Re: Malloc can not allocate memory

[Wolfram Gloger]

> Just out of curiosity, could I ask where I can read (web page?) about
> /proc/../maps file.

google.com with "linux memory map /proc" gets me a reasonable first
hit.

> I
> use glibc version 2.1.3-24, which, perhaps may have the problem of "mmap
> versus sbrk". (I am not knowledgeable enough to see the problem.)

In any case, that is ancient software. glibc-2.2.4 was released about
1.5 years ago, and is the absolute minimum version I would recommend.
Nevertheless, I remember introducing mmapped arenas when sbrk ran out
even in glibc-2.1.x times.

> But
> would not the same problem show up in both cases? Why would Monte Carlo
> one, which takes about 15 KB out of 2 GB less run and the "real" terminate
> at 780 MB?

The allocation pattern is obviously different.  You can fragment the
heap even with just very small chunks.  Once you have allocated just a
few 15kB chunks with bigger chunks in between, you can not expect to
get the whole address space back even when you have freed all the
bigger chunks.

> Is it possible to use newer library, despite the fact that
> systems administrator does not want to update it?

Yes this is possible.  You can install ld.so.2 and libc.so.6 in your
private directory and execute commands like:

/yourpath/ld-linux.so.2 --library-path /yourpath command [args]

You could also try -- and this is perhaps the easiest alternative --
to just link your application statically (use gcc -static).  Perhaps
the problem then goes away even with your ancient glibc!

>  I understand that 2.1.3 and 2.2.5 should have the save
> interface (*.h files). Do they?

No.  You should get the header files as well.

> If I follow this path,... Should there be
> a match between the version of the standard library and the kernel
> version?

No, this isn't required, the kernel should have zero to do with all
this.

Regards,
Wolfram.