[jmm-dev] Actual IRIW use case?

David Holmes david.holmes at oracle.com
Wed Sep 30 07:13:45 UTC 2020

On 30/09/2020 3:11 pm, Martin Buchholz wrote:
> I suspect it's as simple as: the "application" is an IRIW test in jcstress.

No this is code in the monitor subsystem that exposes an IRIW-type 
situation whereby on a non-multi-copy-atomic system we need a full 
fence() rather than a simple loadload() barrier.

Erik Osterlund would have to explain the technical details, but this is 
VM code and nothing to do with JMM or Java-level synchronization.


> VolatileIRIWTest.java:37:@Description("Tests the IRIW sequential consistency.")
> On Tue, Sep 29, 2020 at 1:18 PM Hans Boehm <boehm at acm.org> wrote:
>> I just noticed https://github.com/openjdk/jdk/pull/387 seems to claim that
>> hotspot internally needs to specifically enforce IRIW ordering in places. I
>> haven't had time to explore in detail ...
>> Hans

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