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8195158: Concurrent System.gc() is "upgraded" to stop-the-world System.gc()

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Reviewed-by: sjohanss, eosterlund
This commit is contained in:
Erik Helin 2018-01-17 19:05:58 +01:00
parent fc1b01b9a2
commit 73388668cd
2 changed files with 65 additions and 7 deletions
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18
src/hotspot/share/gc/g1/vm_operations_g1.cpp
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@ -139,13 +139,17 @@ void VM_G1CollectForAllocation::doit() {
// An allocation had been requested. Do it, eventually trying a stronger
// kind of GC.
_result = g1h->satisfy_failed_allocation(_word_size, _allocation_context, &_pause_succeeded);
} else if (!g1h->has_regions_left_for_allocation()) {
// There has been a request to perform a GC to free some space. We have no
// information on how much memory has been asked for. In case there are
// absolutely no regions left to allocate into, do a maximally compacting full GC.
log_info(gc, ergo)("Attempting maximally compacting collection");
_pause_succeeded = g1h->do_full_collection(false, /* explicit gc */
true /* clear_all_soft_refs */);
} else {
bool should_upgrade_to_full = !g1h->should_do_concurrent_full_gc(_gc_cause) &&
!g1h->has_regions_left_for_allocation();
if (should_upgrade_to_full) {
// There has been a request to perform a GC to free some space. We have no
// information on how much memory has been asked for. In case there are
// absolutely no regions left to allocate into, do a maximally compacting full GC.
log_info(gc, ergo)("Attempting maximally compacting collection");
_pause_succeeded = g1h->do_full_collection(false, /* explicit gc */
true /* clear_all_soft_refs */);
}
}
guarantee(_pause_succeeded, "Elevated collections during the safepoint must always succeed.");
} else {

54
test/hotspot/jtreg/gc/g1/TestConcurrentSystemGC.java Normal file
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@ -0,0 +1,54 @@
/*
* Copyright (c) 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
* 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.
*/
/*
* @test TestConcurrentSystemGC
* @bug 8195158
* @summary Test that a System.gc() with -XX:+ExplicitGCInvokesConcurrent
* is *not* upgraded to STW full GC
* @key gc
* @requires vm.gc.G1
* @library /test/lib
* @modules java.base/jdk.internal.misc
* java.management
* @run main/othervm -XX:+UseG1GC -XX:+ExplicitGCInvokesConcurrent -Xmx8m -Xms8m -XX:G1HeapRegionSize=1m TestConcurrentSystemGC
*/
import java.util.ArrayList;
import java.util.List;
public class TestConcurrentSystemGC {
public static List<char[]> memory;
public static void main(String[] args) throws Exception {
memory = new ArrayList<>();
try {
while (true) {
memory.add(new char[1024 * 128]);
System.gc(); // should not trigger any assertions
}
} catch (OutOfMemoryError e) {
memory = null;
System.gc();
}
}
}