[Issue 5176] Limit static object sizes

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http://d.puremagic.com/issues/show_bug.cgi?id=5176



--- Comment #15 from bearophile_hugs at eml.cc 2013-01-09 18:30:05 PST ---
(In reply to comment #13)
> Very large structs can also corrupt memory not just via null references, but
> via stack overflow. (Just pass a large struct by value down a few levels of
> recursion, and the stack will overflow.) And it's easier than one might think:
> 
> struct S {
>   dchar[256] buffer;
> }
> 
> Looks small, right? Well, sizeof(dchar)=4, which means sizeof(S)=1024. On
> Linux, the default stacksize is about 4KB. That means passing S by value down
> just 3-4 levels of recursion is enough to overflow the stack.

A 1 kb struct should be considered very little for the stack. Generally it's a
good idea to use the stack in D, because it avoids many slow heap allocations
and decreases pressure on the GC.

On a modern PC with 1 GB RAM a D programmer should be free to use 1-10 MB of
RAM for the stack. On Windows there is a linker command to increase the stack
size.


> And currently, I
> don't think DMD does any handling for stack overflow; it just crashes (and may
> corrupt memory as well, I didn't look into it).

DMD used to give a readable error message on Windows, but now programs just
crash.

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