitoring_support()->update_counters();
- }
- }
-
- void ShenandoahControlThread::notify_heap_changed() {
- // This is called from allocation path, and thus should be fast.
-
- // Update monitoring counters when we took a new region. This amortizes the
- // update costs on slow path.
- if (_do_counters_update.is_unset()) {
- _do_counters_update.set();
- }
- // Notify that something had changed.
- if (_heap_changed.is_unset()) {
- _heap_changed.set();
- }
- }
-
- void ShenandoahControlThread::pacing_notify_alloc(size_t words) {
- assert(ShenandoahPacing, "should only call when pacing is enabled");
- Atomic::add(&_allocs_seen, words, memory_order_relaxed);
- }
-
- void ShenandoahControlThread::set_forced_counters_update(bool value) {
- _force_counters_update.set_cond(value);
- }
-
- void ShenandoahControlThread::reset_gc_id() {
- Atomic::store(&_gc_id, (size_t)0);
- }
-
- void ShenandoahControlThread::update_gc_id() {
- Atomic::inc(&_gc_id);
- }
-
- size_t ShenandoahControlThread::get_gc_id() {
- return Atomic::load(&_gc_id);
- }
-
- void ShenandoahControlThread::start() {
- create_and_start();
- }
-
- void ShenandoahControlThread::prepare_for_graceful_shutdown() {
- _graceful_shutdown.set();
- }
-
- bool ShenandoahControlThread::in_graceful_shutdown() {
- return _graceful_shutdown.is_set();
- }
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