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From bill pickup <bill.pic...@yahoo.com.INVALID>
Subject Re: Seasonal djinn blues...
Date Mon, 11 Dec 2017 10:03:26 GMT
 Dear Peter,
Thanks for offering a patch, but that won't be necessary, as I can work around the shutdown
problem by just dumping the JVM through System#exit(..), and the sluggishness problem by just
being patient.
    I checked the shutdown bug on 3.0.1 and it still persists in a modified form, in that
the enigmatic thread, 'Thread-1', is left in LockSupport#parkNanos(..), so in locking. I ran
the Mickey Mouse shutdown test a few times to make sure it wasn't a racy problem.
    To give some context to the source of these slight concerns, I'm trying to build a
replacement for the now tired 'browser' that comes with the distribution. The new stuff uses
JavaFX, so will run on Java 7 and 8, hopefully. I've got as far as event-driven controls for
registrars and group membership, and will look to other functionality of the 'browser' in
fleshing out the candidate. It looks like it's going to be quite a simple application, so
easily modifiable, which can't be said for the 'browser' any more, unfortunately.
Kind regards,
    On Sunday, December 10, 2017, 10:35:21 PM GMT, Peter <jini@zeus.net.au> wrote: 

 Thanks Bill,

I suspect the thread bug was fixed in 3.0.1, are you able to confirm?

I think I can provide a fix for sluggish discovery.

One of the changes with River 3.0 was to remove instances of unsafe 
publication, that is allowing a reference to "this" to escape during 
object construction.

LookupDiscovery was changed to implement Startable (which allows threads 
to start and safe publication to occur after construction), and 
LookupDiscoveryManager was also changed, to ensure safe publication.

LookupDiscoveryManager utilises LookupDiscovery to perform discovery.

I suspect the problem is LookupDiscovery starts before the safe 
publication of LookupDiscoveryManager, so that LDM is not notified 
immediately, becuase LookupDiscovery doesn't have a reference to it yet.

It will be a simple fix to delay starting of LookupDiscovery until after 
LookupDiscoveryManager publication is complete.

Would you like me to provide a patch?



On 11/12/2017 12:53 AM, bill pickup wrote:
>  Hi Peter,
> More from theseasonal djinn…
> So, I had a littlemore patience with River 3.0’s unadorned LookupDiscoveryManager,and
it did indeed recognised the existence of an already running 3.0djinn, but only after a fashion.
River 2.3.3’sLookupDiscoveryManager recognises the same djinn immediately.
> Also noted was atermination concern with 3.0’s LookupDiscoveryManager, which keepthreads
>      sun.misc.Launcher$AppClassLoader@blah_thread-0,and    Thread-1 (?)
> running permanently.
> The former is a bitof a bind, but the latter can be worked around with a system exit
of0, much as must be done in QA.
> Kind regards,
> Bill
>      On Sunday, December 10, 2017, 7:01:49 AM GMT, Peter<jini@zeus.net.au> 
>  Hi Bill,
> Are you trying to discover a lookup service provided by River 2.2.X?
> Which version of discovery are you using?  V2 is now enabled by default
> in 3.0.X, you won't discover any V1 lookup services unless you enable it
> by passing in a ConstrainableLookupLocator using InvocationConstraint
> with DiscoveryProtocolVersion.ONE to LookupDiscoveryManager's constructor.
> If you're still using V1, I'd suggest using LookupLocators to support
> both discovery versions 1 and 2, which should allow you to migrate off
> version 1.
> Version 1 discovery has been deprecated and will likely be removed in a
> future version of River, for now at least, it can still be re-enabled.
> If this isn't the cause, can you enable the loggers for LookupDiscover
> and LookupDiscoveryManager and send us the output?
> Regards,
> Peter.
> On 9/12/2017 11:42 PM, bill pickup wrote:
>> Hi all. Season’s greetings… well, almost.
>> Apologies for coming over the dev@ wire, but the user@ wire seems to be defunct.
Anyway, I’m designing something for River, so I don’t feel too bad.
>> I’m having problems with LookupDiscoveryManager in 3.0.0 and 3.0.1. My call is
>>        new LookupDiscoveryManager(LookupDiscovery.ALL_GROUPS, null, (DiscoveryListener)
>> but this refuses to discover anything. However, it works in 2.2.3, for the same djinn.
>> Is something broken?
>> Kind regards,
>> Bill

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