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6593758: RFE: Enhance GC ergonomics to dynamically choose ParallelGCThreads

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Select number of GC threads dynamically based on heap usage and number of Java threads

Reviewed-by: johnc, ysr, jcoomes
This commit is contained in:
Jon Masamitsu 2011-08-09 10:16:01 -07:00
parent 098ed89645
commit 15070123fa
39 changed files with 1523 additions and 231 deletions
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16
hotspot/src/share/vm/runtime/thread.cpp
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@ -778,12 +778,12 @@ bool Thread::claim_oops_do_par_case(int strong_roots_parity) {
return true;
} else {
guarantee(res == strong_roots_parity, "Or else what?");
assert(SharedHeap::heap()->n_par_threads() > 0,
"Should only fail when parallel.");
assert(SharedHeap::heap()->workers()->active_workers() > 0,
"Should only fail when parallel.");
return false;
}
}
assert(SharedHeap::heap()->n_par_threads() > 0,
assert(SharedHeap::heap()->workers()->active_workers() > 0,
"Should only fail when parallel.");
return false;
}
@ -3939,7 +3939,15 @@ void Threads::possibly_parallel_oops_do(OopClosure* f, CodeBlobClosure* cf) {
// root groups. Overhead should be small enough to use all the time,
// even in sequential code.
SharedHeap* sh = SharedHeap::heap();
bool is_par = (sh->n_par_threads() > 0);
// Cannot yet substitute active_workers for n_par_threads
// because of G1CollectedHeap::verify() use of
// SharedHeap::process_strong_roots(). n_par_threads == 0 will
// turn off parallelism in process_strong_roots while active_workers
// is being used for parallelism elsewhere.
bool is_par = sh->n_par_threads() > 0;
assert(!is_par ||
(SharedHeap::heap()->n_par_threads() ==
SharedHeap::heap()->workers()->active_workers()), "Mismatch");
int cp = SharedHeap::heap()->strong_roots_parity();
ALL_JAVA_THREADS(p) {
if (p->claim_oops_do(is_par, cp)) {