1.1 --- a/src/share/vm/gc_implementation/parallelScavenge/gcTaskManager.hpp Tue Nov 22 04:47:10 2011 -0500
1.2 +++ b/src/share/vm/gc_implementation/parallelScavenge/gcTaskManager.hpp Tue Aug 09 10:16:01 2011 -0700
1.3 @@ -45,6 +45,7 @@
1.4 class ReleasingBarrierGCTask;
1.5 class NotifyingBarrierGCTask;
1.6 class WaitForBarrierGCTask;
1.7 +class IdleGCTask;
1.8 // A free list of Monitor*'s.
1.9 class MonitorSupply;
1.10
1.11 @@ -64,7 +65,8 @@
1.12 unknown_task,
1.13 ordinary_task,
1.14 barrier_task,
1.15 - noop_task
1.16 + noop_task,
1.17 + idle_task
1.18 };
1.19 static const char* to_string(kind value);
1.20 };
1.21 @@ -108,6 +110,9 @@
1.22 bool is_noop_task() const {
1.23 return kind()==Kind::noop_task;
1.24 }
1.25 + bool is_idle_task() const {
1.26 + return kind()==Kind::idle_task;
1.27 + }
1.28 void print(const char* message) const PRODUCT_RETURN;
1.29 protected:
1.30 // Constructors: Only create subclasses.
1.31 @@ -153,6 +158,7 @@
1.32 assert(((insert_end() == NULL && remove_end() == NULL) ||
1.33 (insert_end() != NULL && remove_end() != NULL)),
1.34 "insert_end and remove_end don't match");
1.35 + assert((insert_end() != NULL) || (_length == 0), "Not empty");
1.36 return insert_end() == NULL;
1.37 }
1.38 uint length() const {
1.39 @@ -204,6 +210,8 @@
1.40 GCTask* remove(); // Remove from remove end.
1.41 GCTask* remove(GCTask* task); // Remove from the middle.
1.42 void print(const char* message) const PRODUCT_RETURN;
1.43 + // Debug support
1.44 + void verify_length() const PRODUCT_RETURN;
1.45 };
1.46
1.47 // A GCTaskQueue that can be synchronized.
1.48 @@ -285,12 +293,76 @@
1.49 }
1.50 };
1.51
1.52 +// Dynamic number of GC threads
1.53 +//
1.54 +// GC threads wait in get_task() for work (i.e., a task) to perform.
1.55 +// When the number of GC threads was static, the number of tasks
1.56 +// created to do a job was equal to or greater than the maximum
1.57 +// number of GC threads (ParallelGCThreads). The job might be divided
1.58 +// into a number of tasks greater than the number of GC threads for
1.59 +// load balancing (i.e., over partitioning). The last task to be
1.60 +// executed by a GC thread in a job is a work stealing task. A
1.61 +// GC thread that gets a work stealing task continues to execute
1.62 +// that task until the job is done. In the static number of GC theads
1.63 +// case, tasks are added to a queue (FIFO). The work stealing tasks are
1.64 +// the last to be added. Once the tasks are added, the GC threads grab
1.65 +// a task and go. A single thread can do all the non-work stealing tasks
1.66 +// and then execute a work stealing and wait for all the other GC threads
1.67 +// to execute their work stealing task.
1.68 +// In the dynamic number of GC threads implementation, idle-tasks are
1.69 +// created to occupy the non-participating or "inactive" threads. An
1.70 +// idle-task makes the GC thread wait on a barrier that is part of the
1.71 +// GCTaskManager. The GC threads that have been "idled" in a IdleGCTask
1.72 +// are released once all the active GC threads have finished their work
1.73 +// stealing tasks. The GCTaskManager does not wait for all the "idled"
1.74 +// GC threads to resume execution. When those GC threads do resume
1.75 +// execution in the course of the thread scheduling, they call get_tasks()
1.76 +// as all the other GC threads do. Because all the "idled" threads are
1.77 +// not required to execute in order to finish a job, it is possible for
1.78 +// a GC thread to still be "idled" when the next job is started. Such
1.79 +// a thread stays "idled" for the next job. This can result in a new
1.80 +// job not having all the expected active workers. For example if on
1.81 +// job requests 4 active workers out of a total of 10 workers so the
1.82 +// remaining 6 are "idled", if the next job requests 6 active workers
1.83 +// but all 6 of the "idled" workers are still idle, then the next job
1.84 +// will only get 4 active workers.
1.85 +// The implementation for the parallel old compaction phase has an
1.86 +// added complication. In the static case parold partitions the chunks
1.87 +// ready to be filled into stacks, one for each GC thread. A GC thread
1.88 +// executing a draining task (drains the stack of ready chunks)
1.89 +// claims a stack according to it's id (the unique ordinal value assigned
1.90 +// to each GC thread). In the dynamic case not all GC threads will
1.91 +// actively participate so stacks with ready to fill chunks can only be
1.92 +// given to the active threads. An initial implementation chose stacks
1.93 +// number 1-n to get the ready chunks and required that GC threads
1.94 +// 1-n be the active workers. This was undesirable because it required
1.95 +// certain threads to participate. In the final implementation a
1.96 +// list of stacks equal in number to the active workers are filled
1.97 +// with ready chunks. GC threads that participate get a stack from
1.98 +// the task (DrainStacksCompactionTask), empty the stack, and then add it to a
1.99 +// recycling list at the end of the task. If the same GC thread gets
1.100 +// a second task, it gets a second stack to drain and returns it. The
1.101 +// stacks are added to a recycling list so that later stealing tasks
1.102 +// for this tasks can get a stack from the recycling list. Stealing tasks
1.103 +// use the stacks in its work in a way similar to the draining tasks.
1.104 +// A thread is not guaranteed to get anything but a stealing task and
1.105 +// a thread that only gets a stealing task has to get a stack. A failed
1.106 +// implementation tried to have the GC threads keep the stack they used
1.107 +// during a draining task for later use in the stealing task but that didn't
1.108 +// work because as noted a thread is not guaranteed to get a draining task.
1.109 +//
1.110 +// For PSScavenge and ParCompactionManager the GC threads are
1.111 +// held in the GCTaskThread** _thread array in GCTaskManager.
1.112 +
1.113 +
1.114 class GCTaskManager : public CHeapObj {
1.115 friend class ParCompactionManager;
1.116 friend class PSParallelCompact;
1.117 friend class PSScavenge;
1.118 friend class PSRefProcTaskExecutor;
1.119 friend class RefProcTaskExecutor;
1.120 + friend class GCTaskThread;
1.121 + friend class IdleGCTask;
1.122 private:
1.123 // Instance state.
1.124 NotifyDoneClosure* _ndc; // Notify on completion.
1.125 @@ -298,6 +370,7 @@
1.126 Monitor* _monitor; // Notification of changes.
1.127 SynchronizedGCTaskQueue* _queue; // Queue of tasks.
1.128 GCTaskThread** _thread; // Array of worker threads.
1.129 + uint _active_workers; // Number of active workers.
1.130 uint _busy_workers; // Number of busy workers.
1.131 uint _blocking_worker; // The worker that's blocking.
1.132 bool* _resource_flag; // Array of flag per threads.
1.133 @@ -307,6 +380,8 @@
1.134 uint _emptied_queue; // Times we emptied the queue.
1.135 NoopGCTask* _noop_task; // The NoopGCTask instance.
1.136 uint _noop_tasks; // Count of noop tasks.
1.137 + WaitForBarrierGCTask* _idle_inactive_task;// Task for inactive workers
1.138 + volatile uint _idle_workers; // Number of idled workers
1.139 public:
1.140 // Factory create and destroy methods.
1.141 static GCTaskManager* create(uint workers) {
1.142 @@ -324,6 +399,9 @@
1.143 uint busy_workers() const {
1.144 return _busy_workers;
1.145 }
1.146 + volatile uint idle_workers() const {
1.147 + return _idle_workers;
1.148 + }
1.149 // Pun between Monitor* and Mutex*
1.150 Monitor* monitor() const {
1.151 return _monitor;
1.152 @@ -331,6 +409,9 @@
1.153 Monitor * lock() const {
1.154 return _monitor;
1.155 }
1.156 + WaitForBarrierGCTask* idle_inactive_task() {
1.157 + return _idle_inactive_task;
1.158 + }
1.159 // Methods.
1.160 // Add the argument task to be run.
1.161 void add_task(GCTask* task);
1.162 @@ -350,6 +431,10 @@
1.163 bool should_release_resources(uint which); // Predicate.
1.164 // Note the release of resources by the argument worker.
1.165 void note_release(uint which);
1.166 + // Create IdleGCTasks for inactive workers and start workers
1.167 + void task_idle_workers();
1.168 + // Release the workers in IdleGCTasks
1.169 + void release_idle_workers();
1.170 // Constants.
1.171 // A sentinel worker identifier.
1.172 static uint sentinel_worker() {
1.173 @@ -375,6 +460,15 @@
1.174 uint workers() const {
1.175 return _workers;
1.176 }
1.177 + void set_active_workers(uint v) {
1.178 + assert(v <= _workers, "Trying to set more workers active than there are");
1.179 + _active_workers = MIN2(v, _workers);
1.180 + assert(v != 0, "Trying to set active workers to 0");
1.181 + _active_workers = MAX2(1U, _active_workers);
1.182 + }
1.183 + // Sets the number of threads that will be used in a collection
1.184 + void set_active_gang();
1.185 +
1.186 NotifyDoneClosure* notify_done_closure() const {
1.187 return _ndc;
1.188 }
1.189 @@ -457,8 +551,21 @@
1.190 void reset_noop_tasks() {
1.191 _noop_tasks = 0;
1.192 }
1.193 + void increment_idle_workers() {
1.194 + _idle_workers++;
1.195 + }
1.196 + void decrement_idle_workers() {
1.197 + _idle_workers--;
1.198 + }
1.199 // Other methods.
1.200 void initialize();
1.201 +
1.202 + public:
1.203 + // Return true if all workers are currently active.
1.204 + bool all_workers_active() { return workers() == active_workers(); }
1.205 + uint active_workers() const {
1.206 + return _active_workers;
1.207 + }
1.208 };
1.209
1.210 //
1.211 @@ -475,6 +582,8 @@
1.212 static NoopGCTask* create();
1.213 static NoopGCTask* create_on_c_heap();
1.214 static void destroy(NoopGCTask* that);
1.215 +
1.216 + virtual char* name() { return (char *)"noop task"; }
1.217 // Methods from GCTask.
1.218 void do_it(GCTaskManager* manager, uint which) {
1.219 // Nothing to do.
1.220 @@ -518,6 +627,8 @@
1.221 }
1.222 // Destructor-like method.
1.223 void destruct();
1.224 +
1.225 + virtual char* name() { return (char *)"barrier task"; }
1.226 // Methods.
1.227 // Wait for this to be the only task running.
1.228 void do_it_internal(GCTaskManager* manager, uint which);
1.229 @@ -586,11 +697,13 @@
1.230 // the BarrierGCTask is done.
1.231 // This may cover many of the uses of NotifyingBarrierGCTasks.
1.232 class WaitForBarrierGCTask : public BarrierGCTask {
1.233 + friend class GCTaskManager;
1.234 + friend class IdleGCTask;
1.235 private:
1.236 // Instance state.
1.237 - Monitor* _monitor; // Guard and notify changes.
1.238 - bool _should_wait; // true=>wait, false=>proceed.
1.239 - const bool _is_c_heap_obj; // Was allocated on the heap.
1.240 + Monitor* _monitor; // Guard and notify changes.
1.241 + volatile bool _should_wait; // true=>wait, false=>proceed.
1.242 + const bool _is_c_heap_obj; // Was allocated on the heap.
1.243 public:
1.244 virtual char* name() { return (char *) "waitfor-barrier-task"; }
1.245
1.246 @@ -600,7 +713,10 @@
1.247 static void destroy(WaitForBarrierGCTask* that);
1.248 // Methods.
1.249 void do_it(GCTaskManager* manager, uint which);
1.250 - void wait_for();
1.251 + void wait_for(bool reset);
1.252 + void set_should_wait(bool value) {
1.253 + _should_wait = value;
1.254 + }
1.255 protected:
1.256 // Constructor. Clients use factory, but there might be subclasses.
1.257 WaitForBarrierGCTask(bool on_c_heap);
1.258 @@ -613,14 +729,38 @@
1.259 bool should_wait() const {
1.260 return _should_wait;
1.261 }
1.262 - void set_should_wait(bool value) {
1.263 - _should_wait = value;
1.264 - }
1.265 bool is_c_heap_obj() {
1.266 return _is_c_heap_obj;
1.267 }
1.268 };
1.269
1.270 +// Task that is used to idle a GC task when fewer than
1.271 +// the maximum workers are wanted.
1.272 +class IdleGCTask : public GCTask {
1.273 + const bool _is_c_heap_obj; // Was allocated on the heap.
1.274 + public:
1.275 + bool is_c_heap_obj() {
1.276 + return _is_c_heap_obj;
1.277 + }
1.278 + // Factory create and destroy methods.
1.279 + static IdleGCTask* create();
1.280 + static IdleGCTask* create_on_c_heap();
1.281 + static void destroy(IdleGCTask* that);
1.282 +
1.283 + virtual char* name() { return (char *)"idle task"; }
1.284 + // Methods from GCTask.
1.285 + virtual void do_it(GCTaskManager* manager, uint which);
1.286 +protected:
1.287 + // Constructor.
1.288 + IdleGCTask(bool on_c_heap) :
1.289 + GCTask(GCTask::Kind::idle_task),
1.290 + _is_c_heap_obj(on_c_heap) {
1.291 + // Nothing to do.
1.292 + }
1.293 + // Destructor-like method.
1.294 + void destruct();
1.295 +};
1.296 +
1.297 class MonitorSupply : public AllStatic {
1.298 private:
1.299 // State.
