--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/src/hotspot/share/gc/parallel/gcTaskManager.hpp Tue Sep 12 19:03:39 2017 +0200
@@ -0,0 +1,668 @@
+/*
+ * Copyright (c) 2002, 2016, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ *
+ */
+
+#ifndef SHARE_VM_GC_PARALLEL_GCTASKMANAGER_HPP
+#define SHARE_VM_GC_PARALLEL_GCTASKMANAGER_HPP
+
+#include "runtime/mutex.hpp"
+#include "utilities/growableArray.hpp"
+
+//
+// The GCTaskManager is a queue of GCTasks, and accessors
+// to allow the queue to be accessed from many threads.
+//
+
+// Forward declarations of types defined in this file.
+class GCTask;
+class GCTaskQueue;
+class SynchronizedGCTaskQueue;
+class GCTaskManager;
+// Some useful subclasses of GCTask. You can also make up your own.
+class NoopGCTask;
+class WaitForBarrierGCTask;
+class IdleGCTask;
+// A free list of Monitor*'s.
+class MonitorSupply;
+
+// Forward declarations of classes referenced in this file via pointer.
+class GCTaskThread;
+class Mutex;
+class Monitor;
+class ThreadClosure;
+
+// The abstract base GCTask.
+class GCTask : public ResourceObj {
+public:
+ // Known kinds of GCTasks, for predicates.
+ class Kind : AllStatic {
+ public:
+ enum kind {
+ unknown_task,
+ ordinary_task,
+ wait_for_barrier_task,
+ noop_task,
+ idle_task
+ };
+ static const char* to_string(kind value);
+ };
+private:
+ // Instance state.
+ Kind::kind _kind; // For runtime type checking.
+ uint _affinity; // Which worker should run task.
+ GCTask* _newer; // Tasks are on doubly-linked ...
+ GCTask* _older; // ... lists.
+ uint _gc_id; // GC Id to use for the thread that executes this task
+public:
+ virtual char* name() { return (char *)"task"; }
+
+ uint gc_id() { return _gc_id; }
+
+ // Abstract do_it method
+ virtual void do_it(GCTaskManager* manager, uint which) = 0;
+ // Accessors
+ Kind::kind kind() const {
+ return _kind;
+ }
+ uint affinity() const {
+ return _affinity;
+ }
+ GCTask* newer() const {
+ return _newer;
+ }
+ void set_newer(GCTask* n) {
+ _newer = n;
+ }
+ GCTask* older() const {
+ return _older;
+ }
+ void set_older(GCTask* p) {
+ _older = p;
+ }
+ // Predicates.
+ bool is_ordinary_task() const {
+ return kind()==Kind::ordinary_task;
+ }
+ bool is_barrier_task() const {
+ return kind()==Kind::wait_for_barrier_task;
+ }
+ bool is_noop_task() const {
+ return kind()==Kind::noop_task;
+ }
+ bool is_idle_task() const {
+ return kind()==Kind::idle_task;
+ }
+ void print(const char* message) const PRODUCT_RETURN;
+protected:
+ // Constructors: Only create subclasses.
+ // An ordinary GCTask.
+ GCTask();
+ // A GCTask of a particular kind, usually barrier or noop.
+ GCTask(Kind::kind kind);
+ GCTask(Kind::kind kind, uint gc_id);
+ // We want a virtual destructor because virtual methods,
+ // but since ResourceObj's don't have their destructors
+ // called, we don't have one at all. Instead we have
+ // this method, which gets called by subclasses to clean up.
+ virtual void destruct();
+ // Methods.
+ void initialize(Kind::kind kind, uint gc_id);
+};
+
+// A doubly-linked list of GCTasks.
+// The list is not synchronized, because sometimes we want to
+// build up a list and then make it available to other threads.
+// See also: SynchronizedGCTaskQueue.
+class GCTaskQueue : public ResourceObj {
+private:
+ // Instance state.
+ GCTask* _insert_end; // Tasks are enqueued at this end.
+ GCTask* _remove_end; // Tasks are dequeued from this end.
+ uint _length; // The current length of the queue.
+ const bool _is_c_heap_obj; // Is this a CHeapObj?
+public:
+ // Factory create and destroy methods.
+ // Create as ResourceObj.
+ static GCTaskQueue* create();
+ // Create as CHeapObj.
+ static GCTaskQueue* create_on_c_heap();
+ // Destroyer.
+ static void destroy(GCTaskQueue* that);
+ // Accessors.
+ // These just examine the state of the queue.
+ bool is_empty() const {
+ assert(((insert_end() == NULL && remove_end() == NULL) ||
+ (insert_end() != NULL && remove_end() != NULL)),
+ "insert_end and remove_end don't match");
+ assert((insert_end() != NULL) || (_length == 0), "Not empty");
+ return insert_end() == NULL;
+ }
+ uint length() const {
+ return _length;
+ }
+ // Methods.
+ // Enqueue one task.
+ void enqueue(GCTask* task);
+ // Enqueue a list of tasks. Empties the argument list.
+ void enqueue(GCTaskQueue* list);
+ // Dequeue one task.
+ GCTask* dequeue();
+ // Dequeue one task, preferring one with affinity.
+ GCTask* dequeue(uint affinity);
+protected:
+ // Constructor. Clients use factory, but there might be subclasses.
+ GCTaskQueue(bool on_c_heap);
+ // Destructor-like method.
+ // Because ResourceMark doesn't call destructors.
+ // This method cleans up like one.
+ virtual void destruct();
+ // Accessors.
+ GCTask* insert_end() const {
+ return _insert_end;
+ }
+ void set_insert_end(GCTask* value) {
+ _insert_end = value;
+ }
+ GCTask* remove_end() const {
+ return _remove_end;
+ }
+ void set_remove_end(GCTask* value) {
+ _remove_end = value;
+ }
+ void increment_length() {
+ _length += 1;
+ }
+ void decrement_length() {
+ _length -= 1;
+ }
+ void set_length(uint value) {
+ _length = value;
+ }
+ bool is_c_heap_obj() const {
+ return _is_c_heap_obj;
+ }
+ // Methods.
+ void initialize();
+ GCTask* remove(); // Remove from remove end.
+ GCTask* remove(GCTask* task); // Remove from the middle.
+ void print(const char* message) const PRODUCT_RETURN;
+ // Debug support
+ void verify_length() const PRODUCT_RETURN;
+};
+
+// A GCTaskQueue that can be synchronized.
+// This "has-a" GCTaskQueue and a mutex to do the exclusion.
+class SynchronizedGCTaskQueue : public CHeapObj<mtGC> {
+private:
+ // Instance state.
+ GCTaskQueue* _unsynchronized_queue; // Has-a unsynchronized queue.
+ Monitor * _lock; // Lock to control access.
+public:
+ // Factory create and destroy methods.
+ static SynchronizedGCTaskQueue* create(GCTaskQueue* queue, Monitor * lock) {
+ return new SynchronizedGCTaskQueue(queue, lock);
+ }
+ static void destroy(SynchronizedGCTaskQueue* that) {
+ if (that != NULL) {
+ delete that;
+ }
+ }
+ // Accessors
+ GCTaskQueue* unsynchronized_queue() const {
+ return _unsynchronized_queue;
+ }
+ Monitor * lock() const {
+ return _lock;
+ }
+ // GCTaskQueue wrapper methods.
+ // These check that you hold the lock
+ // and then call the method on the queue.
+ bool is_empty() const {
+ guarantee(own_lock(), "don't own the lock");
+ return unsynchronized_queue()->is_empty();
+ }
+ void enqueue(GCTask* task) {
+ guarantee(own_lock(), "don't own the lock");
+ unsynchronized_queue()->enqueue(task);
+ }
+ void enqueue(GCTaskQueue* list) {
+ guarantee(own_lock(), "don't own the lock");
+ unsynchronized_queue()->enqueue(list);
+ }
+ GCTask* dequeue() {
+ guarantee(own_lock(), "don't own the lock");
+ return unsynchronized_queue()->dequeue();
+ }
+ GCTask* dequeue(uint affinity) {
+ guarantee(own_lock(), "don't own the lock");
+ return unsynchronized_queue()->dequeue(affinity);
+ }
+ uint length() const {
+ guarantee(own_lock(), "don't own the lock");
+ return unsynchronized_queue()->length();
+ }
+ // For guarantees.
+ bool own_lock() const {
+ return lock()->owned_by_self();
+ }
+protected:
+ // Constructor. Clients use factory, but there might be subclasses.
+ SynchronizedGCTaskQueue(GCTaskQueue* queue, Monitor * lock);
+ // Destructor. Not virtual because no virtuals.
+ ~SynchronizedGCTaskQueue();
+};
+
+class WaitHelper VALUE_OBJ_CLASS_SPEC {
+ private:
+ Monitor* _monitor;
+ volatile bool _should_wait;
+ public:
+ WaitHelper();
+ ~WaitHelper();
+ void wait_for(bool reset);
+ void notify();
+ void set_should_wait(bool value) {
+ _should_wait = value;
+ }
+
+ Monitor* monitor() const {
+ return _monitor;
+ }
+ bool should_wait() const {
+ return _should_wait;
+ }
+ void release_monitor();
+};
+
+// Dynamic number of GC threads
+//
+// GC threads wait in get_task() for work (i.e., a task) to perform.
+// When the number of GC threads was static, the number of tasks
+// created to do a job was equal to or greater than the maximum
+// number of GC threads (ParallelGCThreads). The job might be divided
+// into a number of tasks greater than the number of GC threads for
+// load balancing (i.e., over partitioning). The last task to be
+// executed by a GC thread in a job is a work stealing task. A
+// GC thread that gets a work stealing task continues to execute
+// that task until the job is done. In the static number of GC threads
+// case, tasks are added to a queue (FIFO). The work stealing tasks are
+// the last to be added. Once the tasks are added, the GC threads grab
+// a task and go. A single thread can do all the non-work stealing tasks
+// and then execute a work stealing and wait for all the other GC threads
+// to execute their work stealing task.
+// In the dynamic number of GC threads implementation, idle-tasks are
+// created to occupy the non-participating or "inactive" threads. An
+// idle-task makes the GC thread wait on a barrier that is part of the
+// GCTaskManager. The GC threads that have been "idled" in a IdleGCTask
+// are released once all the active GC threads have finished their work
+// stealing tasks. The GCTaskManager does not wait for all the "idled"
+// GC threads to resume execution. When those GC threads do resume
+// execution in the course of the thread scheduling, they call get_tasks()
+// as all the other GC threads do. Because all the "idled" threads are
+// not required to execute in order to finish a job, it is possible for
+// a GC thread to still be "idled" when the next job is started. Such
+// a thread stays "idled" for the next job. This can result in a new
+// job not having all the expected active workers. For example if on
+// job requests 4 active workers out of a total of 10 workers so the
+// remaining 6 are "idled", if the next job requests 6 active workers
+// but all 6 of the "idled" workers are still idle, then the next job
+// will only get 4 active workers.
+// The implementation for the parallel old compaction phase has an
+// added complication. In the static case parold partitions the chunks
+// ready to be filled into stacks, one for each GC thread. A GC thread
+// executing a draining task (drains the stack of ready chunks)
+// claims a stack according to it's id (the unique ordinal value assigned
+// to each GC thread). In the dynamic case not all GC threads will
+// actively participate so stacks with ready to fill chunks can only be
+// given to the active threads. An initial implementation chose stacks
+// number 1-n to get the ready chunks and required that GC threads
+// 1-n be the active workers. This was undesirable because it required
+// certain threads to participate. In the final implementation a
+// list of stacks equal in number to the active workers are filled
+// with ready chunks. GC threads that participate get a stack from
+// the task (DrainStacksCompactionTask), empty the stack, and then add it to a
+// recycling list at the end of the task. If the same GC thread gets
+// a second task, it gets a second stack to drain and returns it. The
+// stacks are added to a recycling list so that later stealing tasks
+// for this tasks can get a stack from the recycling list. Stealing tasks
+// use the stacks in its work in a way similar to the draining tasks.
+// A thread is not guaranteed to get anything but a stealing task and
+// a thread that only gets a stealing task has to get a stack. A failed
+// implementation tried to have the GC threads keep the stack they used
+// during a draining task for later use in the stealing task but that didn't
+// work because as noted a thread is not guaranteed to get a draining task.
+//
+// For PSScavenge and ParCompactionManager the GC threads are
+// held in the GCTaskThread** _thread array in GCTaskManager.
+
+
+class GCTaskManager : public CHeapObj<mtGC> {
+ friend class ParCompactionManager;
+ friend class PSParallelCompact;
+ friend class PSScavenge;
+ friend class PSRefProcTaskExecutor;
+ friend class RefProcTaskExecutor;
+ friend class GCTaskThread;
+ friend class IdleGCTask;
+private:
+ // Instance state.
+ const uint _workers; // Number of workers.
+ Monitor* _monitor; // Notification of changes.
+ SynchronizedGCTaskQueue* _queue; // Queue of tasks.
+ GCTaskThread** _thread; // Array of worker threads.
+ uint _created_workers; // Number of workers created.
+ uint _active_workers; // Number of active workers.
+ uint _busy_workers; // Number of busy workers.
+ uint _blocking_worker; // The worker that's blocking.
+ bool* _resource_flag; // Array of flag per threads.
+ uint _delivered_tasks; // Count of delivered tasks.
+ uint _completed_tasks; // Count of completed tasks.
+ uint _barriers; // Count of barrier tasks.
+ uint _emptied_queue; // Times we emptied the queue.
+ NoopGCTask* _noop_task; // The NoopGCTask instance.
+ WaitHelper _wait_helper; // Used by inactive worker
+ volatile uint _idle_workers; // Number of idled workers
+ uint* _processor_assignment; // Worker to cpu mappings. May
+ // be used lazily
+public:
+ // Factory create and destroy methods.
+ static GCTaskManager* create(uint workers) {
+ return new GCTaskManager(workers);
+ }
+ static void destroy(GCTaskManager* that) {
+ if (that != NULL) {
+ delete that;
+ }
+ }
+ // Accessors.
+ uint busy_workers() const {
+ return _busy_workers;
+ }
+ volatile uint idle_workers() const {
+ return _idle_workers;
+ }
+ // Pun between Monitor* and Mutex*
+ Monitor* monitor() const {
+ return _monitor;
+ }
+ Monitor * lock() const {
+ return _monitor;
+ }
+ WaitHelper* wait_helper() {
+ return &_wait_helper;
+ }
+ // Methods.
+ // Add the argument task to be run.
+ void add_task(GCTask* task);
+ // Add a list of tasks. Removes task from the argument list.
+ void add_list(GCTaskQueue* list);
+ // Claim a task for argument worker.
+ GCTask* get_task(uint which);
+ // Note the completion of a task by the argument worker.
+ void note_completion(uint which);
+ // Is the queue blocked from handing out new tasks?
+ bool is_blocked() const {
+ return (blocking_worker() != sentinel_worker());
+ }
+ // Request that all workers release their resources.
+ void release_all_resources();
+ // Ask if a particular worker should release its resources.
+ bool should_release_resources(uint which); // Predicate.
+ // Note the release of resources by the argument worker.
+ void note_release(uint which);
+ // Create IdleGCTasks for inactive workers and start workers
+ void task_idle_workers();
+ // Release the workers in IdleGCTasks
+ void release_idle_workers();
+ // Constants.
+ // A sentinel worker identifier.
+ static uint sentinel_worker() {
+ return (uint) -1; // Why isn't there a max_uint?
+ }
+
+ // Execute the task queue and wait for the completion.
+ void execute_and_wait(GCTaskQueue* list);
+
+ void print_task_time_stamps();
+ void print_threads_on(outputStream* st);
+ void threads_do(ThreadClosure* tc);
+
+protected:
+ // Constructors. Clients use factory, but there might be subclasses.
+ // Create a GCTaskManager with the appropriate number of workers.
+ GCTaskManager(uint workers);
+ // Make virtual if necessary.
+ ~GCTaskManager();
+ // Accessors.
+ uint workers() const {
+ return _workers;
+ }
+ uint update_active_workers(uint v) {
+ assert(v <= _workers, "Trying to set more workers active than there are");
+ _active_workers = MIN2(v, _workers);
+ assert(v != 0, "Trying to set active workers to 0");
+ _active_workers = MAX2(1U, _active_workers);
+ return _active_workers;
+ }
+ // Sets the number of threads that will be used in a collection
+ void set_active_gang();
+
+ SynchronizedGCTaskQueue* queue() const {
+ return _queue;
+ }
+ NoopGCTask* noop_task() const {
+ return _noop_task;
+ }
+ // Bounds-checking per-thread data accessors.
+ GCTaskThread* thread(uint which);
+ void set_thread(uint which, GCTaskThread* value);
+ bool resource_flag(uint which);
+ void set_resource_flag(uint which, bool value);
+ // Modifier methods with some semantics.
+ // Is any worker blocking handing out new tasks?
+ uint blocking_worker() const {
+ return _blocking_worker;
+ }
+ void set_blocking_worker(uint value) {
+ _blocking_worker = value;
+ }
+ void set_unblocked() {
+ set_blocking_worker(sentinel_worker());
+ }
+ // Count of busy workers.
+ void reset_busy_workers() {
+ _busy_workers = 0;
+ }
+ uint increment_busy_workers();
+ uint decrement_busy_workers();
+ // Count of tasks delivered to workers.
+ uint delivered_tasks() const {
+ return _delivered_tasks;
+ }
+ void increment_delivered_tasks() {
+ _delivered_tasks += 1;
+ }
+ void reset_delivered_tasks() {
+ _delivered_tasks = 0;
+ }
+ // Count of tasks completed by workers.
+ uint completed_tasks() const {
+ return _completed_tasks;
+ }
+ void increment_completed_tasks() {
+ _completed_tasks += 1;
+ }
+ void reset_completed_tasks() {
+ _completed_tasks = 0;
+ }
+ // Count of barrier tasks completed.
+ uint barriers() const {
+ return _barriers;
+ }
+ void increment_barriers() {
+ _barriers += 1;
+ }
+ void reset_barriers() {
+ _barriers = 0;
+ }
+ // Count of how many times the queue has emptied.
+ uint emptied_queue() const {
+ return _emptied_queue;
+ }
+ void increment_emptied_queue() {
+ _emptied_queue += 1;
+ }
+ void reset_emptied_queue() {
+ _emptied_queue = 0;
+ }
+ void increment_idle_workers() {
+ _idle_workers++;
+ }
+ void decrement_idle_workers() {
+ _idle_workers--;
+ }
+ // Other methods.
+ void initialize();
+
+ public:
+ // Return true if all workers are currently active.
+ bool all_workers_active() { return workers() == active_workers(); }
+ uint active_workers() const {
+ return _active_workers;
+ }
+ uint created_workers() const {
+ return _created_workers;
+ }
+ // Create a GC worker and install into GCTaskManager
+ GCTaskThread* install_worker(uint worker_id);
+ // Add GC workers as needed.
+ void add_workers(bool initializing);
+ // Base name (without worker id #) of threads.
+ const char* group_name();
+};
+
+//
+// Some exemplary GCTasks.
+//
+
+// A noop task that does nothing,
+// except take us around the GCTaskThread loop.
+class NoopGCTask : public GCTask {
+public:
+ // Factory create and destroy methods.
+ static NoopGCTask* create_on_c_heap();
+ static void destroy(NoopGCTask* that);
+
+ virtual char* name() { return (char *)"noop task"; }
+ // Methods from GCTask.
+ void do_it(GCTaskManager* manager, uint which) {
+ // Nothing to do.
+ }
+protected:
+ // Constructor.
+ NoopGCTask();
+ // Destructor-like method.
+ void destruct();
+};
+
+// A WaitForBarrierGCTask is a GCTask
+// with a method you can call to wait until
+// the BarrierGCTask is done.
+class WaitForBarrierGCTask : public GCTask {
+ friend class GCTaskManager;
+ friend class IdleGCTask;
+private:
+ // Instance state.
+ WaitHelper _wait_helper;
+ WaitForBarrierGCTask();
+public:
+ virtual char* name() { return (char *) "waitfor-barrier-task"; }
+
+ // Factory create and destroy methods.
+ static WaitForBarrierGCTask* create();
+ static void destroy(WaitForBarrierGCTask* that);
+ // Methods.
+ void do_it(GCTaskManager* manager, uint which);
+protected:
+ // Destructor-like method.
+ void destruct();
+
+ // Methods.
+ // Wait for this to be the only task running.
+ void do_it_internal(GCTaskManager* manager, uint which);
+
+ void wait_for(bool reset) {
+ _wait_helper.wait_for(reset);
+ }
+};
+
+// Task that is used to idle a GC task when fewer than
+// the maximum workers are wanted.
+class IdleGCTask : public GCTask {
+ const bool _is_c_heap_obj; // Was allocated on the heap.
+ public:
+ bool is_c_heap_obj() {
+ return _is_c_heap_obj;
+ }
+ // Factory create and destroy methods.
+ static IdleGCTask* create();
+ static IdleGCTask* create_on_c_heap();
+ static void destroy(IdleGCTask* that);
+
+ virtual char* name() { return (char *)"idle task"; }
+ // Methods from GCTask.
+ virtual void do_it(GCTaskManager* manager, uint which);
+protected:
+ // Constructor.
+ IdleGCTask(bool on_c_heap) :
+ GCTask(GCTask::Kind::idle_task),
+ _is_c_heap_obj(on_c_heap) {
+ // Nothing to do.
+ }
+ // Destructor-like method.
+ void destruct();
+};
+
+class MonitorSupply : public AllStatic {
+private:
+ // State.
+ // Control multi-threaded access.
+ static Mutex* _lock;
+ // The list of available Monitor*'s.
+ static GrowableArray<Monitor*>* _freelist;
+public:
+ // Reserve a Monitor*.
+ static Monitor* reserve();
+ // Release a Monitor*.
+ static void release(Monitor* instance);
+private:
+ // Accessors.
+ static Mutex* lock() {
+ return _lock;
+ }
+ static GrowableArray<Monitor*>* freelist() {
+ return _freelist;
+ }
+};
+
+#endif // SHARE_VM_GC_PARALLEL_GCTASKMANAGER_HPP