Re: binutils, why default stack size this low ?

[Danny Smith <danny_r_smith_2001 at yahoo dot co dot nz>]

 --- Pascal Obry <obry@ACT-Europe.FR> wrote: > 
> > Larger reserves limited the number of threads you could start.  The
> > MSVC compiler had a much smaller reserve than Cygwin before the patch.
> 
> Right, but this has the bad consequence to break some non-threaded
> programs. It was always possible to change the default stack size on the
> command line. 

It still is.

Of course this is also true for non-threaded programs, but
> I
> think that most of the programs around us do not use threads.
> 
> Even on the Ada world, where tasking is part of the language, we have
> many
> programs that do not use tasks (threads), and those who do does not have
> enough tasks to break the limit (which is around 35 if my memory 
> is right).
> 
> Pascal Obry. 

Well, what should the default be? I chose 2 MB because:

1) Default of native compiler is 1 MB. Inspection of apps built by other
W32 comilers indicates they have similar or smaller default stack reserve. 
1 MB, however, is not sufficient to bootstrap GCC. 2 MB is.

2) Threads (and fibers).  Although CreateThread allows user to set stack
size, if size is smaller than default, the new thread uses the same size as
the calling thread.  With fibers, it is not possible to specify stack
reserve; the size of the calling thread is always used. Apps that use
fibers ("lightweight threads") can often (try to) create a 100 or more.


The larger the stack reserve, the more likely that illegitimate 
__stdcall/__cdecl fixups will go undetected.  One way that this can happen
is to compile C code with -mrtd.  Library functions that are not marked as
__cdecl in headers will also be treated as stdcall.  Sooner or later the
stack will overflow. Better sooner than later.

Danny

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