A very silly question

[Daniel Kegel]

Dimitry Andric wrote:
> I still need to try gcc 3.4.2 on a big C++ app I'm involved with at
> work.  This is because gcc 3.4.0 ICE'd on it, hope it is fixed now...

I had a couple C++ problems with 3.4.0 and 3.4.1, but each problem
was fixed in the next release before I noticed it!

> Actually, for an embedded device I'm working on, we even use glibc
> 2.1.x.  This is because glibc 2.2.x and higher use 2 MB of stack space
> per thread, whereas 2.1.x started with 16 kB, but using mmap() with
> MAP_GROWSDOWN.  Actual commit here:
> http://sources.redhat.com/cgi-bin/cvsweb.cgi/libc/linuxthreads/manager.c.diff?r1=1.54&r2=1.55&cvsroot=glibc&f=h
> 
> So if you don't have swap, as is likely on such a device, you run out
> of memory very quickly, if you want to have a multithreaded
> application...

Or just use ulimit -s to set the default thread stack size smaller,
maybe?  People doing heavy multithreading need to care about that
anyway, even on machines with virtual memory, since you run out
of *address space* at only 500 threads with the default setting.
- Dan


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