Re: Seg fault after 2 days of simulation

[Marcus G. Daniels]

>>>>> "JK" == Jan Kreft <address@hidden> writes:

JK> In other words, soon I'll have to
JK> use some sort of supercomputer to run my models, and that will
JK> mean going to pure C rather than Java from Objective C.

This is one reason we developed an extensible language layer rather
than rewriting Swarm in Java.  With or without a parallel version of
Swarm, some users may actually need to look at the assembly code that
GCC generates or even do manual assembly coding to get sufficient
performance for high dimensional spaces of models (e.g. future
versions of BacSim).  They may need to use a massively-optimizing,
highly-tuned proprietary supercomputer FORTRAN compiler and tie those
features in to Swarm.

JK> Preemptively, I have made this years additions to BacSim as close
JK> to C as I could within the limits imposed by the existing
JK> code. 

What I think you mean (not using ObjC messages just for the heck of it,
planned use of memory, using non-OO coding when there won't be
hetergenous agents), is sensible programming anyway.

Do you know in a precise way the distribution of the ways cycles get
spent, i.e. have you profiled BacSim?  Do you know for a fact there
aren't fixable bottlenecks?  Supposing there were a parallel version
of Swarm where all logically concurrent events ran on different
processors, would you still think using low-level code was a solution?

A quick review of swarm-support archives makes it clear that usability
is a bigger problem than performance for most users of Swarm.

However, the fact that Java has resizable strings doesn't imply
inherent slowness.  Strings are just a feature of Java -- you aren't
forced to use it, just as you aren't forced to use objects and
messages in Objective C.  If you want you can make a big array in Java
and dereference into it.


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