JDK-7121600 : Instrumentation.redefineClasses() leaks class bytes
  • Type: Bug
  • Component: core-svc
  • Sub-Component: java.lang.instrument
  • Affected Version: 6
  • Priority: P2
  • Status: Closed
  • Resolution: Fixed
  • OS: generic
  • CPU: generic
  • Submitted: 2011-12-14
  • Updated: 2014-01-15
  • Resolved: 2012-01-10
The Version table provides details related to the release that this issue/RFE will be addressed.

Unresolved : Release in which this issue/RFE will be addressed.
Resolved: Release in which this issue/RFE has been resolved.
Fixed : Release in which this issue/RFE has been fixed. The release containing this fix may be available for download as an Early Access Release or a General Availability Release.

To download the current JDK release, click here.
JDK 6 JDK 7 JDK 8
6u60Fixed 7u4Fixed 8 b21Fixed
Related Reports
Relates :  
JDK-8019845 - NPG: Memory leak during class redefinition
Relates :  
JDK-7122253 - Instrumentation.retransformClasses() leaks class bytes
Relates :  
JDK-7124706 - enable RetransformBigClass.sh test when fix for 8013063 is promoted
Description
java.lang.instrument.Instrumentation.redefineClasses() leaks
class bytes for the redefined class or classes.

As part of the work on this bug, the following SDK/JDK test
will be added:

    java/lang/instrument/RedefineBigClass.sh
The attached RedefineBigClass.server.jtr.00 tells the tale
for the Server VM on Solaris X86. Version info is:

java version "1.6.0_29"
Java(TM) SE Runtime Environment (build 1.6.0_29-b11)
Java HotSpot(TM) Server VM (build 20.4-b02, mixed mode)


Here is trace info for the first RedefineClasses() call:

RedefineClasses-0x1: loading name=BigClass (avail_mem=323700K)
RedefineClasses-0x1: loaded name=BigClass (avail_mem=321536K)
RedefineClasses-0x1: redefined name=BigClass, count=1 (avail_mem=321504K)


Here is trace info for the last RedefineClasses() call:

RedefineClasses-0x1: loading name=BigClass (avail_mem=106516K)
RedefineClasses-0x1: loaded name=BigClass (avail_mem=106456K)
RedefineClasses-0x1: redefined name=BigClass, count=1000 (avail_mem=106456K)


Here's the math for leak:

321504 - 106456
215048
. / 1024
210.0078
. / 1024
.2050

Don't know why but the Server VM leaked way less than the Client VM
in this run.
The attached RedefineBigClass.client.jtr.00 tells the tale
for the Client VM on Solaris X86. Version info is:

java version "1.6.0_29"
Java(TM) SE Runtime Environment (build 1.6.0_29-b11)
Java HotSpot(TM) Client VM (build 20.4-b02, mixed mode)


Here is trace info for the first RedefineClasses() call:

RedefineClasses-0x1: loading name=BigClass (avail_mem=1185256K)
RedefineClasses-0x1: loaded name=BigClass (avail_mem=1184172K)
RedefineClasses-0x1: redefined name=BigClass, count=1 (avail_mem=1184140K)


Here is trace info for the last RedefineClasses() call:

RedefineClasses-0x1: loading name=BigClass (avail_mem=138252K)
RedefineClasses-0x1: loaded name=BigClass (avail_mem=138252K)
RedefineClasses-0x1: redefined name=BigClass, count=1000 (avail_mem=138252K)


Here's the math for leak:

1184140 - 138252
1045888
. / 1024
1021.3750
. / 1024
.9974

So we leaked almost 1GB in 1000 RedefineClasses() calls.
I did another Server VM run:

Here is trace info for the first RedefineClasses() call:

RedefineClasses-0x1: loading name=BigClass (avail_mem=1767152K)
RedefineClasses-0x1: loaded name=BigClass (avail_mem=1764988K)
RedefineClasses-0x1: redefined name=BigClass, count=1 (avail_mem=1764956K)


Here is trace info for the last RedefineClasses() call:

RedefineClasses-0x1: loading name=BigClass (avail_mem=640444K)
RedefineClasses-0x1: loaded name=BigClass (avail_mem=640388K)
RedefineClasses-0x1: redefined name=BigClass, count=1000 (avail_mem=640388K)


Here's the math:

1764956 - 640388
1124568
. / 1024
1098.2109
. / 1024
1.0724

So we leaked more than 1GB in 1000 RedefineClasses() calls.
Not sure at all what happened in the other Server run.
Comments
SUGGESTED FIX Minor changes made during Code Review round 1: $ diff -c src/share/instrument/JPLISAgent.c{.cr1,} *** src/share/instrument/JPLISAgent.c.cr1 Tue Dec 20 09:39:38 2011 --- src/share/instrument/JPLISAgent.c Wed Dec 21 14:40:34 2011 *************** *** 1209,1215 **** createAndThrowThrowableFromJVMTIErrorCode(jnienv, JVMTI_ERROR_OUT_OF_MEMORY); } ! if (!errorOccurred) { /* * We have to save the targetFile values that we compute so * that we can release the class_bytes arrays that are --- 1209,1215 ---- createAndThrowThrowableFromJVMTIErrorCode(jnienv, JVMTI_ERROR_OUT_OF_MEMORY); } ! else { /* * We have to save the targetFile values that we compute so * that we can release the class_bytes arrays that are *************** *** 1308,1316 **** if (!errorOccurred) { errorOccurred = checkForThrowable(jnienv); jplis_assert(!errorOccurred); - if (errorOccurred) { - break; - } } } } --- 1308,1313 ---- $ diff -c test/java/lang/instrument/RetransformBigClass.sh{.cr1,} *** test/java/lang/instrument/RetransformBigClass.sh.cr1 Tue Dec 20 15:35:49 2011 --- test/java/lang/instrument/RetransformBigClass.sh Thu Dec 22 18:25:35 2011 *************** *** 23,28 **** --- 23,29 ---- # @test # @bug 7122253 + # @ignore until the fix for 7122253 (from HotSpot) is in a promoted build # @summary Retransform a big class. # @author Daniel D. Daugherty #
23-12-2011
EVALUATION Changeset: 3c1ab134db71 Author: dcubed Date: 2011-12-22 18:35 -0800 URL: http://hg.openjdk.java.net/jdk8/tl/jdk/rev/3c1ab134db71 7121600: Instrumentation.redefineClasses() leaks class bytes Summary: Call JNI ReleaseByteArrayElements() on memory returned by JNI GetByteArrayElements(). Also push test for 7122253. Reviewed-by: acorn, poonam ! src/share/instrument/JPLISAgent.c + test/java/lang/instrument/BigClass.java + test/java/lang/instrument/MakeJAR4.sh + test/java/lang/instrument/RedefineBigClass.sh + test/java/lang/instrument/RedefineBigClassAgent.java + test/java/lang/instrument/RedefineBigClassApp.java + test/java/lang/instrument/RetransformBigClass.sh + test/java/lang/instrument/RetransformBigClassAgent.java + test/java/lang/instrument/RetransformBigClassApp.java Note that the RetransformBigClass.sh test is for 7122253. It is disabled in this push and should remain disabled until the fix for 7122253 is in a promoted build.
23-12-2011
SUGGESTED FIX The proposed fix for code review round 1 is attached as 7121600-webrev-cr1.tgz. This archive contains webrevs for JDK6u29, JDK7u4 and JDK8.
22-12-2011
PUBLIC COMMENTS I went back to the JDK1.5.0 FCS/GA source coode and found that the j2se/src/share/instrument/JPLISAgent.c source for the redefineClasses(JNIEnv * jnienv, JPLISAgent * agent, jobjectArray classDefinitions) is unchanged since revision 1.1: D 1.1 03/08/16 10:43:00 rfield 1 0 01256/00000/00000 MRs: COMMENTS: date and time created 03/08/16 10:43:00 by rfield Here's the code in 'sccs get -p -m' format: 1.1 /* 1.1 * Java code must not call this with a null list or a zero-length list. 1.1 */ 1.1 void 1.1 redefineClasses(JNIEnv * jnienv, JPLISAgent * agent, jobjectArray classDefinitions) { 1.1 jvmtiEnv* jvmtienv = agent->mJVMTIEnv; 1.1 jboolean errorOccurred = JNI_FALSE; 1.1 jclass classDefClass = NULL; 1.1 jmethodID getDefinitionClassMethodID = NULL; 1.1 jmethodID getDefinitionClassFileMethodID = NULL; 1.1 jvmtiClassDefinition* classDefs = NULL; 1.1 jsize numDefs = 0; 1.1 1.1 jplis_assert(classDefinitions != NULL); 1.1 1.1 numDefs = (*jnienv)->GetArrayLength(jnienv, classDefinitions); 1.1 errorOccurred = checkForThrowable(jnienv); 1.1 jplis_assert(!errorOccurred); 1.1 1.1 if (!errorOccurred) { 1.1 jplis_assert(numDefs > 0); 1.1 /* get method IDs for methods to call on class definitions */ 1.1 classDefClass = (*jnienv)->FindClass(jnienv, "java/lang/instrument/ClassDefinition"); 1.1 errorOccurred = checkForThrowable(jnienv); 1.1 jplis_assert(!errorOccurred); 1.1 } 1.1 1.1 if (!errorOccurred) { 1.1 getDefinitionClassMethodID = (*jnienv)->GetMethodID( jnienv, 1.1 classDefClass, 1.1 "getDefinitionClass", 1.1 "()Ljava/lang/Class;"); 1.1 errorOccurred = checkForThrowable(jnienv); 1.1 jplis_assert(!errorOccurred); 1.1 } 1.1 1.1 if (!errorOccurred) { 1.1 getDefinitionClassFileMethodID = (*jnienv)->GetMethodID( jnienv, 1.1 classDefClass, 1.1 "getDefinitionClassFile", 1.1 "()[B"); 1.1 errorOccurred = checkForThrowable(jnienv); 1.1 jplis_assert(!errorOccurred); 1.1 } 1.1 1.1 if (!errorOccurred) { 1.1 classDefs = (jvmtiClassDefinition *) allocate( 1.1 jvmtienv, 1.1 numDefs * sizeof(jvmtiClassDefinition)); 1.1 errorOccurred = (classDefs == NULL); 1.1 jplis_assert(!errorOccurred); 1.1 if ( errorOccurred ) { 1.1 createAndThrowThrowableFromJVMTIErrorCode(jnienv, JVMTI_ERROR_OUT_OF_MEMORY); 1.1 } 1.1 else { 1.1 jint i; 1.1 for (i = 0; i < numDefs; i++) { 1.1 jclass classDef = NULL; 1.1 jbyteArray targetFile = NULL; 1.1 1.1 classDef = (*jnienv)->GetObjectArrayElement(jnienv, classDefinitions, i); 1.1 errorOccurred = checkForThrowable(jnienv); 1.1 jplis_assert(!errorOccurred); 1.1 if (errorOccurred) { 1.1 break; 1.1 } 1.1 1.1 classDefs[i].klass = (*jnienv)->CallObjectMethod(jnienv, classDef, getDefinitionClassMethodID); 1.1 errorOccurred = checkForThrowable(jnienv); 1.1 jplis_assert(!errorOccurred); 1.1 if (errorOccurred) { 1.1 break; 1.1 } 1.1 1.1 targetFile = (*jnienv)->CallObjectMethod(jnienv, classDef, getDefinitionClassFileMethodID); 1.1 errorOccurred = checkForThrowable(jnienv); 1.1 jplis_assert(!errorOccurred); 1.1 if (errorOccurred) { 1.1 break; 1.1 } 1.1 1.1 classDefs[i].class_bytes = (unsigned char*)(*jnienv)->GetByteArrayElements(jnienv, targetFile, NULL); 1.1 errorOccurred = checkForThrowable(jnienv); 1.1 jplis_assert(!errorOccurred); 1.1 if (errorOccurred) { 1.1 break; 1.1 } 1.1 1.1 classDefs[i].class_byte_count = (*jnienv)->GetArrayLength(jnienv, targetFile); 1.1 errorOccurred = checkForThrowable(jnienv); 1.1 jplis_assert(!errorOccurred); 1.1 if (errorOccurred) { 1.1 break; 1.1 } 1.1 } 1.1 1.1 if (!errorOccurred) { 1.1 jvmtiError errorCode = JVMTI_ERROR_NONE; 1.1 errorCode = (*jvmtienv)->RedefineClasses(jvmtienv, numDefs, classDefs); 1.1 errorOccurred = (errorCode != JVMTI_ERROR_NONE); 1.1 if ( errorOccurred ) { 1.1 createAndThrowThrowableFromJVMTIErrorCode(jnienv, errorCode); 1.1 } 1.1 } 1.1 1.1 /* Give back the buffer if we allocated it. 1.1 */ 1.1 deallocate(jvmtienv, classDefs); 1.1 } 1.1 } 1.1 1.1 mapThrownThrowableIfNecessary(jnienv, redefineClassMapper); 1.1 } I don't know which JDK5 build included the JLI/JPLIS push so I'm using 5.0-B64 which is the FCS/GA build.
20-12-2011
SUGGESTED FIX The proposed fix for code review round 0 is attached as 7121600-webrev-cr0.tgz. Update: The proposed fix for code review round 0 solves the memory leak bug but not properly handle error conditions.
14-12-2011
EVALUATION The class bytes are extracted from their Java representation via a JNI GetByteArrayElements() call. That method can make a copy of the data and the copy must be released via a JNI ReleaseByteArrayElements().
14-12-2011