We at the Harvard-Smithsonian Center for Astrophysics are developing the
next generation of astronomical image display: JS9, a Web-based version of
the de facto standard DS9 (desktop) program. We are using emscripten 1.29.X
to incorporate widely-used astronomical libraries into JS9. See
http://js9.si.edu, which utilizes a standard world coordinate system
library, compiled to JS, to display astronomical positions as the mouse is
moved over the image. Emscripten is a fantastic idea that will make it
possible for our community to transition from desktop to cloud without
having to re-write millions of lines of debugged C code.
We currently are incorporating the de facto standard astronomical I/O
library called cfitsio into JS9 via emscripten. Everything works as
expected to display astronomical images of varying sizes, with one glaring
exception: if a data file is "too large", a request to malloc too much heap
space hangs the browser instead of returning an error. We realize that
there is a limit to the amount of memory that can be allocated, but it
would be preferable to recover gracefully from such a request.
As an extreme example, the test program below will hang both FF and Chrome.
Obviously, we see the hang with smaller requests, depending on how much
heap space has already been allocated.
Any help would be appreciated.
Eric Mandel
#include <stdio.h>
#include <stdlib.h>
// emcc -s TOTAL_MEMORY=67108864 -s ALLOW_MEMORY_GROWTH=1 -o test.html
test.c
int main(){
int bytes=2000000000;
int i, tot=0;
char *buf=NULL;
printf("alloc: %d bytes of memory ... ", bytes);
buf = malloc(bytes);
if( buf ){
printf("got it!\n");
for(i=0; i<bytes; i++){buf[i] = 1;}
for(i=0; i<bytes; i++){tot += buf[i];}
printf("total: %d\n", tot);
} else {
printf("could not allocate memory\n");
}
return 0;
}
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