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8159978: Use an array to store the collection set regions instead of linking through regions
Fix a potential problem with memory visibility in the sampling thread in the collection set by changing the way we store the collection set. Reviewed-by: ehelin, jmasa
This commit is contained in:
Thomas Schatzl
parent
9a3dc1d8cc
commit
7fd90042ca
15 changed files with 404 additions and 473 deletions
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@ -30,6 +30,7 @@
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#include "gc/g1/heapRegion.inline.hpp"
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#include "gc/g1/heapRegionRemSet.hpp"
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#include "gc/g1/heapRegionSet.hpp"
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#include "logging/logStream.hpp"
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#include "utilities/debug.hpp"
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G1CollectorState* G1CollectionSet::collector_state() {
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@ -55,48 +56,63 @@ G1CollectionSet::G1CollectionSet(G1CollectedHeap* g1h, G1Policy* policy) :
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_eden_region_length(0),
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_survivor_region_length(0),
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_old_region_length(0),
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_head(NULL),
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_bytes_used_before(0),
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_recorded_rs_lengths(0),
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_collection_set_regions(NULL),
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_collection_set_cur_length(0),
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_collection_set_max_length(0),
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// Incremental CSet attributes
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_inc_build_state(Inactive),
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_inc_head(NULL),
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_inc_tail(NULL),
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_inc_bytes_used_before(0),
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_inc_recorded_rs_lengths(0),
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_inc_recorded_rs_lengths_diffs(0),
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_inc_predicted_elapsed_time_ms(0.0),
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_inc_predicted_elapsed_time_ms_diffs(0.0),
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_inc_region_length(0) {}
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_inc_predicted_elapsed_time_ms_diffs(0.0) {
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}
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G1CollectionSet::~G1CollectionSet() {
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if (_collection_set_regions != NULL) {
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FREE_C_HEAP_ARRAY(uint, _collection_set_regions);
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}
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delete _cset_chooser;
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}
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void G1CollectionSet::init_region_lengths(uint eden_cset_region_length,
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uint survivor_cset_region_length) {
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assert_at_safepoint(true);
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_eden_region_length = eden_cset_region_length;
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_survivor_region_length = survivor_cset_region_length;
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assert(young_region_length() == _inc_region_length, "should match %u == %u", young_region_length(), _inc_region_length);
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assert((size_t) young_region_length() == _collection_set_cur_length,
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"Young region length %u should match collection set length " SIZE_FORMAT, young_region_length(), _collection_set_cur_length);
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_old_region_length = 0;
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}
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void G1CollectionSet::initialize(uint max_region_length) {
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guarantee(_collection_set_regions == NULL, "Must only initialize once.");
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_collection_set_max_length = max_region_length;
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_collection_set_regions = NEW_C_HEAP_ARRAY(uint, max_region_length, mtGC);
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}
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void G1CollectionSet::set_recorded_rs_lengths(size_t rs_lengths) {
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_recorded_rs_lengths = rs_lengths;
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}
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// Add the heap region at the head of the non-incremental collection set
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void G1CollectionSet::add_old_region(HeapRegion* hr) {
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assert_at_safepoint(true);
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assert(_inc_build_state == Active, "Precondition");
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assert(hr->is_old(), "the region should be old");
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assert(!hr->in_collection_set(), "should not already be in the CSet");
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_g1->register_old_region_with_cset(hr);
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hr->set_next_in_collection_set(_head);
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_head = hr;
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_collection_set_regions[_collection_set_cur_length++] = hr->hrm_index();
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assert(_collection_set_cur_length <= _collection_set_max_length, "Collection set now larger than maximum size.");
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_bytes_used_before += hr->used();
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size_t rs_length = hr->rem_set()->occupied();
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_recorded_rs_lengths += rs_length;
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@ -105,12 +121,10 @@ void G1CollectionSet::add_old_region(HeapRegion* hr) {
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// Initialize the per-collection-set information
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void G1CollectionSet::start_incremental_building() {
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assert(_collection_set_cur_length == 0, "Collection set must be empty before starting a new collection set.");
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assert(_inc_build_state == Inactive, "Precondition");
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_inc_head = NULL;
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_inc_tail = NULL;
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_inc_bytes_used_before = 0;
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_inc_region_length = 0;
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_inc_recorded_rs_lengths = 0;
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_inc_recorded_rs_lengths_diffs = 0;
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@ -151,6 +165,38 @@ void G1CollectionSet::finalize_incremental_building() {
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_inc_predicted_elapsed_time_ms_diffs = 0.0;
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}
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void G1CollectionSet::clear() {
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assert_at_safepoint(true);
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_collection_set_cur_length = 0;
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}
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void G1CollectionSet::iterate(HeapRegionClosure* cl) const {
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iterate_from(cl, 0, 1);
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}
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void G1CollectionSet::iterate_from(HeapRegionClosure* cl, uint worker_id, uint total_workers) const {
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size_t len = _collection_set_cur_length;
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OrderAccess::loadload();
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if (len == 0) {
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return;
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}
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size_t start_pos = (worker_id * len) / total_workers;
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size_t cur_pos = start_pos;
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do {
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HeapRegion* r = G1CollectedHeap::heap()->region_at(_collection_set_regions[cur_pos]);
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bool result = cl->doHeapRegion(r);
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if (result) {
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cl->incomplete();
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return;
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}
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cur_pos++;
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if (cur_pos == len) {
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cur_pos = 0;
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}
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} while (cur_pos != start_pos);
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}
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void G1CollectionSet::update_young_region_prediction(HeapRegion* hr,
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size_t new_rs_length) {
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// Update the CSet information that is dependent on the new RS length
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@ -183,8 +229,16 @@ void G1CollectionSet::add_young_region_common(HeapRegion* hr) {
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assert(hr->is_young(), "invariant");
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assert(_inc_build_state == Active, "Precondition");
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hr->set_young_index_in_cset(_inc_region_length);
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_inc_region_length++;
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size_t collection_set_length = _collection_set_cur_length;
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assert(collection_set_length <= INT_MAX, "Collection set is too large with %d entries", (int)collection_set_length);
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hr->set_young_index_in_cset((int)collection_set_length);
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_collection_set_regions[collection_set_length] = hr->hrm_index();
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// Concurrent readers must observe the store of the value in the array before an
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// update to the length field.
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OrderAccess::storestore();
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_collection_set_cur_length++;
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assert(_collection_set_cur_length <= _collection_set_max_length, "Collection set larger than maximum allowed.");
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// This routine is used when:
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// * adding survivor regions to the incremental cset at the end of an
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@ -218,59 +272,81 @@ void G1CollectionSet::add_young_region_common(HeapRegion* hr) {
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assert(!hr->in_collection_set(), "invariant");
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_g1->register_young_region_with_cset(hr);
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assert(hr->next_in_collection_set() == NULL, "invariant");
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}
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// Add the region at the RHS of the incremental cset
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void G1CollectionSet::add_survivor_regions(HeapRegion* hr) {
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// We should only ever be appending survivors at the end of a pause
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assert(hr->is_survivor(), "Logic");
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// Do the 'common' stuff
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assert(hr->is_survivor(), "Must only add survivor regions, but is %s", hr->get_type_str());
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add_young_region_common(hr);
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// Now add the region at the right hand side
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if (_inc_tail == NULL) {
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assert(_inc_head == NULL, "invariant");
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_inc_head = hr;
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} else {
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_inc_tail->set_next_in_collection_set(hr);
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}
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_inc_tail = hr;
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}
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// Add the region to the LHS of the incremental cset
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void G1CollectionSet::add_eden_region(HeapRegion* hr) {
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// Survivors should be added to the RHS at the end of a pause
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assert(hr->is_eden(), "Logic");
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// Do the 'common' stuff
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assert(hr->is_eden(), "Must only add eden regions, but is %s", hr->get_type_str());
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add_young_region_common(hr);
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// Add the region at the left hand side
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hr->set_next_in_collection_set(_inc_head);
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if (_inc_head == NULL) {
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assert(_inc_tail == NULL, "Invariant");
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_inc_tail = hr;
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}
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_inc_head = hr;
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}
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#ifndef PRODUCT
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void G1CollectionSet::print(HeapRegion* list_head, outputStream* st) {
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assert(list_head == inc_head() || list_head == head(), "must be");
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class G1VerifyYoungAgesClosure : public HeapRegionClosure {
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public:
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bool _valid;
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public:
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G1VerifyYoungAgesClosure() : HeapRegionClosure(), _valid(true) { }
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st->print_cr("\nCollection_set:");
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HeapRegion* csr = list_head;
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while (csr != NULL) {
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HeapRegion* next = csr->next_in_collection_set();
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assert(csr->in_collection_set(), "bad CS");
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st->print_cr(" " HR_FORMAT ", P: " PTR_FORMAT "N: " PTR_FORMAT ", age: %4d",
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HR_FORMAT_PARAMS(csr),
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p2i(csr->prev_top_at_mark_start()), p2i(csr->next_top_at_mark_start()),
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csr->age_in_surv_rate_group_cond());
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csr = next;
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virtual bool doHeapRegion(HeapRegion* r) {
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guarantee(r->is_young(), "Region must be young but is %s", r->get_type_str());
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SurvRateGroup* group = r->surv_rate_group();
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if (group == NULL) {
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log_error(gc, verify)("## encountered NULL surv_rate_group in young region");
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_valid = false;
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}
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if (r->age_in_surv_rate_group() < 0) {
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log_error(gc, verify)("## encountered negative age in young region");
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_valid = false;
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}
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return false;
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}
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bool valid() const { return _valid; }
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};
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bool G1CollectionSet::verify_young_ages() {
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assert_at_safepoint(true);
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G1VerifyYoungAgesClosure cl;
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iterate(&cl);
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if (!cl.valid()) {
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LogStreamHandle(Error, gc, verify) log;
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print(&log);
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}
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return cl.valid();
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}
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class G1PrintCollectionSetClosure : public HeapRegionClosure {
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outputStream* _st;
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public:
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G1PrintCollectionSetClosure(outputStream* st) : HeapRegionClosure(), _st(st) { }
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virtual bool doHeapRegion(HeapRegion* r) {
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assert(r->in_collection_set(), "Region %u should be in collection set", r->hrm_index());
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_st->print_cr(" " HR_FORMAT ", P: " PTR_FORMAT "N: " PTR_FORMAT ", age: %4d",
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HR_FORMAT_PARAMS(r),
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p2i(r->prev_top_at_mark_start()),
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p2i(r->next_top_at_mark_start()),
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r->age_in_surv_rate_group_cond());
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return false;
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}
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};
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void G1CollectionSet::print(outputStream* st) {
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st->print_cr("\nCollection_set:");
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G1PrintCollectionSetClosure cl(st);
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iterate(&cl);
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}
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#endif // !PRODUCT
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@ -281,7 +357,6 @@ double G1CollectionSet::finalize_young_part(double target_pause_time_ms, G1Survi
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guarantee(target_pause_time_ms > 0.0,
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"target_pause_time_ms = %1.6lf should be positive", target_pause_time_ms);
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guarantee(_head == NULL, "Precondition");
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size_t pending_cards = _policy->pending_cards();
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double base_time_ms = _policy->predict_base_elapsed_time_ms(pending_cards);
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@ -305,7 +380,6 @@ double G1CollectionSet::finalize_young_part(double target_pause_time_ms, G1Survi
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// Clear the fields that point to the survivor list - they are all young now.
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survivors->convert_to_eden();
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_head = _inc_head;
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_bytes_used_before = _inc_bytes_used_before;
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time_remaining_ms = MAX2(time_remaining_ms - _inc_predicted_elapsed_time_ms, 0.0);
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@ -422,23 +496,41 @@ void G1CollectionSet::finalize_old_part(double time_remaining_ms) {
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}
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#ifdef ASSERT
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class G1VerifyYoungCSetIndicesClosure : public HeapRegionClosure {
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private:
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size_t _young_length;
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int* _heap_region_indices;
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public:
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G1VerifyYoungCSetIndicesClosure(size_t young_length) : HeapRegionClosure(), _young_length(young_length) {
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_heap_region_indices = NEW_C_HEAP_ARRAY(int, young_length, mtGC);
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for (size_t i = 0; i < young_length; i++) {
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_heap_region_indices[i] = -1;
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}
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}
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~G1VerifyYoungCSetIndicesClosure() {
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FREE_C_HEAP_ARRAY(int, _heap_region_indices);
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}
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virtual bool doHeapRegion(HeapRegion* r) {
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const int idx = r->young_index_in_cset();
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assert(idx > -1, "Young index must be set for all regions in the incremental collection set but is not for region %u.", r->hrm_index());
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assert((size_t)idx < _young_length, "Young cset index too large for region %u", r->hrm_index());
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assert(_heap_region_indices[idx] == -1,
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"Index %d used by multiple regions, first use by region %u, second by region %u",
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idx, _heap_region_indices[idx], r->hrm_index());
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_heap_region_indices[idx] = r->hrm_index();
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return false;
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}
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};
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void G1CollectionSet::verify_young_cset_indices() const {
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ResourceMark rm;
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uint* heap_region_indices = NEW_RESOURCE_ARRAY(uint, young_region_length());
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for (uint i = 0; i < young_region_length(); ++i) {
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heap_region_indices[i] = (uint)-1;
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}
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assert_at_safepoint(true);
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for (HeapRegion* hr = _inc_head; hr != NULL; hr = hr->next_in_collection_set()) {
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const int idx = hr->young_index_in_cset();
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assert(idx > -1, "must be set for all inc cset regions");
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assert((uint)idx < young_region_length(), "young cset index too large");
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assert(heap_region_indices[idx] == (uint)-1,
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"index %d used by multiple regions, first use by %u, second by %u",
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idx, heap_region_indices[idx], hr->hrm_index());
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heap_region_indices[idx] = hr->hrm_index();
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}
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G1VerifyYoungCSetIndicesClosure cl(_collection_set_cur_length);
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iterate(&cl);
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}
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#endif
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