Hi Olivier,
about DeadPlaceException in line 386:
For testing, I modified the lambda in line 274:
() -> {
if (here().id == 1) {
System.exit(42);
}
return new ResilientUTS(wave, group, power, s, r, resilient);
});
In this case, I catch a MultipleException which contains one actual
DeadPlaceException and two suppressed DeadPlaceExceptions. However the
program continues and the result is correct. Without changing
DeadPlaceException to MultipleException the whole program crashes.
I am playing around with these Exceptions in minimal programs and do not
understand the mind of MultipleExceptions. When should a
MultipleException be thrown and when a DeadPlaceException?
Best wishes,
Jonas
Am 09.07.2016 um 15:08 schrieb Olivier Tardieu:
> Hi Jonas,
>
> About DeadPlacesException at line 386. I am not sure.
> What exception other than a DeadPlaceException are you seeing inside the
> MultipleException?
>
> About data loss.
> When I started working with Hazelcast, there was no reliable way to
> detect data loss.
> Hazelcast has added an API for data loss events so it should be possible
> now.
> Have a look at the "Partition Loss Listener" in Hazelcast.
>
> About backup counts.
> Yes this seems reasonable for now.
> Eventually APGAS should expose a configuration parameter for this.
>
> About line 297.
> Yes, the transaction guarantees that we obtain a consistent view of the map.
> In theory, we need this to preclude delayed map updates coming from dead
> places.
> We are working toward preventing such spurious updates and make your
> simpler code correct.
> For now, your code is very unlikely to fail, but there is no consistency
> guarantee.
>
> I have no immediate plan to simplify the resilient map API but I agree
> this would be nice...
>
> Olivier
>
>
>
>
>
> From: Jonas Posner <jonas.pos...@uni-kassel.de>
> To: x10-users@lists.sourceforge.net
> Date: 07/07/2016 08:45 AM
> Subject: [X10-users] [APGAS] Questions about ResilientUTS
> ------------------------------------------------------------------------
>
>
>
> Hi all,
>
> I have a few questions about the ResilientUTS example from the APGAS
> project:
>
> In line 386, the DeadPlacesException has to be a MultipleException,
> right? With DeadPlacesException the program crashes when a places crashes.
>
> When one place crashes after another, the result is false. The reason is
> probably the backupcount of the map. Is there a way to detect data loss?
>
> To tolerate two place crashes, I added the following code before
> initializing the map:
> MapConfig mapConfig = new MapConfig("map"+wave);
> mapConfig.setBackupCount(2);
> hz.getConfig().addMapConfig(mapConfig);
> Is this the preferred way?
>
> In line 297, I don't understand the purpose of:
> final Collection<UTS> values = uts.hz((TransactionalTaskContext
> context) -> { return context.<Integer, UTS> getMap("map" +
> wave).values(); });
> With a simple "final Collection<UTS> values = uts.map.values();" it also
> works in my test cases. What are the advantages of the original?
> As far as I understand, the purpose of executeTransaction in method
> transfer is to guarantee data integrity?
>
> Are there any plans for the future that APGAS provides more
> functionalities to the programmer, so that a APGAS programmer does not
> have to use hazelcast directly?
>
>
> Thanks and cheers
> Jonas
>
>
> ---
> Jonas Posner
> Universitaet Kassel
> Fachbereich 16 Elektrotechnik/Informatik
> Fachgebiet Programmiersprachen/-methodik
> Wilhelmshoeher Allee 71-73
> 34121 Kassel, Germany
>
> Phone: +49 (0)561 804-6498
> Fax: +49 (0)561 804-6219
> mailto: jonas.pos...@uni-kassel.de
> www.uni-kassel.de
>
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--
---
Jonas Posner
Universitaet Kassel
Fachbereich 16 Elektrotechnik/Informatik
Fachgebiet Programmiersprachen/-methodik
Wilhelmshoeher Allee 71-73
34121 Kassel, Germany
Phone: +49 (0)561 804-6498
Fax: +49 (0)561 804-6219
mailto: jonas.pos...@uni-kassel.de
www.uni-kassel.de
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