RFR(S): 8246493: JDI stress/serial/mixed002 needs to use WhiteBox.deflateIdleMonitors support

[Chris Plummer]

Hi Dan,

Something is wrong with ProblemList.txt. It doesn't show any changes, 
but I also don't see mixed002 in the file anymore.

Otherwise the changes look good.

thanks,

Chris

On 6/29/20 12:21 PM, Daniel D. Daugherty wrote:
> Greetings,
>
> I have a fix for the following bug:
>
>     JDK-8246493 JDI stress/serial/mixed002 needs to use 
> WhiteBox.deflateIdleMonitors support
>     https://bugs.openjdk.java.net/browse/JDK-8246493
>
> Here's the webrev URL:
>
> http://cr.openjdk.java.net/~dcubed/8246493-webrev/0_for_jdk16/
>
> The test bug that's being fixed:
>
>     vmTestbase/nsk/jdi/stress/serial/mixed002/TestDescription.java fails
>     intermittently with the following message:
>
>      nsk.share.TestBug: There are more than one(2) instance of 
> 'nsk.share.jpda.StateTestThread in debuggee
>
> Summary of the fix:
>
>     Use WhiteBox.deflateIdleMonitors() to make sure that all inflated
>     ObjectMonitors are deflated after each debuggee has been run.
>
> This fix has been tested with a Mach5 Tier5 test run that executes all
> of the JDI tests (along with JDWP, JVM/TI and other Serviceability 
> tests).
> I also did five 100 iteration runs of the failing mix002 test. Each Mach5
> job set ran the test 100 times on Linux-X64, macOSX, and Win-X64 for a
> total of (5 * 100 * 3) iterations of nsk/jdi/stress/serial/mixed002. 
> There
> were no failures.
>
> Thanks, in advance, for any comments, questions or suggestions.
>
> Dan
>
>
> Gory details:
>
> The primary focus of the fix is in the first three files in the webrev:
>
> test/hotspot/jtreg/vmTestbase/nsk/share/jdi/SerialExecutionDebuggee.java
> test/hotspot/jtreg/vmTestbase/nsk/jdi/stress/serial/mixed002/TestDescription.java 
>
> test/hotspot/jtreg/ProblemList.txt
>
> nsk.share.jdi.SerialExecutionDebuggee is the class that used to serially
> execute the debuggee portion of a specific list of tests. After this 
> class
> is done executing a debuggee class, it needs to deflate idle monitors in
> order to prevent a StateTestThread object created by one debuggee class
> from confusing the next debuggee class. Each of the debuggee classes that
> use StateTestThread expect there to be only one of these objects. 
> However,
> since we are running multiple debuggee classes serially *in the same VM*,
> the StateTestThread object created in one debuggee can still be around
> when the next debuggee runs.
>
> The COMMAND_CLEAR_DEBUGGEE implementation clears the currentDebuggee 
> variable
> which permits the debuggee to be GC'ed and is modified by this fix to 
> call
> WhiteBox.deflateIdleMonitors() to make sure that all inflated 
> ObjectMonitors
> are deflated after each debuggee has been run. This takes care of any 
> pinned
> StateTestThread objects (and any other inflated ObjectMonitors).
>
>
> vmTestbase/nsk/jdi/stress/serial/mixed002 is a wrapper style stress 
> test that
> executes the debugger and debuggee parts of a specific list of tests 
> serially
> *in the same VM*. Several of the tests executed by mixed002 make use 
> of the
> StateTestThread class. The failure is intermittent because the order 
> of test
> execution is shuffled automatically and sometimes the ServiceThread 
> manages
> to execute deflation at the right time to prevent more than one 
> StateTestThread
> object from existing at the same time.
>
> The additions to vmTestbase/nsk/jdi/stress/serial/mixed002 are the 
> standard
> boilerplate needed to call WhiteBox functions from test code. The 
> actual call
> to WhiteBox.deflateIdleMonitors() is made in SerialExecutionDebuggee. 
> I did
> attempt a fix where I modified the StateTestThread class to make the 
> call to
> WhiteBox.deflateIdleMonitors() after the internal waitOnObject is no 
> longer
> contended or waited on. That fix reduced the frequency of the failures by
> about half, but it didn't solve the test bug entirely. So I had to 
> make the
> fix in SerialExecutionDebuggee instead.
>
>
> test/hotspot/jtreg/ProblemList.txt is modified to re-enable the mix002 
> test.
>
>
> The remaining nine files are also wrapper style stress tests that execute
> the debugger and debuggee parts of a specific list of tests serially *in
> the same VM*. Because these tests also use SerialExecutionDebuggee, they
> also need the boilerplate changes so that WhiteBox.deflateIdleMonitors()
> can be called.