[10] RFR for JDK-8170299: Debugger does not stop inside the low memory notifications code

[Shafi Ahmad]

Thank you Daniel. I will run and update it with the result.




Regards,


Shafi




On Tue, Sep 5, 2017 at 9:44 PM +0530, "Daniel D. Daugherty" <daniel.daugherty at oracle.com> wrote:











  
    
  
  
    Seems like you should also run: nsk.monitoring.testlist

      

      Dan

      

    

    On 9/4/17 4:11 AM, Shafi Ahmad wrote:

    
    
      
      
      
      
        

Hi,
        

 
        

Please review the fix for ‘JDK-8170299:
          Debugger does not stop inside the low memory notifications
          code’ to jdk10.
        

 
        

With the current implementation ‘debugger
          does not stop inside the low memory *notifications* code’ 
        

This is expected as the notification code
          is getting executed with the service thread, which is a hidden
          thread.
        

 
        

jdk10-dev-new$ jdb -Xmx32m
          MemoryWarningSystem
        

Initializing jdb ...
        

> stop at MemoryWarningSystem$1:25
        

Deferring breakpoint
          MemoryWarningSystem$1:25.
        

It will be set after the class is loaded.
        

> run
        

run MemoryWarningSystem
        

Set uncaught java.lang.Throwable
        

Set deferred uncaught java.lang.Throwable
        

> 
        

. . .
        

> quit
        

 
        

Breakpoint not hit.
        

 
        

With the attached webrev, jdb stop  at
          breakpoint inside notification code.
        

 
        

jdk10-dev-new$ jdb -Xmx64m
          MemoryWarningSystem
        

Initializing jdb ...
        

> stop at MemoryWarningSystem$1:25
        

Deferring breakpoint
          MemoryWarningSystem$1:25.
        

It will be set after the class is loaded.
        

> run
        

run MemoryWarningSystem
        

Set uncaught java.lang.Throwable
        

Set deferred uncaught java.lang.Throwable
        

> 
        

VM Started: Set deferred breakpoint
          MemoryWarningSystem$1:25
        

 
        

Breakpoint hit: "thread=Thread-0",
          MemoryWarningSystem$1.memoryUsageLow(), line=25 bci=0
        

25            System.out.println("Memory
          usage low!!!");
        

 
        

Thread-0[1] step
        

> Memory usage low!!!
        

 
        

Step completed: "thread=Thread-0",
          MemoryWarningSystem$1.memoryUsageLow(), line=26 bci=8
        

26            double percentageUsed =
          ((double) usedMemory) / maxMemory;
        

 
        

Thread-0[1] where
        

  [1] MemoryWarningSystem$1.memoryUsageLow
          (MemoryWarningSystem.java:26)
        

  [2]
          MemoryWarningSystem$2.handleNotification
          (MemoryWarningSystem.java:48)
        

  [3]
          javax.management.NotificationBroadcasterSupport.handleNotification
          (NotificationBroadcasterSupport.java:284)
        

  [4]
          javax.management.NotificationBroadcasterSupport$SendNotifJob.run
          (NotificationBroadcasterSupport.java:361)
        

  [5] java.lang.Thread.run
          (Thread.java:844)
        

Thread-0[1] step
        

> 
        

Step completed: "thread=Thread-0",
          MemoryWarningSystem$1.memoryUsageLow(), line=27 bci=15
        

27           
          System.out.println("percentageUsed = " + percentageUsed);
        

 
        

Thread-0[1] list
        

23        mws.addListener(new
          MemoryWarningSystem.Listener() {
        

24          public void memoryUsageLow(long
          usedMemory, long maxMemory) {
        

25            System.out.println("Memory
          usage low!!!");
        

26            double percentageUsed =
          ((double) usedMemory) / maxMemory;
        

27 =>        
          System.out.println("percentageUsed = " + percentageUsed);
        

28           
          MemoryWarningSystem.setPercentageUsageThreshold(0.8);
        

29          }
        

30        });
        

31    
        

32        Collection<Double> numbers
          = new LinkedList<Double>();
        

Thread-0[1]
        

 
        

In the change, the class ‘MemoryImpl’ is
          derived from class ‘NotificationBroadcasterSupport’ instead of
          class ‘NotificationEmitterSupport’ 
        

NotificationBroadcastSupport takes an
          Executor, MemoryImpl constructor  call super() with an
          executor,  a visible thread.
        

 
        

The method hasListeners() is referenced
           inside MemoryImpl.java and defined in
           NotificationEmitterSupport.
        

This method is not present in
           NotificationBroadcasterSupport so I added it to
          NotificationBroadcasterSupport.
        

 
        

Jdk10 bug: https://bugs.openjdk.java.net/browse/JDK-8170299
        

Webrev link: http://cr.openjdk.java.net/~shshahma/8170299/webrev.01/
        

 
        

Testing: jprt -testset core, vm tonga tests
          nsk.jvmti.testlist, nsk.jdi.testlist, nsk.jdwp.testlist and
          jtreg tests ./jdk/test/com/sun/jdi/
        

 
        

Please let me know if I missed to test some
          more test suit[s].
        

 
        

Thanks to Mandy and Poonam for helping me
          in fixing this. 
        

 
        

Regards,
        

Shafi
      
    
    

  






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