2-nd round RFR (S) 8032223: nsk/regression/b4663146 gets assert(SafepointSynchronize::is_at_safepoint() || JvmtiEnv::is_thread_fully_suspended(get_thread(), false, &debug_bits)) (original) (raw)

serguei.spitsyn at oracle.com serguei.spitsyn at oracle.com
Tue Feb 4 03:13:20 PST 2014

Please, review the fix for: https://bugs.openjdk.java.net/browse/JDK-8032223

Open webrev: http://cr.openjdk.java.net/~sspitsyn/webrevs/2014/hotspot/8032223-JVMTI-FRAME.1/

Summary:

This is the second round of review for this issue. But it was decided that the JDK-8032223 must be used to cover it instead of the JDK-6471769. The 8032223 was initially closed as a dup of 6471769 but it has been re-open now.

There is a general issue in the suspend equivalent condition mechanism: Two subsequent calls to the JvmtiEnv::is_thread_fully_suspended() may return different results: - 1-st: true - 2-nd: false

This suspend equivalent issue is covered by another bug: https://bugs.openjdk.java.net/browse/JDK-6280037

The bug to fix in this review is a specific manifestation of the 6280037 in the JVMTI GetFrameCount() that has a major impact on the SQE nightly. It is on the Test Stabilization radar as well as the 6280037. There are many tests intermittently failing because of this. I've also decided to fix the same issue in the JVMTI GetFrameLocation() as well.

The JVMTI GetFrameCount() spec tells: "If this function is called for a thread actively executing bytecodes (for example, not the current thread and not suspended), the information returned is transient."

So, it is Ok to call the GetFrameCount() for the non-suspended target thread. To achieve safety, the frame count for non-suspended threads is calculated at a safepoint. It should be Ok and more safe to do the same for suspended threads as well. There should be no big performance impact because it is already on a slow path. It is still important to avoid safepointing when the target thread is current.

The bug 6280037 should go out of the Test Stabilization radar (remove the svc-nightly label) as the most of the impacted tests must be covered by the 8032223.

Testing: In progress: - nsk.jvmti, nsk.jdi, nsk.jdwp - JTreg com/sun/jdi

Thanks, Serguei

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