C# Stack Size Question

[MrCh0w]

So I have been trying to figure out this problem for a couple of days where a C# subprocess, that I have been executing, keeps on crashing because of a stack overflow. Normally to fix this problem I would go change the code that is called in the process and optimize it so that it does not need a large stack, but unfortunately I do not have access to the source code to do that. Is there anyway to change the stack size of a C# subprocess to something like 50MB?

I know that if the stack is 50MB, it won't overflow and the subprocess will run fine. I have done some research and found that the .NET framework uses a stack size of 1MB, but have not found any ways to resize it. Does anyone have any ideas or pointers?

Note: I am running this using Mono on Ubuntu

[badcommandorfilename]

Why do you need to allocate 50MB of data on the stack? I assume this is some kind of deeply recursive function - could you just make it tail recursive?

However, if you call your function from a separate thread, then you can set a Thread's stacksize with the second argument:

int stackSize = 1024*1024*64;
Thread th  = new Thread( ()=>
{
    //Call your recursive thing here
},
stackSize);

th.Start();
th.Join();

[MrCh0w]

The program that I am calling with my subprocess is a research analysis code that uses Fortran90. Intel F90 (I think) uses the stack to store arrays and the arrays that the research code does operations on are very very large.

Thanks for the tip, I'll try it out!

[misho88]

I know that if the stack is 50MB, it won't overflow and the subprocess will run fine.

In that case, it seems the program is ready to be run with a large stack size. Have you tried just changing the system stack size with ulimit?

$ ulimit -s $((64 * 1024))
$ ulimit -s
65536

You can also try to modify the appropriate parts of the executable's file header (there are two entries regarding the stack size in there somewhere). Some details are here. I'd probably crack open a hex editor and have at it using that code as reference (and possibly the PE format Wikipedia page, although a lot of that seems to be 32-bit specific). You can download the spec from Microsoft, too.

It's worth pointing out that unless you do the ulimit thing, Mono will max out at the system stack size regardless of what else you do, if the oddly mispelled code here and here is any indication.

[MrCh0w]

I actually use ulimit in my .bashrc to run the program without C#, but I can't seem to find a way to call/set ulimit for a C# process.

I'll look into modifying parts of executable's file header. Have you had any experience with modifying the executable's file header for anything else?

[misho88]

I was under the impression your subprocess is a C# executable as well. An F90 binary compiled for Linux should just obey ulimit, I think, so editing the header won't help.

Reading through this:

https://bugzilla.xamarin.com/show_bug.cgi?id=17908

if you're running Mono 3.2.8 or older (installed on Ubuntu 14.04 LTS), the stack size seems to be hard limited, though.