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8245925: G1 allocates EDEN region after CDS has executed GC

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Reviewed-by: jiangli, minqi, tschatzl
This commit is contained in:
Ioi Lam 2020-06-14 01:19:48 -07:00
parent af83d6ab25
commit c82c50b2a2
7 changed files with 76 additions and 21 deletions
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5
src/hotspot/share/gc/g1/g1HeapVerifier.cpp
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@ -1,5 +1,5 @@
/*
* Copyright (c) 2016, 2019, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 2016, 2020, 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
@ -326,7 +326,7 @@ void G1HeapVerifier::verify_ready_for_archiving() {
if (cl.has_holes()) {
log_warning(gc, verify)("All free regions should be at the top end of the heap, but"
" we found holes. This is probably caused by (unmovable) humongous"
" allocations, and may lead to fragmentation while"
" allocations or active GCLocker, and may lead to fragmentation while"
" writing archive heap memory regions.");
}
if (cl.has_humongous()) {
@ -334,7 +334,6 @@ void G1HeapVerifier::verify_ready_for_archiving() {
" may lead to fragmentation while"
" writing archive heap memory regions.");
}
assert(!cl.has_unexpected_holes(), "all holes should have been caused by humongous regions");
}
class VerifyArchivePointerRegionClosure: public HeapRegionClosure {

1
src/hotspot/share/gc/shared/collectedHeap.cpp
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@ -240,6 +240,7 @@ void CollectedHeap::collect_as_vm_thread(GCCause::Cause cause) {
do_full_collection(false); // don't clear all soft refs
break;
}
case GCCause::_archive_time_gc:
case GCCause::_metadata_GC_clear_soft_refs: {
HandleMark hm;
do_full_collection(true); // do clear all soft refs

20
src/hotspot/share/memory/heapShared.cpp
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@ -28,6 +28,7 @@
#include "classfile/symbolTable.hpp"
#include "classfile/systemDictionaryShared.hpp"
#include "classfile/vmSymbols.hpp"
#include "gc/shared/gcLocker.hpp"
#include "logging/log.hpp"
#include "logging/logMessage.hpp"
#include "logging/logStream.hpp"
@ -186,6 +187,25 @@ void HeapShared::archive_klass_objects(Thread* THREAD) {
}
}
void HeapShared::run_full_gc_in_vm_thread() {
if (is_heap_object_archiving_allowed()) {
// Avoid fragmentation while archiving heap objects.
// We do this inside a safepoint, so that no further allocation can happen after GC
// has finished.
if (GCLocker::is_active()) {
// Just checking for safety ...
// This should not happen during -Xshare:dump. If you see this, probably the Java core lib
// has been modified such that JNI code is executed in some clean up threads after
// we have finished class loading.
log_warning(cds)("GC locker is held, unable to start extra compacting GC. This may produce suboptimal results.");
} else {
log_info(cds)("Run GC ...");
Universe::heap()->collect_as_vm_thread(GCCause::_archive_time_gc);
log_info(cds)("Run GC done");
}
}
}
void HeapShared::archive_java_heap_objects(GrowableArray<MemRegion> *closed,
GrowableArray<MemRegion> *open) {
if (!is_heap_object_archiving_allowed()) {

2
src/hotspot/share/memory/heapShared.hpp
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@ -277,6 +277,8 @@ private:
#endif // INCLUDE_CDS_JAVA_HEAP
public:
static void run_full_gc_in_vm_thread() NOT_CDS_JAVA_HEAP_RETURN;
static bool is_heap_object_archiving_allowed() {
CDS_JAVA_HEAP_ONLY(return (UseG1GC && UseCompressedOops && UseCompressedClassPointers);)
NOT_CDS_JAVA_HEAP(return false;)

10
src/hotspot/share/memory/metaspaceShared.cpp
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@ -1638,6 +1638,7 @@ void VM_PopulateDumpSharedSpace::relocate_to_requested_base_address(CHeapBitMap*
}
void VM_PopulateDumpSharedSpace::doit() {
HeapShared::run_full_gc_in_vm_thread();
CHeapBitMap ptrmap;
MetaspaceShared::initialize_ptr_marker(&ptrmap);
@ -1956,14 +1957,9 @@ void MetaspaceShared::preload_and_dump(TRAPS) {
link_and_cleanup_shared_classes(CATCH);
log_info(cds)("Rewriting and linking classes: done");
if (HeapShared::is_heap_object_archiving_allowed()) {
// Avoid fragmentation while archiving heap objects.
Universe::heap()->soft_ref_policy()->set_should_clear_all_soft_refs(true);
Universe::heap()->collect(GCCause::_archive_time_gc);
Universe::heap()->soft_ref_policy()->set_should_clear_all_soft_refs(false);
}
VM_PopulateDumpSharedSpace op;
MutexLocker ml(THREAD, HeapShared::is_heap_object_archiving_allowed() ?
Heap_lock : NULL); // needed by HeapShared::run_gc()
VMThread::execute(&op);
}
}

10
test/hotspot/jtreg/runtime/cds/appcds/javaldr/GCDuringDump.java
View File

@ -1,5 +1,5 @@
/*
* Copyright (c) 2017, 2019, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 2017, 2020, 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
@ -41,6 +41,7 @@ public class GCDuringDump {
};
public static String agentClasses[] = {
GCDuringDumpTransformer.class.getName(),
GCDuringDumpTransformer.MyCleaner.class.getName(),
};
public static void main(String[] args) throws Throwable {
@ -55,15 +56,18 @@ public class GCDuringDump {
String gcLog = Boolean.getBoolean("test.cds.verbose.gc") ?
"-Xlog:gc*=info,gc+region=trace,gc+alloc+region=debug" : "-showversion";
for (int i=0; i<2; i++) {
for (int i=0; i<3; i++) {
// i = 0 -- run without agent = no extra GCs
// i = 1 -- run with agent = cause extra GCs
// i = 2 -- run with agent = cause extra GCs + use java.lang.ref.Cleaner
String extraArg = (i == 0) ? "-showversion" : "-javaagent:" + agentJar;
String extraOption = (i == 0) ? "-showversion" : "-XX:+AllowArchivingWithJavaAgent";
String extraOption2 = (i != 2) ? "-showversion" : "-Dtest.with.cleaner=true";
TestCommon.testDump(appJar, TestCommon.list(Hello.class.getName()),
"-XX:+UnlockDiagnosticVMOptions", extraOption,
"-XX:+UnlockDiagnosticVMOptions", extraOption, extraOption2,
"-Xlog:exceptions=trace",
extraArg, "-Xmx32m", gcLog);
TestCommon.run(

49
test/hotspot/jtreg/runtime/cds/appcds/javaldr/GCDuringDumpTransformer.java
View File

@ -1,5 +1,5 @@
/*
* Copyright (c) 2017, 2019, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 2017, 2020, 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
@ -25,18 +25,40 @@
import java.lang.instrument.ClassFileTransformer;
import java.lang.instrument.Instrumentation;
import java.lang.instrument.IllegalClassFormatException;
import java.lang.ref.Cleaner;
import java.security.ProtectionDomain;
public class GCDuringDumpTransformer implements ClassFileTransformer {
static boolean TEST_WITH_CLEANER = Boolean.getBoolean("test.with.cleaner");
static Cleaner cleaner;
static Thread thread;
static Object garbage;
static {
if (TEST_WITH_CLEANER) {
cleaner = Cleaner.create();
garbage = new Object();
cleaner.register(garbage, new MyCleaner());
System.out.println("Registered cleaner");
}
}
public byte[] transform(ClassLoader loader, String name, Class<?> classBeingRedefined,
ProtectionDomain pd, byte[] buffer) throws IllegalClassFormatException {
try {
makeGarbage();
} catch (Throwable t) {
t.printStackTrace();
if (TEST_WITH_CLEANER) {
if (name.equals("Hello")) {
garbage = null;
System.out.println("Unreferenced GCDuringDumpTransformer.garbage");
}
} else {
try {
Thread.sleep(200); // let GC to have a chance to run
} catch (Throwable t2) {}
makeGarbage();
} catch (Throwable t) {
t.printStackTrace();
try {
Thread.sleep(200); // let GC to have a chance to run
} catch (Throwable t2) {}
}
}
return null;
@ -45,7 +67,7 @@ public class GCDuringDumpTransformer implements ClassFileTransformer {
private static Instrumentation savedInstrumentation;
public static void premain(String agentArguments, Instrumentation instrumentation) {
System.out.println("ClassFileTransformer.premain() is called");
System.out.println("ClassFileTransformer.premain() is called: TEST_WITH_CLEANER = " + TEST_WITH_CLEANER);
instrumentation.addTransformer(new GCDuringDumpTransformer(), /*canRetransform=*/true);
savedInstrumentation = instrumentation;
}
@ -63,4 +85,15 @@ public class GCDuringDumpTransformer implements ClassFileTransformer {
Object[] a = new Object[10000];
}
}
static class MyCleaner implements Runnable {
static int count = 0;
int i = count++;
public void run() {
// Allocate something. This will cause G1 to allocate an EDEN region.
// See JDK-8245925
Object o = new Object();
System.out.println("cleaning " + i);
}
}
}