| /* |
| * Copyright (c) 2019, Oracle and/or its affiliates. All rights reserved. |
| * Copyright (c) 2019, Google 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 |
| * under the terms of the GNU General Public License version 2 only, as |
| * published by the Free Software Foundation. |
| * |
| * This code is distributed in the hope that it will be useful, but WITHOUT |
| * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| * version 2 for more details (a copy is included in the LICENSE file that |
| * accompanied this code). |
| * |
| * You should have received a copy of the GNU General Public License version |
| * 2 along with this work; if not, write to the Free Software Foundation, |
| * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| * |
| * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
| * or visit www.oracle.com if you need additional information or have any |
| * questions. |
| * |
| */ |
| |
| #include "precompiled.hpp" |
| #include "gc/shared/gcOverheadChecker.hpp" |
| #include "gc/shared/softRefPolicy.hpp" |
| #include "logging/log.hpp" |
| |
| GCOverheadChecker::GCOverheadChecker() : |
| _gc_overhead_limit_exceeded(false), |
| _print_gc_overhead_limit_would_be_exceeded(false), |
| _gc_overhead_limit_count(0) { |
| assert(GCOverheadLimitThreshold > 0, |
| "No opportunity to clear SoftReferences before GC overhead limit"); |
| } |
| |
| void GCOverheadChecker::check_gc_overhead_limit(GCOverheadTester* time_overhead, |
| GCOverheadTester* space_overhead, |
| bool is_full_gc, |
| GCCause::Cause gc_cause, |
| SoftRefPolicy* soft_ref_policy) { |
| |
| // Ignore explicit GC's. Exiting here does not set the flag and |
| // does not reset the count. |
| if (GCCause::is_user_requested_gc(gc_cause) || |
| GCCause::is_serviceability_requested_gc(gc_cause)) { |
| return; |
| } |
| |
| bool print_gc_overhead_limit_would_be_exceeded = false; |
| if (is_full_gc) { |
| if (time_overhead->is_exceeded() && space_overhead->is_exceeded()) { |
| // Collections, on average, are taking too much time, and |
| // we have too little space available after a full gc. |
| // At this point the GC overhead limit is being exceeded. |
| _gc_overhead_limit_count++; |
| if (UseGCOverheadLimit) { |
| if (_gc_overhead_limit_count >= GCOverheadLimitThreshold){ |
| // All conditions have been met for throwing an out-of-memory |
| set_gc_overhead_limit_exceeded(true); |
| // Avoid consecutive OOM due to the gc time limit by resetting |
| // the counter. |
| reset_gc_overhead_limit_count(); |
| } else { |
| // The required consecutive collections which exceed the |
| // GC time limit may or may not have been reached. We |
| // are approaching that condition and so as not to |
| // throw an out-of-memory before all SoftRef's have been |
| // cleared, set _should_clear_all_soft_refs in SoftRefPolicy. |
| // The clearing will be done on the next GC. |
| bool near_limit = gc_overhead_limit_near(); |
| if (near_limit) { |
| soft_ref_policy->set_should_clear_all_soft_refs(true); |
| log_trace(gc, ergo)("Nearing GC overhead limit, will be clearing all SoftReference"); |
| } |
| } |
| } |
| // Set this even when the overhead limit will not |
| // cause an out-of-memory. Diagnostic message indicating |
| // that the overhead limit is being exceeded is sometimes |
| // printed. |
| print_gc_overhead_limit_would_be_exceeded = true; |
| |
| } else { |
| // Did not exceed overhead limits |
| reset_gc_overhead_limit_count(); |
| } |
| } |
| |
| if (UseGCOverheadLimit) { |
| if (gc_overhead_limit_exceeded()) { |
| log_trace(gc, ergo)("GC is exceeding overhead limit of " UINTX_FORMAT "%%", GCTimeLimit); |
| reset_gc_overhead_limit_count(); |
| } else if (print_gc_overhead_limit_would_be_exceeded) { |
| assert(_gc_overhead_limit_count > 0, "Should not be printing"); |
| log_trace(gc, ergo)("GC would exceed overhead limit of " UINTX_FORMAT "%% %d consecutive time(s)", |
| GCTimeLimit, _gc_overhead_limit_count); |
| } |
| } |
| } |