1 /*
2 * Copyright (c) 2002, 2011, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
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15 * You should have received a copy of the GNU General Public License version
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24
25 #ifndef SHARE_VM_UTILITIES_WORKGROUP_HPP
26 #define SHARE_VM_UTILITIES_WORKGROUP_HPP
27
28 #include "utilities/taskqueue.hpp"
29 #ifdef TARGET_OS_FAMILY_linux
30 # include "thread_linux.inline.hpp"
31 #endif
32 #ifdef TARGET_OS_FAMILY_solaris
33 # include "thread_solaris.inline.hpp"
34 #endif
35 #ifdef TARGET_OS_FAMILY_windows
36 # include "thread_windows.inline.hpp"
37 #endif
38 #ifdef TARGET_OS_FAMILY_bsd
39 # include "thread_bsd.inline.hpp"
40 #endif
41
42 // Task class hierarchy:
43 // AbstractGangTask
44 // AbstractGangTaskWOopQueues
45 //
46 // Gang/Group class hierarchy:
47 // AbstractWorkGang
48 // WorkGang
49 // FlexibleWorkGang
50 // YieldingFlexibleWorkGang (defined in another file)
51 //
52 // Worker class hierarchy:
53 // GangWorker (subclass of WorkerThread)
54 // YieldingFlexibleGangWorker (defined in another file)
55
56 // Forward declarations of classes defined here
57
58 class WorkGang;
59 class GangWorker;
60 class YieldingFlexibleGangWorker;
61 class YieldingFlexibleGangTask;
62 class WorkData;
63 class AbstractWorkGang;
64
65 // An abstract task to be worked on by a gang.
66 // You subclass this to supply your own work() method
67 class AbstractGangTask VALUE_OBJ_CLASS_SPEC {
68 public:
69 // The abstract work method.
70 // The argument tells you which member of the gang you are.
71 virtual void work(int i) = 0;
72
73 // This method configures the task for proper termination.
74 // Some tasks do not have any requirements on termination
75 // and may inherit this method that does nothing. Some
76 // tasks do some coordination on termination and override
77 // this method to implement that coordination.
78 virtual void set_for_termination(int active_workers) {};
79
80 // Debugging accessor for the name.
81 const char* name() const PRODUCT_RETURN_(return NULL;);
82 int counter() { return _counter; }
83 void set_counter(int value) { _counter = value; }
84 int *address_of_counter() { return &_counter; }
85
86 // RTTI
87 NOT_PRODUCT(virtual bool is_YieldingFlexibleGang_task() const {
88 return false;
89 })
90
91 private:
92 NOT_PRODUCT(const char* _name;)
93 // ??? Should a task have a priority associated with it?
94 // ??? Or can the run method adjust priority as needed?
95 int _counter;
96
97 protected:
98 // Constructor and desctructor: only construct subclasses.
99 AbstractGangTask(const char* name) {
100 NOT_PRODUCT(_name = name);
101 _counter = 0;
102 }
103 virtual ~AbstractGangTask() { }
104 };
105
106 class AbstractGangTaskWOopQueues : public AbstractGangTask {
107 OopTaskQueueSet* _queues;
108 ParallelTaskTerminator _terminator;
109 public:
110 AbstractGangTaskWOopQueues(const char* name, OopTaskQueueSet* queues) :
111 AbstractGangTask(name), _queues(queues), _terminator(0, _queues) {}
112 ParallelTaskTerminator* terminator() { return &_terminator; }
113 virtual void set_for_termination(int active_workers) {
114 terminator()->reset_for_reuse(active_workers);
115 }
116 OopTaskQueueSet* queues() { return _queues; }
117 };
118
119 // Class AbstractWorkGang:
120 // An abstract class representing a gang of workers.
121 // You subclass this to supply an implementation of run_task().
122 class AbstractWorkGang: public CHeapObj {
123 // Here's the public interface to this class.
124 public:
125 // Constructor and destructor.
126 AbstractWorkGang(const char* name, bool are_GC_task_threads,
127 bool are_ConcurrentGC_threads);
128 ~AbstractWorkGang();
129 // Run a task, returns when the task is done (or terminated).
130 virtual void run_task(AbstractGangTask* task) = 0;
131 // Stop and terminate all workers.
132 virtual void stop();
133 public:
134 // Debugging.
135 const char* name() const;
136 protected:
137 // Initialize only instance data.
138 const bool _are_GC_task_threads;
139 const bool _are_ConcurrentGC_threads;
140 // Printing support.
141 const char* _name;
142 // The monitor which protects these data,
143 // and notifies of changes in it.
144 Monitor* _monitor;
145 // The count of the number of workers in the gang.
146 int _total_workers;
147 // Whether the workers should terminate.
148 bool _terminate;
149 // The array of worker threads for this gang.
150 // This is only needed for cleaning up.
151 GangWorker** _gang_workers;
152 // The task for this gang.
153 AbstractGangTask* _task;
154 // A sequence number for the current task.
155 int _sequence_number;
156 // The number of started workers.
157 int _started_workers;
158 // The number of finished workers.
159 int _finished_workers;
160 public:
161 // Accessors for fields
162 Monitor* monitor() const {
163 return _monitor;
164 }
165 int total_workers() const {
166 return _total_workers;
167 }
168 virtual int active_workers() const {
169 return _total_workers;
170 }
171 bool terminate() const {
172 return _terminate;
173 }
174 GangWorker** gang_workers() const {
175 return _gang_workers;
176 }
177 AbstractGangTask* task() const {
178 return _task;
179 }
180 int sequence_number() const {
181 return _sequence_number;
182 }
183 int started_workers() const {
184 return _started_workers;
185 }
186 int finished_workers() const {
187 return _finished_workers;
188 }
189 bool are_GC_task_threads() const {
190 return _are_GC_task_threads;
191 }
192 bool are_ConcurrentGC_threads() const {
193 return _are_ConcurrentGC_threads;
194 }
195 // Predicates.
196 bool is_idle() const {
197 return (task() == NULL);
198 }
199 // Return the Ith gang worker.
200 GangWorker* gang_worker(int i) const;
201
202 void threads_do(ThreadClosure* tc) const;
203
204 // Printing
205 void print_worker_threads_on(outputStream *st) const;
206 void print_worker_threads() const {
207 print_worker_threads_on(tty);
208 }
209
210 protected:
211 friend class GangWorker;
212 friend class YieldingFlexibleGangWorker;
213 // Note activation and deactivation of workers.
214 // These methods should only be called with the mutex held.
215 void internal_worker_poll(WorkData* data) const;
216 void internal_note_start();
217 void internal_note_finish();
218 };
219
220 class WorkData: public StackObj {
221 // This would be a struct, but I want accessor methods.
222 private:
223 bool _terminate;
224 AbstractGangTask* _task;
225 int _sequence_number;
226 public:
227 // Constructor and destructor
228 WorkData() {
229 _terminate = false;
230 _task = NULL;
231 _sequence_number = 0;
232 }
233 ~WorkData() {
234 }
235 // Accessors and modifiers
236 bool terminate() const { return _terminate; }
237 void set_terminate(bool value) { _terminate = value; }
238 AbstractGangTask* task() const { return _task; }
239 void set_task(AbstractGangTask* value) { _task = value; }
240 int sequence_number() const { return _sequence_number; }
241 void set_sequence_number(int value) { _sequence_number = value; }
242
243 YieldingFlexibleGangTask* yf_task() const {
244 return (YieldingFlexibleGangTask*)_task;
245 }
246 };
247
248 // Class WorkGang:
249 class WorkGang: public AbstractWorkGang {
250 public:
251 // Constructor
252 WorkGang(const char* name, int workers,
253 bool are_GC_task_threads, bool are_ConcurrentGC_threads);
254 // Run a task, returns when the task is done (or terminated).
255 virtual void run_task(AbstractGangTask* task);
256 void run_task(AbstractGangTask* task, uint no_of_parallel_workers);
257 // Allocate a worker and return a pointer to it.
258 virtual GangWorker* allocate_worker(int which);
259 // Initialize workers in the gang. Return true if initialization
260 // succeeded. The type of the worker can be overridden in a derived
261 // class with the appropriate implementation of allocate_worker().
262 bool initialize_workers();
263 };
264
265 // Class GangWorker:
266 // Several instances of this class run in parallel as workers for a gang.
267 class GangWorker: public WorkerThread {
268 public:
269 // Constructors and destructor.
270 GangWorker(AbstractWorkGang* gang, uint id);
271
272 // The only real method: run a task for the gang.
273 virtual void run();
274 // Predicate for Thread
275 virtual bool is_GC_task_thread() const;
276 virtual bool is_ConcurrentGC_thread() const;
277 // Printing
278 void print_on(outputStream* st) const;
279 virtual void print() const { print_on(tty); }
280 protected:
281 AbstractWorkGang* _gang;
282
283 virtual void initialize();
284 virtual void loop();
285
286 public:
287 AbstractWorkGang* gang() const { return _gang; }
288 };
289
290 class FlexibleWorkGang: public WorkGang {
291 protected:
292 int _active_workers;
293 public:
294 // Constructor and destructor.
295 FlexibleWorkGang(const char* name, int workers,
296 bool are_GC_task_threads,
297 bool are_ConcurrentGC_threads) :
298 WorkGang(name, workers, are_GC_task_threads, are_ConcurrentGC_threads) {
299 _active_workers = ParallelGCThreads;
300 };
301 // Accessors for fields
302 virtual int active_workers() const { return _active_workers; }
303 void set_active_workers(int v) { _active_workers = v; }
304 };
305
306 // Work gangs in garbage collectors: 2009-06-10
307 //
308 // SharedHeap - work gang for stop-the-world parallel collection.
309 // Used by
310 // ParNewGeneration
311 // CMSParRemarkTask
312 // CMSRefProcTaskExecutor
313 // G1CollectedHeap
314 // G1ParFinalCountTask
315 // ConcurrentMark
316 // CMSCollector
317
318 // A class that acts as a synchronisation barrier. Workers enter
319 // the barrier and must wait until all other workers have entered
320 // before any of them may leave.
321
322 class WorkGangBarrierSync : public StackObj {
323 protected:
324 Monitor _monitor;
325 int _n_workers;
326 int _n_completed;
327 bool _should_reset;
328
329 Monitor* monitor() { return &_monitor; }
330 int n_workers() { return _n_workers; }
331 int n_completed() { return _n_completed; }
332 bool should_reset() { return _should_reset; }
333
334 void zero_completed() { _n_completed = 0; }
335 void inc_completed() { _n_completed++; }
336
337 void set_should_reset(bool v) { _should_reset = v; }
338
339 public:
340 WorkGangBarrierSync();
341 WorkGangBarrierSync(int n_workers, const char* name);
342
343 // Set the number of workers that will use the barrier.
344 // Must be called before any of the workers start running.
345 void set_n_workers(int n_workers);
346
347 // Enter the barrier. A worker that enters the barrier will
348 // not be allowed to leave until all other threads have
349 // also entered the barrier.
350 void enter();
351 };
352
353 // A class to manage claiming of subtasks within a group of tasks. The
354 // subtasks will be identified by integer indices, usually elements of an
355 // enumeration type.
356
357 class SubTasksDone: public CHeapObj {
358 jint* _tasks;
359 int _n_tasks;
360 int _n_threads;
361 jint _threads_completed;
362 #ifdef ASSERT
363 volatile jint _claimed;
364 #endif
365
366 // Set all tasks to unclaimed.
367 void clear();
368
369 public:
370 // Initializes "this" to a state in which there are "n" tasks to be
371 // processed, none of the which are originally claimed. The number of
372 // threads doing the tasks is initialized 1.
373 SubTasksDone(int n);
374
375 // True iff the object is in a valid state.
376 bool valid();
377
378 // Get/set the number of parallel threads doing the tasks to "t". Can only
379 // be called before tasks start or after they are complete.
380 int n_threads() { return _n_threads; }
381 void set_n_threads(int t);
382
383 // Returns "false" if the task "t" is unclaimed, and ensures that task is
384 // claimed. The task "t" is required to be within the range of "this".
385 bool is_task_claimed(int t);
386
387 // The calling thread asserts that it has attempted to claim all the
388 // tasks that it will try to claim. Every thread in the parallel task
389 // must execute this. (When the last thread does so, the task array is
390 // cleared.)
391 void all_tasks_completed();
392
393 // Destructor.
394 ~SubTasksDone();
395 };
396
397 // As above, but for sequential tasks, i.e. instead of claiming
398 // sub-tasks from a set (possibly an enumeration), claim sub-tasks
399 // in sequential order. This is ideal for claiming dynamically
400 // partitioned tasks (like striding in the parallel remembered
401 // set scanning). Note that unlike the above class this is
402 // a stack object - is there any reason for it not to be?
403
404 class SequentialSubTasksDone : public StackObj {
405 protected:
406 jint _n_tasks; // Total number of tasks available.
407 jint _n_claimed; // Number of tasks claimed.
408 // _n_threads is used to determine when a sub task is done.
409 // See comments on SubTasksDone::_n_threads
410 jint _n_threads; // Total number of parallel threads.
411 jint _n_completed; // Number of completed threads.
412
413 void clear();
414
415 public:
416 SequentialSubTasksDone() {
417 clear();
418 }
419 ~SequentialSubTasksDone() {}
420
421 // True iff the object is in a valid state.
422 bool valid();
423
424 // number of tasks
425 jint n_tasks() const { return _n_tasks; }
426
427 // Get/set the number of parallel threads doing the tasks to t.
428 // Should be called before the task starts but it is safe
429 // to call this once a task is running provided that all
430 // threads agree on the number of threads.
431 int n_threads() { return _n_threads; }
432 void set_n_threads(int t) { _n_threads = t; }
433
434 // Set the number of tasks to be claimed to t. As above,
435 // should be called before the tasks start but it is safe
436 // to call this once a task is running provided all threads
437 // agree on the number of tasks.
438 void set_n_tasks(int t) { _n_tasks = t; }
439
440 // Returns false if the next task in the sequence is unclaimed,
441 // and ensures that it is claimed. Will set t to be the index
442 // of the claimed task in the sequence. Will return true if
443 // the task cannot be claimed and there are none left to claim.
444 bool is_task_claimed(int& t);
445
446 // The calling thread asserts that it has attempted to claim
447 // all the tasks it possibly can in the sequence. Every thread
448 // claiming tasks must promise call this. Returns true if this
449 // is the last thread to complete so that the thread can perform
450 // cleanup if necessary.
451 bool all_tasks_completed();
452 };
453
454 // Represents a set of free small integer ids.
455 class FreeIdSet {
456 enum {
457 end_of_list = -1,
458 claimed = -2
459 };
460
461 int _sz;
462 Monitor* _mon;
463
464 int* _ids;
465 int _hd;
466 int _waiters;
467 int _claimed;
468
469 static bool _safepoint;
470 typedef FreeIdSet* FreeIdSetPtr;
471 static const int NSets = 10;
472 static FreeIdSetPtr _sets[NSets];
473 static bool _stat_init;
474 int _index;
475
476 public:
477 FreeIdSet(int sz, Monitor* mon);
478 ~FreeIdSet();
479
480 static void set_safepoint(bool b);
481
482 // Attempt to claim the given id permanently. Returns "true" iff
483 // successful.
484 bool claim_perm_id(int i);
485
486 // Returns an unclaimed parallel id (waiting for one to be released if
487 // necessary). Returns "-1" if a GC wakes up a wait for an id.
488 int claim_par_id();
489
490 void release_par_id(int id);
491 };
492
493 #endif // SHARE_VM_UTILITIES_WORKGROUP_HPP