Re: [boost] [mpi] Boost.MPI broken

Subject: Re: [boost] [mpi] Boost.MPI broken
From: Matthias Troyer (troyer_at_[hidden])
Date: 2010-07-02 13:09:47

On 2 Jul 2010, at 07:03, Robert Ramey wrote:

> Thomas Klimpel wrote:
>> Jeremiah Willcock wrote:
>>> It is still broken in the regression tests as of July 1.  Is there
>>> someone
>>> I should email directly to ask about having it fixed?
>> 
>> Looking at the boost users list, I would have guessed that Matthias
>> Troyer is the one that does most of the maintenance for Boost.MPI.
>> However, according to the link Dave send, Doug Gregor is the
>> maintainer. So I took a look at the svn logs, and came to the
>> conclusion that both do some maintenance for Boost.MPI.

Officially Doug has been the maintainer, but he is too busy with clang at the moment so that I took over most maintenance.

>> 
>> I think neither Doug nor Matthias will be enthusiastic when they are
>> requested to find and fix something that somebody else broke,
> 
> I think you're drawing a conclusion here without the requisite understanding
> of the issues.   I think it would likely be better characterised a MPI 
> depending
> on an implementation detail of the serialization library which had to be 
> changed
> to address some other problem.

I disagree. I have taken a first look and it seems that this is caused by a breaking change in the serialization library. Until now an archive was supposed to handle only "primitive" types, which were all fundamental integer and floating point types and std::string. In the new version in addition types like boost::archive::version_type, tracking_type, .... all have to be handled as primitive types by the archive. In the past those types had a serialize function that took care of serialization. 

The list of primitive types that an archive has to support is, in my opinion, not an "implementation detail of the serialization library which had to be changed to address some other problem" but part of the public archive concept.

>> but perhaps it's better than having Boost.MPI broken with nobody fixing it.
> 
> Matthias has agreed  to look at it.

My conclusion from a look at it is above. I'm in touch with Robert and hope that he can again use the serialize() function to serialize those types, as otherwise we'll have to support a larger bunch of primitive types in all archives.

Matthias