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8306695: Divide by zero in G1Policy::logged_cards_processing_time

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Reviewed-by: iwalulya, tschatzl
This commit is contained in:
Kim Barrett 2023-04-25 04:19:32 +00:00
parent 2471919020
commit 8063aa2e4a
1 changed files with 10 additions and 3 deletions

13
src/hotspot/share/gc/g1/g1Policy.cpp

@ -1,5 +1,5 @@
/*
* Copyright (c) 2001, 2022, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 2001, 2023, 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
@ -722,8 +722,15 @@ double G1Policy::logged_cards_processing_time() const {
size_t logged_dirty_cards = phase_times()->sum_thread_work_items(G1GCPhaseTimes::MergeLB, G1GCPhaseTimes::MergeLBDirtyCards);
size_t scan_heap_roots_cards = phase_times()->sum_thread_work_items(G1GCPhaseTimes::ScanHR, G1GCPhaseTimes::ScanHRScannedCards) +
phase_times()->sum_thread_work_items(G1GCPhaseTimes::OptScanHR, G1GCPhaseTimes::ScanHRScannedCards);
// This may happen if there are duplicate cards in different log buffers.
if (logged_dirty_cards > scan_heap_roots_cards) {
// Approximate the time spent processing cards from log buffers by scaling
// the total processing time by the ratio of logged cards to total cards
// processed. There might be duplicate cards in different log buffers,
// leading to an overestimate. That effect should be relatively small
// unless there are few cards to process, because cards in buffers are
// dirtied to limit duplication. Also need to avoid scaling when both
// counts are zero, which happens especially during early GCs. So ascribe
// all of the time to the logged cards unless there are more total cards.
if (logged_dirty_cards >= scan_heap_roots_cards) {
return all_cards_processing_time + average_time_ms(G1GCPhaseTimes::MergeLB);
}
return (all_cards_processing_time * logged_dirty_cards / scan_heap_roots_cards) + average_time_ms(G1GCPhaseTimes::MergeLB);