RFR(S): JDK-8148104 HSDB could not terminate when launched on CLI.

[KUBOTA Yuji]

Hi Dmitry and Jaroslav,

2016-01-25 18:11 GMT+09:00 Jaroslav Bachorik <jaroslav.bachorik at oracle.com>:
> On 23.1.2016 12:13, Dmitry Samersoff wrote:
>> Solution:
>>
>> Create frame before we initialize agent.
>
>
> While this solution will work in this case I think it would be better to
> daemonize the WorkerThread
> (hotspot/src/jdk.hotspot.agent/share/classes/sun/jvm/hotspot/utilities/WorkerThread.java)
> - that should ensure that the application will be allowed to terminate even
> though the worker thread is still running.

It's reasonable for me. I could not come up with the reason why the
WorkerThread is not daemonized, so I wrote simply.
I think that WorkerThread can be abandoned when JVM halts, so
recreated the patch to demonize as below.

jdk9/hs-rt/hotspot (9982:91be2fb6db87)
----
diff --git a/src/jdk.hotspot.agent/share/classes/sun/jvm/hotspot/utilities/WorkerThread.java
b/src/jdk.hotspot.agent/share/classes/sun/jvm/hotspot/utilities/WorkerThread.java
--- a/src/jdk.hotspot.agent/share/classes/sun/jvm/hotspot/utilities/WorkerThread.java
+++ b/src/jdk.hotspot.agent/share/classes/sun/jvm/hotspot/utilities/WorkerThread.java
@@ -35,7 +35,11 @@
   public WorkerThread() {
     mqb = new MessageQueueBackend();
     mq = mqb.getFirstQueue();
-    new Thread(new MainLoop()).start();
+
+    // Enable to terminate this worker during runnning by daemonize.
+    Thread mqthread = new Thread(new MainLoop());
+    mqthread.setDaemon(true);
+    mqthread.start();
   }

   /** Runs the given Runnable in the thread represented by this
----

Sorry, Dmitry, could you please re-upload this patch if you agree with
this idea?

Thanks,
Yuji

> -JB-
>
>>
>> -Dmitry