Re: [xml] xmlDocDumpMemory() is VERY slow on Win32

[<Eric Zurcher csiro au>]

Hi.

Steve's simple little sample program gives some very interesting results on my Windows 2000 system. Using VC 
7, I get an executable that takes about 19 seconds to run. When I compile with gcc, the resulting executable 
runs in under a second. If I use the Borland compiler to build a command-line application, it also requires 
about 19 seconds to run, but if I use the same compiler, but build it as a VCL (Windows) application, it runs 
in under 1 second! No such change in performance was obtained, however, when using VC 6 to build a Windows 
application.

These differences are apparently due to differences in the way the various run-time libraries are handling 
"realloc". 

Well, Steve, maybe you can just switch compilers and RTLs instead of switching platforms <G>.

Eric Zurcher
CSIRO Livestock Industries
Canberra, Australia
Eric Zurcher csiro au

> -----Original Message-----
> I now share Igor's bad feeling about this in the light of the following 
> program:
>
> #include <stdio.h>
> #include <stdlib.h>
> #include <malloc.h>
> #include <time.h>
> void main(void) {
>   char *buf;
>   int i, size;
>   time_t start, end;
>   size = 16000;
>   if ((buf = malloc(size)) == NULL) {
>     printf("malloc failed\n");
>     exit(3);
>   }
>   else {
>     printf("malloc OK (%d)\n", size);
>   }
>   time(&start);
>   for (i = 0; i < 640; i++, size += 16000) {
>     if ((buf = (char *)realloc(buf, size + 16000)) == NULL) {
>       printf("%03d: realloc failed\n", i);
>       exit(4);
>     }
>     else {
>       printf("%03d: realloc OK (%d to %d)\n", i, size, size + 16000);
>     }
>   }
>   time(&end);
>   free(buf);
>   printf("%d seconds\n", end - start);
>   exit(0);
> }
>
> Could somebody please try this on Linux (well, anything other than Win32 
> I guess) and tell me how long it takes to run?
>
> On my P4 2GHz Win32 box it takes 15seconds -- exactly the same time as 
> the XML parsing/dumping earlier!  (And it's just as slow without the 
> printf() calls in it.)
>
> I dare say the time will be 0 or 1 second on Linux.
>
> My soul is indeed lost :(  Where do I go from here?  (Don't say Linux...)
>
> - Steve