RFR: 8170299: Debugger does not stop inside the low memory notifications code

[serguei.spitsyn at oracle.com]

Hi Daniil,

I've not finished my review but it looks good in general.

A couple of quick comments.


https://cr.openjdk.java.net/~dtitov/8170299/webrev.01/src/hotspot/share/runtime/notificationThread.hpp.html

  I wonder if this function is also needed:
    static bool is_notification_thread(Thread* thread);


https://cr.openjdk.java.net/~dtitov/8170299/webrev.01/src/hotspot/share/runtime/notificationThread.cpp.html

I wonder why this include statement is missed:
   #include "runtime/mutexLocker.hpp"

Also, these have to be correctly ordred:

   29 #include "runtime/notificationThread.hpp"
   30 #include "services/lowMemoryDetector.hpp"
   31 #include "services/gcNotifier.hpp"
   32 #include "services/diagnosticArgument.hpp"
   33 #include "services/diagnosticFramework.hpp"


Thanks,
Serguei


On 7/3/19 8:04 PM, Daniil Titov wrote:
> Please review the change the fixes the problem with the debugger not stopping in the low memory notification code.
>
> The problem here is that the ServiceThread that calls these MXBean listeners is hidden from the external view that prevents the debugger from stopping in it.
>
> The fix introduces new NotificationThread that is visible to the external view and offloads the ServiceThread from sending low memory and other notifications that could result in Java calls ( GC and diagnostic commands notifications) by moving these activities in this new NotificationThread.
>
> Testing: Mach5 tier1,tier2 and tier3 tests succeeded.
>
> Webrev: https://cr.openjdk.java.net/~dtitov/8170299/webrev.01/
> Bug: https://bugs.openjdk.java.net/browse/JDK-8170299
>
> Thanks!
> --Daniil
>
>