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8210559: ClassLoaderData Symbols can leak

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Unrefcount the symbol names when the CLD is destroyed

Reviewed-by: lfoltan, jiangli, iklam
This commit is contained in:
Coleen Phillimore 2018-09-14 12:10:28 -04:00
parent b16e5584ab
commit bad4a92e55
5 changed files with 31 additions and 4 deletions
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8
src/hotspot/share/classfile/classLoaderData.cpp
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@ -769,6 +769,14 @@ ClassLoaderData::~ClassLoaderData() {
if (_deallocate_list != NULL) {
delete _deallocate_list;
}
// Decrement refcounts of Symbols if created.
if (_name != NULL) {
_name->decrement_refcount();
}
if (_name_and_id != NULL) {
_name_and_id->decrement_refcount();
}
}
// Returns true if this class loader data is for the app class loader

11
src/hotspot/share/prims/whitebox.cpp
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@ -178,6 +178,15 @@ WB_ENTRY(jboolean, WB_IsClassAlive(JNIEnv* env, jobject target, jstring name))
return closure.found();
WB_END
WB_ENTRY(jint, WB_GetSymbolRefcount(JNIEnv* env, jobject unused, jstring name))
oop h_name = JNIHandles::resolve(name);
if (h_name == NULL) return false;
Symbol* sym = java_lang_String::as_symbol(h_name, CHECK_0);
TempNewSymbol tsym(sym); // Make sure to decrement reference count on sym on return
return (jint)sym->refcount();
WB_END
WB_ENTRY(void, WB_AddToBootstrapClassLoaderSearch(JNIEnv* env, jobject o, jstring segment)) {
#if INCLUDE_JVMTI
ResourceMark rm;
@ -1982,7 +1991,6 @@ WB_ENTRY(jint, WB_ProtectionDomainRemovedCount(JNIEnv* env, jobject o))
return (jint) SystemDictionary::pd_cache_table()->removed_entries_count();
WB_END
#define CC (char*)
static JNINativeMethod methods[] = {
@ -1996,6 +2004,7 @@ static JNINativeMethod methods[] = {
{CC"getHeapSpaceAlignment", CC"()J", (void*)&WB_GetHeapSpaceAlignment},
{CC"getHeapAlignment", CC"()J", (void*)&WB_GetHeapAlignment},
{CC"isClassAlive0", CC"(Ljava/lang/String;)Z", (void*)&WB_IsClassAlive },
{CC"getSymbolRefcount", CC"(Ljava/lang/String;)I", (void*)&WB_GetSymbolRefcount },
{CC"parseCommandLine0",
CC"(Ljava/lang/String;C[Lsun/hotspot/parser/DiagnosticCommand;)[Ljava/lang/Object;",
(void*) &WB_ParseCommandLine

11
test/hotspot/jtreg/runtime/ClassUnload/UnloadTest.java
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@ -23,6 +23,7 @@
/*
* @test UnloadTest
* @bug 8210559
* @requires vm.opt.final.ClassUnloading
* @modules java.base/jdk.internal.misc
* @library /runtime/testlibrary /test/lib
@ -30,7 +31,7 @@
* @build sun.hotspot.WhiteBox test.Empty
* @run driver ClassFileInstaller sun.hotspot.WhiteBox
* sun.hotspot.WhiteBox$WhiteBoxPermission
* @run main/othervm -Xbootclasspath/a:. -Xmn8m -XX:+UnlockDiagnosticVMOptions -XX:+WhiteBoxAPI UnloadTest
* @run main/othervm -Xbootclasspath/a:. -Xmn8m -XX:+UnlockDiagnosticVMOptions -XX:+WhiteBoxAPI -Xlog:class+unload=debug UnloadTest
*/
import sun.hotspot.WhiteBox;
@ -60,8 +61,16 @@ public class UnloadTest {
ClassUnloadCommon.failIf(!wb.isClassAlive(className), "should be live here");
String loaderName = cl.getName();
int loadedRefcount = wb.getSymbolRefcount(loaderName);
System.out.println("Refcount of symbol " + loaderName + " is " + loadedRefcount);
cl = null; c = null; o = null;
ClassUnloadCommon.triggerUnloading();
ClassUnloadCommon.failIf(wb.isClassAlive(className), "should have been unloaded");
int unloadedRefcount = wb.getSymbolRefcount(loaderName);
System.out.println("Refcount of symbol " + loaderName + " is " + unloadedRefcount);
ClassUnloadCommon.failIf(unloadedRefcount != (loadedRefcount - 1), "Refcount must be decremented");
}
}

4
test/hotspot/jtreg/runtime/testlibrary/ClassUnloadCommon.java
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@ -1,5 +1,5 @@
/*
* Copyright (c) 2013, 2016, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 2013, 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
@ -73,7 +73,7 @@ public class ClassUnloadCommon {
.map(Paths::get)
.map(ClassUnloadCommon::toURL)
.toArray(URL[]::new);
return new URLClassLoader(urls) {
return new URLClassLoader("ClassUnloadCommonClassLoader", urls, new ClassUnloadCommon().getClass().getClassLoader()) {
@Override
public Class<?> loadClass(String cn, boolean resolve)
throws ClassNotFoundException

1
test/lib/sun/hotspot/WhiteBox.java
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@ -103,6 +103,7 @@ public class WhiteBox {
return isClassAlive0(name.replace('.', '/'));
}
private native boolean isClassAlive0(String name);
public native int getSymbolRefcount(String name);
private native boolean isMonitorInflated0(Object obj);
public boolean isMonitorInflated(Object obj) {