RE: 2.4 Official -- memory stuff
Robert Craig wrote:
>
>
> Andy Serpa wrote:
> > No tweak on the memory allocation? I've got a growing list of
> > "un-runnable" programs with 2.4. Is this just a Windows ME problem?
> > You said you had no trouble under XP?
>
> I had no trouble on my 256Mb RAM Windows XP system.
> In fact, your program ran quite fast.
>
> I couldn't see any easy tweak to help you out on ME.
> It was also very slow on my 64Mb ME system
> (even after scaling things down).
> Some things you can do:
>
> - reduce the size of the sequences
> - make more use of integers rather than floating-point
> - create sequences at their final size, rather than
> "growing them" with append or concatenation
>
> In general, 2.4 is faster at allocating memory than 2.3.
> However your program really mangles the system heap.
> On Windows, 2.3 uses Watcom's heap manager, but
> to make Euphoria .dll's work reliably I must use the
> system heap, so that's what 2.4 does. The system heap
> might be using an extra 4 bytes per floating-point number.
> I'm not sure.
>
This has become a more general problem than I thought at first. I had
to break up one of my programs so the "heavy-lifting" is done with a
2.3-translated program instead of 2.4 (other parts make use of the 2.4
features which I don't want to give up -- like user-defined types being
called w/ translator).
For instance, here's a problem: I'm using Diamond, and the 2.3 part of
the program creates a bunch about 150 Diamond entities. (This program
takes 10x longer to run in 2.4 -- that's after rewriting the whole
algorithm. Before it would never finish at all.) Each entity has one
property which will hold a somewhat large sequence (each entity takes
about 1/3 MB on disk after converting to byte code). The goal would be
to hold all these entities in RAM at the same time. I've got plenty
enough RAM to do that. Problem is, even if I create the entities in
2.3, I can't even load them in 2.4 (without it taking forever and a
day)! That's because they're stored on disk as bytecode and after the
bytecode for an entity is read from disk, the entity needs to be
restored with the Diamond function restore_entity(). Apparently this
transformation is enough to "mangle the heap" (unless there really is
just an outright bug somewhere in 2.4) and if I try to load in the rest
of the entities each one takes longer & longer. So now if I want to
have access to all the entities I have to do something like store the
bytecode for each one in an EDS database or something and never have
more than one (or a few, anyway) "restored" at a time. As I said
before, there seems to be a definite threshold for this -- if I load in
one entity everything is fine. And if I destroy that entity before
loading in the next one everything is fine. But if I load in 10 or so
then that's all she wrote. So now I'm in the position where I would
have to restore each entity *EACH* time I want to use it, which of
course causes a different kind of slowdown -- what I really want is
access to all of them at once. There is basically no way around it --
such a program just doesn't work in 2.4 (on this platform) in any
practical sense if I can't even get the objects in memory.
Bottom line: it seems that with ME/98/95, any program which uses more
than a little memory in any sort of flexible way is doomed. Since one
of the main features of Euphoria is supposed to be flexible use of data,
garbage collection, etc., the price seems rather high. I am effectively
limited to programs which use no more than a few MBs of RAM on a machine
which has 512 MB available! I can't be the only one who is going to
have a problem with this...
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