RFR(S): JDK-8210118: better jdb test diagnostics when getting "Prompt is not received during ... milliseconds" failures

[Gary Adams]

Looks OK to me.
The extra diagnostic output will be useful to have.

On 8/30/18, 11:08 AM, Gary Adams wrote:
> Hi Chris,
>
> It looks good.
>
> Thanks,
> Serguei
>
>
> On 8/29/18 21:19, Chris Plummer wrote:
> >/  Hi,
> />/
> />/  Please review the following:
> />/
> />/  https://bugs.openjdk.java.net/browse/JDK-8210118
> />/  http://cr.openjdk.java.net/~cjplummer/8210118/webrev.00/  <http://cr.openjdk.java.net/%7Ecjplummer/8210118/webrev.00/>
> />/
> />/  There have a been a few jdb bugs (or test bugs) that have caused tests
> />/  to fail because they never get the expected jdb prompt. The only clue
> />/  in the log is an abrupt termination of any jdb output, and the
> />/  following error message:
> />/
> />/  # ERROR: Caught unexpected exception while executing the test:
> />/  nsk.share.Failure: Prompt is not received during 300200 milliseconds.
> />/
> />/  Dumping the pending reply makes it a lot easier to debug most of these
> />/  failures. Here's one example output with the fix in place:
> />/
> />/  Sending command: cont
> />/  receiveReply FAILED due to "nsk.share.Failure: Prompt is not received
> />/  during 300200 milliseconds.".
> />/  Pending reply output follows:
> />/  reply[0]:>
> />/  reply[1]: Breakpoint hit: Arg"thread=main",
> />/  nsk.jdb.locals.locals002.locals002a.allKindsOfLocals(), line=100 bci=62
> />/  reply[2]: umen100           System.out.println("Locals but no
> />/  arguments"); // locals002.BREAKPOINT_LINE2
> />/  reply[3]:
> />/  reply[4]: ts bmain[1] ut no locals
> />/  # ERROR: Caught unexpected exception while executing the test:
> />/  nsk.share.Failure: Prompt is not received during 300200 milliseconds.
> />/
> />/  In this case we can see all sorts of extra characters in various reply
> />/  lines. These characters actually come from a println that was executed
> />/  after execution resumed and before the next breakpoint:
> />/
> />/          System.out.println("Arguments but no locals"); //
> />/  locals002.BREAKPOINT_LINE1
> />/
> />/  Having the pending reply helps a lot here. Without it, you have no
> />/  idea why the main[1] prompt was never seen and might be led to think
> />/  it was never sent. By looking at the pending output you can see that
> />/  main[1] was sent, but it not being detected because of all the extra
> />/  characters appearing on the same line.
> />/
> />/  thanks,
> />/
> />/  Chris
> />

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