RFR 8217347 [TESTBUG] runtime/appcds/jvmti/InstrumentationTest.java timed out

[Ioi Lam]

On 3/24/19 9:14 PM, David Holmes wrote:
> Hi Ioi,
>
> On 25/03/2019 1:46 pm, Ioi Lam wrote:
>> https://bugs.openjdk.java.net/browse/JDK-8217347
>> http://cr.openjdk.java.net/~iklam/jdk13/8217347-appcds-InstrumentationTest-timeout.v01/ 
>>
>>
>> This test case used VirtualMachine.list() to find the pid of the the 
>> child
>> process. However, as David Holmes commented in the bug report, it's
>> suspected that this call may lead to timeout.
>>
>> In any case, since Process.pid() has been added since JDK 9, it's 
>> better to call this
>> API directly. That way, we can avoid unnecessary dependency on 
>> VirtualMachine.list().
>
> In so far as I can see how you replaced the VM.list() with 
> Process.pid() this seems okay. I'm having trouble actually 
> understanding the handshake being used to control things though. I 
> would have expected the target VM to create the flagfile to indicate 
> it is ready for attaching, then it would wait for the flagfile to be 
> deleted.
>

Hi David,

As far as I can tell, the handshake is this: the main test process 
creates the flag file and passes the name of the flag file to the child 
process (whose main class is InstrumentationApp). The child process will 
wait until the main process deletes the flag file.

After the child process is launched, the main process attaches to it 
(using the child's pid), and then deletes the flag file. At that point, 
the child will resume execution.

BTW, I found this comment to be out-dated so I changed it:

-        // At this point, the child process is not yet launched. Note that
-        // TestCommon.exec() and OutputAnalyzer.OutputAnalyzer() both block
-        // until the child process has finished.
-        //
-        // So, we will launch a AgentAttachThread which will poll the 
system
-        // until the child process is launched, and then do the attachment.
-        // The child process is uniquely identified by having flagFile 
in its
-        // command-line -- see AgentAttachThread.getPid().

+        // At this point, the child process is not yet launched.
+        // We will launch a AgentAttachThread which will wait until
+        // the child process's pid is known, and then do the attachment.
          AgentAttachThread t = new AgentAttachThread(flagFile, agentJar);
          t.start();
          return t;

Thanks
- Ioi

> Thanks,
> David
>
>> Tested with tiers{1,2,3}. Also removed some unnecessary @module and 
>> import lines.
>>
>> Thanks
>> - Ioi