How to track locking events in JVMTI

Question

JVMTI offers the events ContendedMonitorEnter and ContendedMonitorEntered to detect events related to the use of synchronized. synchronized is nothing else, but a ReentrantLock.

Now I would like to track also events related to the lock structure: ReentrantLock. I could hook to method entry/exit of its lock() and unlock() events. However, these event hooks don't provide any information about the object they were invoked on. Thus I cannot distinguish between different ReentrantLock and thus cannot log any information about which lock is currently locked.

Is there any other way to keep track of this?

score 0 · Accepted Answer · answered Sep 08 '11 at 19:51

0

You'll have to instrument the classes being loaded by yourself. This is rather complicated, but fortunately we have java_crw_demo.c which is supplied (alongside with other helpful examples) together with JDK. There you can find an implementation that does some basic kinds of instrumentation. You can easily modify it to do the job. I am doing this now for some academic student project.

answered Sep 08 '11 at 19:51

dkrikun

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But for more interesting instrumentation it seems to be more useful using instrumentation libraries like ASM, isn'it? – Konrad Reiche Sep 08 '11 at 20:17
ASM will make instrumentation much easier. – dkrikun Sep 13 '11 at 18:55
So this would basically force you to use Java agents anyway, isn't it? – Konrad Reiche Sep 13 '11 at 20:13
No, it would not. I wanted to say that ASM is probably much better suited for static instrumentation than JVMTI, because it is easier to work with. – dkrikun Sep 14 '11 at 18:26
Yes, but ASM is used through a java agent, isn't it? – Konrad Reiche Sep 14 '11 at 18:37
Dont't know for sure, anyway, it does not force you to use JVMTI/JNI. – dkrikun Sep 15 '11 at 16:05

How to track locking events in JVMTI

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