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8005032: G1: Cleanup serial reference processing closures in concurrent marking

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Reuse the parallel reference processing oop closures during serial reference processing.

Reviewed-by: brutisso
This commit is contained in:
John Cuthbertson 2013-02-05 09:13:05 -08:00
parent ea33ae6c4d
commit c2bb152e6c
2 changed files with 117 additions and 131 deletions
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244
hotspot/src/share/vm/gc_implementation/g1/concurrentMark.cpp
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@ -2167,7 +2167,8 @@ void ConcurrentMark::completeCleanup() {
assert(tmp_free_list.is_empty(), "post-condition");
}
// Support closures for reference procssing in G1
// Supporting Object and Oop closures for reference discovery
// and processing in during marking
bool G1CMIsAliveClosure::do_object_b(oop obj) {
HeapWord* addr = (HeapWord*)obj;
@ -2175,73 +2176,26 @@ bool G1CMIsAliveClosure::do_object_b(oop obj) {
(!_g1->is_in_g1_reserved(addr) || !_g1->is_obj_ill(obj));
}
class G1CMKeepAliveClosure: public ExtendedOopClosure {
G1CollectedHeap* _g1;
ConcurrentMark* _cm;
public:
G1CMKeepAliveClosure(G1CollectedHeap* g1, ConcurrentMark* cm) :
_g1(g1), _cm(cm) {
assert(Thread::current()->is_VM_thread(), "otherwise fix worker id");
}
// 'Keep Alive' oop closure used by both serial parallel reference processing.
// Uses the CMTask associated with a worker thread (for serial reference
// processing the CMTask for worker 0 is used) to preserve (mark) and
// trace referent objects.
//
// Using the CMTask and embedded local queues avoids having the worker
// threads operating on the global mark stack. This reduces the risk
// of overflowing the stack - which we would rather avoid at this late
// state. Also using the tasks' local queues removes the potential
// of the workers interfering with each other that could occur if
// operating on the global stack.
virtual void do_oop(narrowOop* p) { do_oop_work(p); }
virtual void do_oop( oop* p) { do_oop_work(p); }
template <class T> void do_oop_work(T* p) {
oop obj = oopDesc::load_decode_heap_oop(p);
HeapWord* addr = (HeapWord*)obj;
if (_cm->verbose_high()) {
gclog_or_tty->print_cr("\t[0] we're looking at location "
"*"PTR_FORMAT" = "PTR_FORMAT,
p, (void*) obj);
}
if (_g1->is_in_g1_reserved(addr) && _g1->is_obj_ill(obj)) {
_cm->mark_and_count(obj);
_cm->mark_stack_push(obj);
}
}
};
class G1CMDrainMarkingStackClosure: public VoidClosure {
ConcurrentMark* _cm;
CMMarkStack* _markStack;
G1CMKeepAliveClosure* _oopClosure;
public:
G1CMDrainMarkingStackClosure(ConcurrentMark* cm, CMMarkStack* markStack,
G1CMKeepAliveClosure* oopClosure) :
_cm(cm),
_markStack(markStack),
_oopClosure(oopClosure) { }
void do_void() {
_markStack->drain(_oopClosure, _cm->nextMarkBitMap(), false);
}
};
// 'Keep Alive' closure used by parallel reference processing.
// An instance of this closure is used in the parallel reference processing
// code rather than an instance of G1CMKeepAliveClosure. We could have used
// the G1CMKeepAliveClosure as it is MT-safe. Also reference objects are
// placed on to discovered ref lists once so we can mark and push with no
// need to check whether the object has already been marked. Using the
// G1CMKeepAliveClosure would mean, however, having all the worker threads
// operating on the global mark stack. This means that an individual
// worker would be doing lock-free pushes while it processes its own
// discovered ref list followed by drain call. If the discovered ref lists
// are unbalanced then this could cause interference with the other
// workers. Using a CMTask (and its embedded local data structures)
// avoids that potential interference.
class G1CMParKeepAliveAndDrainClosure: public OopClosure {
class G1CMKeepAliveAndDrainClosure: public OopClosure {
ConcurrentMark* _cm;
CMTask* _task;
int _ref_counter_limit;
int _ref_counter;
public:
G1CMParKeepAliveAndDrainClosure(ConcurrentMark* cm, CMTask* task) :
_cm(cm), _task(task),
_ref_counter_limit(G1RefProcDrainInterval) {
G1CMKeepAliveAndDrainClosure(ConcurrentMark* cm, CMTask* task) :
_cm(cm), _task(task), _ref_counter_limit(G1RefProcDrainInterval) {
assert(_ref_counter_limit > 0, "sanity");
_ref_counter = _ref_counter_limit;
}
@ -2262,18 +2216,22 @@ class G1CMParKeepAliveAndDrainClosure: public OopClosure {
_ref_counter--;
if (_ref_counter == 0) {
// We have dealt with _ref_counter_limit references, pushing them and objects
// reachable from them on to the local stack (and possibly the global stack).
// Call do_marking_step() to process these entries. We call the routine in a
// loop, which we'll exit if there's nothing more to do (i.e. we're done
// with the entries that we've pushed as a result of the deal_with_reference
// calls above) or we overflow.
// Note: CMTask::do_marking_step() can set the CMTask::has_aborted() flag
// while there may still be some work to do. (See the comment at the
// beginning of CMTask::do_marking_step() for those conditions - one of which
// is reaching the specified time target.) It is only when
// CMTask::do_marking_step() returns without setting the has_aborted() flag
// that the marking has completed.
// We have dealt with _ref_counter_limit references, pushing them
// and objects reachable from them on to the local stack (and
// possibly the global stack). Call CMTask::do_marking_step() to
// process these entries.
//
// We call CMTask::do_marking_step() in a loop, which we'll exit if
// there's nothing more to do (i.e. we're done with the entries that
// were pushed as a result of the CMTask::deal_with_reference() calls
// above) or we overflow.
//
// Note: CMTask::do_marking_step() can set the CMTask::has_aborted()
// flag while there may still be some work to do. (See the comment at
// the beginning of CMTask::do_marking_step() for those conditions -
// one of which is reaching the specified time target.) It is only
// when CMTask::do_marking_step() returns without setting the
// has_aborted() flag that the marking step has completed.
do {
double mark_step_duration_ms = G1ConcMarkStepDurationMillis;
_task->do_marking_step(mark_step_duration_ms,
@ -2290,36 +2248,59 @@ class G1CMParKeepAliveAndDrainClosure: public OopClosure {
}
};
class G1CMParDrainMarkingStackClosure: public VoidClosure {
// 'Drain' oop closure used by both serial and parallel reference processing.
// Uses the CMTask associated with a given worker thread (for serial
// reference processing the CMtask for worker 0 is used). Calls the
// do_marking_step routine, with an unbelievably large timeout value,
// to drain the marking data structures of the remaining entries
// added by the 'keep alive' oop closure above.
class G1CMDrainMarkingStackClosure: public VoidClosure {
ConcurrentMark* _cm;
CMTask* _task;
CMTask* _task;
bool _do_stealing;
bool _do_termination;
public:
G1CMParDrainMarkingStackClosure(ConcurrentMark* cm, CMTask* task) :
_cm(cm), _task(task) { }
G1CMDrainMarkingStackClosure(ConcurrentMark* cm, CMTask* task, bool is_par) :
_cm(cm), _task(task) {
assert(is_par || _task->worker_id() == 0,
"Only task for worker 0 should be used if ref processing is single threaded");
// We only allow stealing and only enter the termination protocol
// in CMTask::do_marking_step() if this closure is being instantiated
// for parallel reference processing.
_do_stealing = _do_termination = is_par;
}
void do_void() {
do {
if (_cm->verbose_high()) {
gclog_or_tty->print_cr("\t[%u] Drain: Calling do marking_step",
_task->worker_id());
gclog_or_tty->print_cr("\t[%u] Drain: Calling do_marking_step - "
"stealing: %s, termination: %s",
_task->worker_id(),
BOOL_TO_STR(_do_stealing),
BOOL_TO_STR(_do_termination));
}
// We call CMTask::do_marking_step() to completely drain the local and
// global marking stacks. The routine is called in a loop, which we'll
// exit if there's nothing more to do (i.e. we'completely drained the
// entries that were pushed as a result of applying the
// G1CMParKeepAliveAndDrainClosure to the entries on the discovered ref
// lists above) or we overflow the global marking stack.
// Note: CMTask::do_marking_step() can set the CMTask::has_aborted() flag
// while there may still be some work to do. (See the comment at the
// beginning of CMTask::do_marking_step() for those conditions - one of which
// is reaching the specified time target.) It is only when
// CMTask::do_marking_step() returns without setting the has_aborted() flag
// that the marking has completed.
// We call CMTask::do_marking_step() to completely drain the local
// and global marking stacks of entries pushed by the 'keep alive'
// oop closure (an instance of G1CMKeepAliveAndDrainClosure above).
//
// CMTask::do_marking_step() is called in a loop, which we'll exit
// if there's nothing more to do (i.e. we'completely drained the
// entries that were pushed as a a result of applying the 'keep alive'
// closure to the entries on the discovered ref lists) or we overflow
// the global marking stack.
//
// Note: CMTask::do_marking_step() can set the CMTask::has_aborted()
// flag while there may still be some work to do. (See the comment at
// the beginning of CMTask::do_marking_step() for those conditions -
// one of which is reaching the specified time target.) It is only
// when CMTask::do_marking_step() returns without setting the
// has_aborted() flag that the marking step has completed.
_task->do_marking_step(1000000000.0 /* something very large */,
true /* do_stealing */,
true /* do_termination */);
_do_stealing,
_do_termination);
} while (_task->has_aborted() && !_cm->has_overflown());
}
};
@ -2352,19 +2333,23 @@ class G1CMRefProcTaskProxy: public AbstractGangTask {
ProcessTask& _proc_task;
G1CollectedHeap* _g1h;
ConcurrentMark* _cm;
bool _processing_is_mt;
public:
G1CMRefProcTaskProxy(ProcessTask& proc_task,
G1CollectedHeap* g1h,
ConcurrentMark* cm) :
AbstractGangTask("Process reference objects in parallel"),
_proc_task(proc_task), _g1h(g1h), _cm(cm) { }
_proc_task(proc_task), _g1h(g1h), _cm(cm) {
ReferenceProcessor* rp = _g1h->ref_processor_cm();
_processing_is_mt = rp->processing_is_mt();
}
virtual void work(uint worker_id) {
CMTask* marking_task = _cm->task(worker_id);
G1CMIsAliveClosure g1_is_alive(_g1h);
G1CMParKeepAliveAndDrainClosure g1_par_keep_alive(_cm, marking_task);
G1CMParDrainMarkingStackClosure g1_par_drain(_cm, marking_task);
G1CMKeepAliveAndDrainClosure g1_par_keep_alive(_cm, marking_task);
G1CMDrainMarkingStackClosure g1_par_drain(_cm, marking_task, _processing_is_mt);
_proc_task.work(worker_id, g1_is_alive, g1_par_keep_alive, g1_par_drain);
}
@ -2372,6 +2357,7 @@ public:
void G1CMRefProcTaskExecutor::execute(ProcessTask& proc_task) {
assert(_workers != NULL, "Need parallel worker threads.");
assert(_g1h->ref_processor_cm()->processing_is_mt(), "processing is not MT");
G1CMRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _cm);
@ -2399,6 +2385,7 @@ public:
void G1CMRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
assert(_workers != NULL, "Need parallel worker threads.");
assert(_g1h->ref_processor_cm()->processing_is_mt(), "processing is not MT");
G1CMRefEnqueueTaskProxy enq_task_proxy(enq_task);
@ -2429,59 +2416,58 @@ void ConcurrentMark::weakRefsWork(bool clear_all_soft_refs) {
// See the comment in G1CollectedHeap::ref_processing_init()
// about how reference processing currently works in G1.
// Process weak references.
// Set the soft reference policy
rp->setup_policy(clear_all_soft_refs);
assert(_markStack.isEmpty(), "mark stack should be empty");
G1CMKeepAliveClosure g1_keep_alive(g1h, this);
G1CMDrainMarkingStackClosure
g1_drain_mark_stack(this, &_markStack, &g1_keep_alive);
// Non-MT instances 'Keep Alive' and 'Complete GC' oop closures.
G1CMKeepAliveAndDrainClosure g1_keep_alive(this, task(0));
G1CMDrainMarkingStackClosure g1_drain_mark_stack(this, task(0), false);
// We need at least one active thread. If reference processing is
// not multi-threaded we use the current (ConcurrentMarkThread) thread,
// otherwise we use the work gang from the G1CollectedHeap and we
// utilize all the worker threads we can.
uint active_workers = (rp->processing_is_mt() && g1h->workers() != NULL
? g1h->workers()->active_workers()
: 1U);
// We use the work gang from the G1CollectedHeap and we utilize all
// the worker threads.
uint active_workers = g1h->workers() ? g1h->workers()->active_workers() : 1U;
active_workers = MAX2(MIN2(active_workers, _max_worker_id), 1U);
G1CMRefProcTaskExecutor par_task_executor(g1h, this,
g1h->workers(), active_workers);
if (rp->processing_is_mt()) {
// Set the degree of MT here. If the discovery is done MT, there
// may have been a different number of threads doing the discovery
// and a different number of discovered lists may have Ref objects.
// That is OK as long as the Reference lists are balanced (see
// balance_all_queues() and balance_queues()).
rp->set_active_mt_degree(active_workers);
AbstractRefProcTaskExecutor* executor = (rp->processing_is_mt()
? &par_task_executor
: NULL);
rp->process_discovered_references(&g1_is_alive,
// Set the degree of MT processing here. If the discovery was done MT,
// the number of threads involved during discovery could differ from
// the number of active workers. This is OK as long as the discovered
// Reference lists are balanced (see balance_all_queues() and balance_queues()).
rp->set_active_mt_degree(active_workers);
// Process the weak references.
rp->process_discovered_references(&g1_is_alive,
&g1_keep_alive,
&g1_drain_mark_stack,
&par_task_executor);
executor);
// The work routines of the parallel keep_alive and drain_marking_stack
// will set the has_overflown flag if we overflow the global marking
// stack.
} else {
rp->process_discovered_references(&g1_is_alive,
&g1_keep_alive,
&g1_drain_mark_stack,
NULL);
}
// The do_oop work routines of the keep_alive and drain_marking_stack
// oop closures will set the has_overflown flag if we overflow the
// global marking stack.
assert(_markStack.overflow() || _markStack.isEmpty(),
"mark stack should be empty (unless it overflowed)");
if (_markStack.overflow()) {
// Should have been done already when we tried to push an
// This should have been done already when we tried to push an
// entry on to the global mark stack. But let's do it again.
set_has_overflown();
}
if (rp->processing_is_mt()) {
assert(rp->num_q() == active_workers, "why not");
rp->enqueue_discovered_references(&par_task_executor);
} else {
rp->enqueue_discovered_references();
}
assert(rp->num_q() == active_workers, "why not");
rp->enqueue_discovered_references(executor);
rp->verify_no_references_recorded();
assert(!rp->discovery_enabled(), "Post condition");