[fpc-pascal] When Pascal code is too fast

Marc Santhoff M.Santhoff at t-online.de
Thu Nov 1 00:56:27 CET 2007

Am Donnerstag, den 01.11.2007, 00:45 +0200 schrieb ik:
> Hi List,
> I have a weird problem. the "fpWrite" is too "slow" for FPC code. When
> I have the same exact code in C that writes a big amount of buffers of
> the same size with the same content. It seems that the fpWrite is way
> too fast, and the can't handle another call in the loop, and I need to
> slow down the loop using usleep.
> At the beginning I thought that it was a problem with fpWrite, so I
> created my own binding, but still the problem is the same.
> Except then the fact that it seems that FPC is much faster the GCC,
> any other ideas for such a behavior and what might be the reasons for
> it ?
> A POC for such code btw, can be as follows:
> Pascal:
> ...
> while not EOF(f) do
>   begin
>       readln(f,s);
>       fpwrite(f2, S[0], length(S));
>   end;
> ....
> C:
> ...
> while (! feof(f)) {
>   s_size = fread(f, s, MAX_BUFFER);
>   write(f2, s, s_size);
> }
> ...

What error do you get? Lastly I had something similar with fpc writing
to fast to a non-blocking stderr channel. I haven't had time to do for
my code, but if you get "ressource temporartily unavailable"-like errors
switching the file to blocking mode might help.

Something like

	fcntl(fileno(stderr), F_GETFL) & O_NONBLOCK

or the pascal equivalent should do.


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