Re: Parallel Question and Swarm Future

[donalson]

Cool Marcus!

Thx,

   D3

Marcus G. Daniels wrote:

> D3> As I understand parallelization (sp? Or even word?) as it pertains to a
> D3> Swarm type simulation, is distributed computing.
>
> There are five potential sources for parallelism in Swarm:
>
> 1. Multiple actions scheduled for the same absolute time step at a
>    toplevel Swarm merge schedule.  This is fairly common.
>
> 2. ActionGroups that are created by hand.
>
> 3. Intra-process unsynchronized Swarms.
>
> 4. Inter-process unsynchronized Swarms simulations communicating by IPC.
>
> 5. Partial order constraints (not yet implemented).
>
> The most fundamental kinds of parallelism that we want to support are
> #1 and #2.  We haven't decided on a particular approach, although
> POSIX threads and MPI + object migration are two possibilities.
>
> #3 and #5 are nice add-on capabilities once the low-level support
> exists.  Resourceful users can do #4 now, but when we finish work on
> distributed multilanguage support (starting in January), it will be
> easier.
>
> D3> Given that, the collections library needs an overhaul.  This is a
> D3> significant problem as all of the scheduling code is based on
> D3> collections.  It schedule routines are also very complex and rather
> D3> fragile.  It seems to me that if Swarm is going to continue, this is the
> D3> next big step.
>
> There isn't anything really wrong with collections library at the
> design level, and the current implementation isn't hurting the
> performance of current scheduling feature set.
>
> So although we don't plan an rewrite of the collections library for
> the sake of scheduling, we will be adding support for ordered (AVL or
> red/black trees) and unordered (hash table) versions of Map and
> sibling protocols.  This won't be in the next relase, though.
>
> Rest assured, the collections and activity libraries are receiving
> attention, and will continue to do so.
>
> Incidentally, Vladimir has already completed The Dynamic Scheduling
> Bug Fix.  The other features to be in 1.4 are object serialization,
> HDF5 support for reading and writing large and complex datasets, and
> randomized indices (primarily for shuffling ActionGroup execution
> order).  Swarm 1.4 will be available early January.
>
> D3> Is it too much to think about a translation to C++?
>
> >From January to March we will be implementing multilanguage support
> with a special emphasis on Java.  *If* C++ is supported, it will only
> be because we get it as a side effect of a larger effort.
>
> We are following the work Cygnus is doing with their GCC-based Java
> bytecode compiler, and may help enhance their new runtime and/or the
> Objective C runtimes to work together.  Since Cygnus also maintainer
> the GNU C++ compiler, there *may* be some effort made to facilitate
> interoperability between Java and C++ within GCC.
>
> Alternatively, Swarm support for C++ might come if we decided to add
> Objective C support to a popular CORBA implementation like ILU.  This
> is not to imply that CORBA is a substitute for multilanguage support
> by the compiler.  Generating CORBA's IDL is easy, and may prove useful
> for other system integration reasons, however it probably would be
> slow on the first cut as well.
>
> The only constraints we have placed on ourselves so far are to support
> Swarm models written in Java, and create and use infrastructure that
> generalize to other languages.
>
> The ETA for Swarm 2.0 is mid-March.  After multilanguage is done, the
> universe of options for parallelism (and potential contributors) will
> be larger.
>
>                   ==================================
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                  ==================================
   Swarm-Modelling is for discussion of Simulation and Modelling techniques
   esp. using Swarm.  For list administration needs (esp. [un]subscribing),
   please send a message to <address@hidden> with "help" in the
   body of the message.
                  ==================================