[m-users.] Segmentation fault when executing in parallel

[Volker Wysk]

Hi

I'm trying to parallelize my program, like this:


:- pred parallel(pred(T,U), list(T), list(U)).
:- mode parallel(in(pred(in,out) is det), in, out) is det.

parallel(_, [], []).

parallel(Pred, [T|Ts], [U|Us]) :-
    Pred(T, U)
    &
    parallel(Pred, Ts, Us).


I'm compiling it like this:


mmc -j8 -E --make --parallel \
    -lposix \
    --grade asm_fast.par.gc.stseg.mm \
    mtt


I try to run it with two threads (calling parallel with a list of two
elements, see above). Then I get this runtime error:


*** Mercury runtime: caught segmentation violation ***
cause: unknown
PC at signal: 140069552275084 (7f647be83e8c)
address involved: (nil)
This may have been caused by a stack overflow, due to unbounded recursion.
exiting from signal handler
Segmentation fault (core dumped)


When I use only one thread, then it works fine. When running it with eight
threads, I get this:


Mercury runtime: memory zone pnegstack#36 overflowed

Mercury runtime: memory zone pnegstack#36 overflowed

Mercury runtime: memory zone pnegstack#36 overflowed

Mercury runtime: memory zone pnegstack#36 overflowed

Mercury runtime: memory zone pnegstack#36 overflowed

Mercury runtime: memory zone pnegstack#36 overflowed

Mercury runtime: memory zone pnegstack#36 overflowed

Mercury runtime: memory zone pnegstack#36 overflowed
PC at signal: 139982380928544 (7f5030170e20)
PC at signal: 139982380928544 (7f5030170e20)
PC at signal: 139982380928544 (7f5030170e20)
PC at signal: 139982380928544 (7f5030170e20)
PC at signal: 139982380928544 (7f5030170e20)
PC at signal: 139982380928544 (7f5030170e20)
PC at signal: 139982380928544 (7f5030170e20)
PC at signal: 139982380928544 (7f5030170e20)
This may have been caused by a stack overflow, due to unbounded recursion.
This may have been caused by a stack overflow, due to unbounded recursion.
This may have been caused by a stack overflow, due to unbounded recursion.
This may have been caused by a stack overflow, due to unbounded recursion.
This may have been caused by a stack overflow, due to unbounded recursion.
This may have been caused by a stack overflow, due to unbounded recursion.
This may have been caused by a stack overflow, due to unbounded recursion.


Note that there's no segmentation fault in this case.

What's going wrong? Is this a compiler bug?


Cheers,
Volker
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