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8196071: Change G1 Full GC heap and thread sizing ergonomics

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Reviewed-by: tschatzl, sangheki
This commit is contained in:
Stefan Johansson 2018-04-19 09:15:17 +02:00
parent edbbeae978
commit ffd8b1f9bd
3 changed files with 37 additions and 3 deletions
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35
src/hotspot/share/gc/g1/g1FullCollector.cpp
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@ -1,5 +1,5 @@
/*
* Copyright (c) 2017, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 2017, 2018, 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
@ -37,6 +37,7 @@
#include "gc/g1/g1OopClosures.hpp"
#include "gc/g1/g1Policy.hpp"
#include "gc/g1/g1StringDedup.hpp"
#include "gc/shared/adaptiveSizePolicy.hpp"
#include "gc/shared/gcTraceTime.inline.hpp"
#include "gc/shared/preservedMarks.hpp"
#include "gc/shared/referenceProcessor.hpp"
@ -72,10 +73,40 @@ ReferenceProcessor* G1FullCollector::reference_processor() {
return _heap->ref_processor_stw();
}
uint G1FullCollector::calc_active_workers() {
G1CollectedHeap* heap = G1CollectedHeap::heap();
uint max_worker_count = heap->workers()->total_workers();
// Only calculate number of workers if UseDynamicNumberOfGCThreads
// is enabled, otherwise use max.
if (!UseDynamicNumberOfGCThreads) {
return max_worker_count;
}
// Consider G1HeapWastePercent to decide max number of workers. Each worker
// will in average cause half a region waste.
uint max_wasted_regions_allowed = ((heap->num_regions() * G1HeapWastePercent) / 100);
uint waste_worker_count = MAX2((max_wasted_regions_allowed * 2) , 1u);
uint heap_waste_worker_limit = MIN2(waste_worker_count, max_worker_count);
// Also consider HeapSizePerGCThread by calling AdaptiveSizePolicy to calculate
// the number of workers.
uint current_active_workers = heap->workers()->active_workers();
uint adaptive_worker_limit = AdaptiveSizePolicy::calc_active_workers(max_worker_count, current_active_workers, 0);
// Update active workers to the lower of the limits.
uint worker_count = MIN2(heap_waste_worker_limit, adaptive_worker_limit);
log_debug(gc, task)("Requesting %u active workers for full compaction (waste limited workers: %u, adaptive workers: %u)",
worker_count, heap_waste_worker_limit, adaptive_worker_limit);
worker_count = heap->workers()->update_active_workers(worker_count);
log_info(gc, task)("Using %u workers of %u for full compaction", worker_count, max_worker_count);
return worker_count;
}
G1FullCollector::G1FullCollector(G1CollectedHeap* heap, GCMemoryManager* memory_manager, bool explicit_gc, bool clear_soft_refs) :
_heap(heap),
_scope(memory_manager, explicit_gc, clear_soft_refs),
_num_workers(heap->workers()->active_workers()),
_num_workers(calc_active_workers()),
_oop_queue_set(_num_workers),
_array_queue_set(_num_workers),
_preserved_marks_set(true),

2
src/hotspot/share/gc/g1/g1FullCollector.hpp
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@ -56,6 +56,8 @@ class G1FullCollector : StackObj {
G1IsAliveClosure _is_alive;
ReferenceProcessorIsAliveMutator _is_alive_mutator;
static uint calc_active_workers();
public:
G1FullCollector(G1CollectedHeap* heap, GCMemoryManager* memory_manager, bool explicit_gc, bool clear_soft_refs);
~G1FullCollector();

3
src/hotspot/share/gc/shared/adaptiveSizePolicy.hpp
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@ -1,5 +1,5 @@
/*
* Copyright (c) 2004, 2016, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 2004, 2018, 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
@ -355,6 +355,7 @@ class AdaptiveSizePolicy : public CHeapObj<mtGC> {
// For ParNew collections
// For PS scavenge and ParOld collections
// For G1 evacuation pauses (subject to update)
// For G1 Full GCs (subject to update)
// Other collection phases inherit the number of
// GC workers from the calls above. For example,
// a CMS parallel remark uses the same number of GC