[9] RFR (M): 8050486: compiler/rtm/ tests fail due to monitor deflation at safepoint synchronization

[Filipp Zhinkin]

Hi Vladimir,

thank you for looking at it.

The second thread (which is started in line 75) enters the monitor first.
It is guaranteed by a barrier.

When the barrier passed, the second thread calls wait() on the monitor
and thus inflate and release it.

The first thread then may enter the monitor in line 78.

Thanks,
Filipp.

----- Original Message -----
From: vladimir.kozlov at oracle.com
To: hotspot-compiler-dev at openjdk.java.net
Sent: Monday, December 29, 2014 10:37:16 PM GMT +03:00 Iraq
Subject: Re: [9] RFR (M): 8050486: compiler/rtm/ tests fail due to monitor deflation at safepoint synchronization

Filipp,

I don't understand how you expect progress in lines 78-83 in 
AbortProvoker.java when second thread keeps lock of 'monitor'.
synchronized (monitor) at the line 78 should wait until second thread 
release it so you will never reach line 83.

I would suggest to lunch third thread to inflate monitor and use main 
thread to see the state.

Thanks,
Vladimir

On 12/29/14 8:35 AM, Filipp Zhinkin wrote:
> Hi all,
>
> please review a fix for JDK-8050486.
>
> Following issues cause compiler/rtm/ tests failures
> when safepoint sync happened in the middle of test run:
> - monitors that expected to be inflated are deflated;
> - monitors that expected to be lightweight stack-locks are inflated.
>
> In order to solve the first issue inflation-forcing algorithm
> was modified to wait forever on a monitor that should be inflated.
>
> The second issue is resolved by explicit monitor state checks that
> force deflation in case when monitor is inflated, but it should not.
>
> This fix depends on 8068272:
> http://mail.openjdk.java.net/pipermail/hotspot-compiler-dev/2014-December/016744.html
>
> Bug id: https://bugs.openjdk.java.net/browse/JDK-8050486
> Webrev: http://cr.openjdk.java.net/~fzhinkin/8050486/webrev.00/
> Testing: on host w/ HSW CPU, JPRT, automated on hosts w/ HSW CPU.
>
> Thanks,
> Filipp.
>