Re: [Caml-list] segmentation fault

["Markus Weißmann" <markus.weissmann@in.tum.de>]

On 2017-06-19 23:15, Josh Berdine wrote:
> On Mon, Jun 19 2017, Julia Lawall wrote:
> 
>> On Mon, 19 Jun 2017, David MENTRÉ wrote:
>> 
>>> Hello Julia,
>>> 
>>> Le 2017-06-18 à 21:41, Julia Lawall a écrit :
>>> > Over several
>>> > runs on two different laptops, the backtraces have nothing obvious in
>>> > common.  The bytecode version does not seem to stack overflow.  Adding
>>> > Gc.print_stat() at a periodic quiescent point in the execution did not
>>> > show a memory leak.
>>> 
>>> A similar issue related to random crash in native code version was 
>>> asked
>>> by Alexey Egorov on this list 9 days ago. Daniel Bünzli advised to 
>>> him
>>> to frequently call Gc.full_major () to have a crash closer to the 
>>> real
>>> issue.
>> 
>> OK, I will try this.
> 
> Are you using Windows? I have only experienced segfaults from stack
> overflow on Windows.
> 

you can easily get a stack overflow on Linux when you use C bindings:
the "stack touch" that checks for sufficient free space on the stack
before calling external code may well trigger a SEGFAULT, even though it 
is
not the fault of the C-code but of the OCaml-code that filled the stack.

I found my bug by adding [@tailcall] annotations to the recursive 
function
calls I initially assumed would be tail recursive.

regards
Markus

-- 
Markus Weißmann, M.Sc.
Technische Universität München
Institut für Informatik
Boltzmannstr. 3
D-85748 Garching
Germany
http://wwwknoll.in.tum.de/