[Barrelfish-users] Assertion fired when calling "nameserver_register" function

M Brown M.Brown at huawei.com
Fri Jan 10 18:58:18 CET 2014


Kornilios,
    I guess I'm a bit confused. I'm assuming that when I create a thread it is "not" creating a new domain. If it is that does not make sense. Please clarify the rules and API for thread creation.
Thanks,

Mark Brown
Huawei Technologies Inc.
5340 Legacy Dr., Suite 175
Plano, TX 75024
Tel: 469-277-5700 x5870
Email: m.brown at huawei.com


-----Original Message-----
From: Kornilios Kourtis [mailto:kornilios.kourtis at inf.ethz.ch] 
Sent: Friday, January 10, 2014 10:35 AM
To: M Brown
Cc: Timothy Roscoe; barrelfish-users at lists.inf.ethz.ch; debashis bhattacharya
Subject: Re: [Barrelfish-users] Assertion fired when calling "nameserver_register" function

Hi Mark,

On Thu, Jan 09, 2014 at 05:48:07PM +0000, M Brown wrote:
> Kornilios,
> 
>  I believe that I have found a bug in the nameserver. The problem 
> appears to be in the use of the nameserver functions in multiple 
> threads running on a single core. In this case the nameserver 
> functions are non-reentrant. To illustrate this I took your message 
> example (xmpl-msg) and wrapped both the client and server functions in 
> separate threads and ran the application on a single core. The same 
> assertion fired as illustrated below:
> 
> The nameservice blocking lookup is invoked by the client application 
> near the beginning to get the iref. The server then tries to register 
> the iref in the nameserver and gets the assertion.
> 
> In general for the nameserver to be useful, it needs to be accessible 
> by any number of threads running on any number of cores in a 
> concurrent manner.

It seems that you are using multiple threads (spanned domains) to access the messaging infrastructure of Barrelfish. As far as I know, spanned domains were implemented as a quick way to enable running shared-memory applications, and a significant part of the barrelfish infrastructure (e.g., messages) will not work correctly with them. To the best of my knowledge, the only thing that works reliably on a spanned domain is thread synchronization primitives.

I'm afraid this is not an easy problem to fix. My suggestion would be to avoid spanned domains altogether. If this is not possible the only quick solution I can think of is protecting libbarrelfish invocations with a lock.

cheers,
Kornilios.


>  
> 
> Thanks,
> 
>  
> 
> Mark Brown
> 
> Huawei Technologies Inc.
> 
> 5340 Legacy Dr., Suite 175
> 
> Plano, TX 75024
> 
> Tel: 469-277-5700 x5870
> 
> Email: m.brown at huawei.com
> 
>  
> 
> -----Original Message-----
> From: Kornilios Kourtis [mailto:kornilios.kourtis at inf.ethz.ch]
> Sent: Thursday, December 19, 2013 6:33 AM
> To: M Brown
> Cc: barrelfish-users at lists.inf.ethz.ch
> Subject: Re: [Barrelfish-users] Assertion fired when calling 
> "nameserver_register" function
> 
>  
> 
> Dear Mark,
> 
>  
> 
> On Mon, Dec 16, 2013 at 05:38:37PM +0000, M Brown wrote:
> 
> > Guys,
> 
> >
> 
> >    I’m getting the following assertion fired when calling the
> 
> >    nameserver_register function from within an export callback
> 
> >    function:
> 
> >
> 
> > [cid]
> 
> >
> 
> > The example message test works fine. The structure of the code I 
> > have
> 
> > is as follows:
> 
> >
> 
> > main {
> 
> >                 thread_create(myTask, NULL);
> 
> >                 .
> 
> >                 .
> 
> >                 .
> 
> > }
> 
> >
> 
> > int myTask(void* arg) {
> 
> >                 .
> 
> >                 .
> 
> >                 .
> 
> >                 <iface>_export(NULL,
> 
> >                                export_cb, connect_cb,
> 
> >                                get_default_waitset(),
> 
> >                                IDC_EXPORT_FLAGS_DEFAULT);
> 
> >
> 
> > }
> 
> >
> 
> > void export_cb(void *st, errval_t err, iref_t iref) {
> 
> >                 .
> 
> >                 .
> 
> >                 .
> 
> >                 // The assertion fires within this invocation
> 
> >                 nameserver_register(“iface”, iref); }
> 
> >
> 
> > Is there something I’m doing wrong here?
> 
>  
> 
> [I'm guessing you mean nameservice_register() above]
> 
>  
> 
> Judging from the failed assertion (!_rpc->rpc_in_progress), I'm 
> guessing that it might have something to do with using multiple 
> threads. What are the other threads doing? Can you reproduce the problem when using a single thread?
> 
>  
> 
> cheers,
> 
> Kornilios.
> 
>  
> 
> --
> 
> Kornilios Kourtis
> 
>  
> 
> _______________________________________________
> 
> Barrelfish-users mailing list
> 
> Barrelfish-users at lists.inf.ethz.ch
> 
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> 



--
Kornilios Kourtis


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