Memory leaks in classTrack.c classTrack_addPreparedClass() during debugging

Description of problem:

We observe a native memory leak when repeating JDI operations from Eclipse in a debuggee JVM.

jemalloc reports 2 different types of memory leaks in classTrack_addPreparedClass(), classTrack.c.:

[5888 bytes leaked]
je_prof_backtrace (/home/sandreev/git/misc/jemalloc/src/prof.c:636 (discriminator 2))
je_malloc_default (/home/sandreev/git/misc/jemalloc/src/jemalloc.c:2289)
os::malloc (/data/git/jdk11/src/hotspot/share/runtime/os.cpp:697)
os::malloc (/data/git/jdk11/src/hotspot/share/runtime/os.cpp:660 (discriminator 3))
JvmtiEnvBase::allocate (/data/git/jdk11/src/hotspot/share/prims/jvmtiEnvBase.hpp:195)
JvmtiEnvBase::jvmtiMalloc (/data/git/jdk11/src/hotspot/share/prims/jvmtiEnvBase.cpp:501)
JvmtiEnv::GetClassSignature (/data/git/jdk11/src/hotspot/share/prims/jvmtiEnv.cpp:2365)
jvmti_GetClassSignature (/data/git/jdk11/build/linux-x86_64-normal-server-slowdebug/hotspot/variant-server/gensrc/jvmtifiles/jvmtiEnter.cpp:3380)
classSignature (/data/git/jdk11/src/jdk.jdwp.agent/share/native/libjdwp/util.c:1235)
classTrack_addPreparedClass (/data/git/jdk11/src/jdk.jdwp.agent/share/native/libjdwp/classTrack.c:233)
event_callback (/data/git/jdk11/src/jdk.jdwp.agent/share/native/libjdwp/eventHandler.c:643)
cbClassPrepare (/data/git/jdk11/src/jdk.jdwp.agent/share/native/libjdwp/eventHandler.c:893)
JvmtiExport::post_class_prepare (/data/git/jdk11/src/hotspot/share/prims/jvmtiExport.cpp:1320)
InstanceKlass::link_class_impl (/data/git/jdk11/src/hotspot/share/oops/instanceKlass.cpp:839 (discriminator 1))
InstanceKlass::link_class (/data/git/jdk11/src/hotspot/share/oops/instanceKlass.cpp:698)
InstanceKlass::initialize_impl (/data/git/jdk11/src/hotspot/share/oops/instanceKlass.cpp:898)
InstanceKlass::initialize (/data/git/jdk11/src/hotspot/share/oops/instanceKlass.cpp:669)
InterpreterRuntime::_new (/data/git/jdk11/src/hotspot/share/interpreter/interpreterRuntime.cpp:240)
?? (??:0)

[5040 bytes leaked]
je_prof_backtrace (/home/sandreev/git/misc/jemalloc/src/prof.c:636 (discriminator 2))
je_malloc_default (/home/sandreev/git/misc/jemalloc/src/jemalloc.c:2289)
os::malloc (/data/git/jdk11/src/hotspot/share/runtime/os.cpp:697)
os::malloc (/data/git/jdk11/src/hotspot/share/runtime/os.cpp:660 (discriminator 3))
JvmtiEnvBase::allocate (/data/git/jdk11/src/hotspot/share/prims/jvmtiEnvBase.hpp:195)
JvmtiEnv::Allocate (/data/git/jdk11/src/hotspot/share/prims/jvmtiEnv.cpp:126)
jvmti_Allocate (/data/git/jdk11/build/linux-x86_64-normal-server-slowdebug/hotspot/variant-server/gensrc/jvmtifiles/jvmtiEnter.cpp:341)
jvmtiAllocate (/data/git/jdk11/src/jdk.jdwp.agent/share/native/libjdwp/util.c:1794)
classTrack_addPreparedClass (/data/git/jdk11/src/jdk.jdwp.agent/share/native/libjdwp/classTrack.c:229)
event_callback (/data/git/jdk11/src/jdk.jdwp.agent/share/native/libjdwp/eventHandler.c:643)
cbClassPrepare (/data/git/jdk11/src/jdk.jdwp.agent/share/native/libjdwp/eventHandler.c:893)
JvmtiExport::post_class_prepare (/data/git/jdk11/src/hotspot/share/prims/jvmtiExport.cpp:1320)
InstanceKlass::link_class_impl (/data/git/jdk11/src/hotspot/share/oops/instanceKlass.cpp:839 (discriminator 1))
InstanceKlass::link_class (/data/git/jdk11/src/hotspot/share/oops/instanceKlass.cpp:698)
InstanceKlass::initialize_impl (/data/git/jdk11/src/hotspot/share/oops/instanceKlass.cpp:898)
InstanceKlass::initialize (/data/git/jdk11/src/hotspot/share/oops/instanceKlass.cpp:669)
InterpreterRuntime::_new (/data/git/jdk11/src/hotspot/share/interpreter/interpreterRuntime.cpp:240)
?? (??:0)

Version-Release number of selected component (if applicable):

OpenJDK 11

How reproducible:

Run JDI operations with Eclipse in any Java program. E.g. can be done with a command handler:

public class SampleHandler extends AbstractHandler {

@Override
public Object execute(ExecutionEvent event) throws ExecutionException {
Job job = new Job("JDI operation") {
@Override
protected IStatus run(IProgressMonitor monitor) {
int n = 20 * 60;
for (int i = 0; i < n; ++i) {
try {
IJavaDebugTarget javaTarget = getFirstJavaDebugTarget();
if (javaTarget != null) {
IJavaThread javaThread = getFirstSuspendedJavaThread(javaTarget);
if (javaThread != null) {
IJavaType[] javaClass = javaTarget.getJavaTypes("java.lang.String");
if (javaClass[0] instanceof IJavaClassType) {
IJavaClassType jdiClassType = (IJavaClassType) javaClass[0];
IJavaObject instance = jdiClassType.newInstance("()V", null, javaThread);
try {
instance.disableCollection();
if (!monitor.isCanceled())

{ instance.sendMessage("isEmpty", "()Z", null, javaThread, false); }

} finally

{ instance.enableCollection(); }

}
}
}
} catch (DebugException e)

{ e.printStackTrace(); }

}
return Status.OK_STATUS;
}
};
job.schedule();

return null;
}

private IJavaDebugTarget getFirstJavaDebugTarget() {
for (IDebugTarget debugTarget : DebugPlugin.getDefault().getLaunchManager().getDebugTargets()) {
if (debugTarget instanceof IJavaDebugTarget)

{ return (IJavaDebugTarget) debugTarget; }

}
return null;
}

private IJavaThread getFirstSuspendedJavaThread(IJavaDebugTarget javaDebugTarget) throws DebugException {
for (IThread thread : javaDebugTarget.getThreads()) {
if (thread.isSuspended() && (thread instanceof IJavaThread))

{ return (IJavaThread) thread; }

}
return null;
}
}

Actual results:

Memory consumption of debuggee JVM increases as more classes are loaded in the debuggee JVM.

Expected results:

No memory is leaked by classTrack_addPreparedClass() in classTrack.c.