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Re: [Bug-apl] Segmentation fault causes GNU APL version 1.5-1 AMD64 to e

From: Elias Mårtenson
Subject: Re: [Bug-apl] Segmentation fault causes GNU APL version 1.5-1 AMD64 to exit
Date: Sun, 3 Jan 2016 00:38:10 +0800

Actually the stack size is limited. It's the heap that is not. For C and C++ applications you can set the desired stack size during linking. There is a flag for it but since I'm on mobile right now it's a bit of a hassle to check right now.


On 2 Jan 2016 11:01 p.m., "Juergen Sauermann" <address@hidden> wrote:
Hi Blake,

as of now I suspect the problem is not a too small ⎕WA, but a too
large automatic variable on the stack. General problem in *nix-like OSes
is that they (in practice) never run out of space but begin swapping instead.

And we already have ⎕SYL where you can limit the number of ravel elements available to APL.

You can also set space limits with the ulimit command (a bash built-in).

But none of the above has worked for reproducing the fault.

/// Jürgen

On 01/02/2016 03:36 PM, Blake McBride wrote:
Hi Juergen,

Just a thought, perhaps you can change a parameter in GNU APL (for local testing purposes only) to force a small ⎕wa so that you can simulate the problem and do so more quickly.



On Sat, Jan 2, 2016 at 7:55 AM, Juergen Sauermann <address@hidden> wrote:

I am currently trying to reproduce the fault, but was not yet able to.
Like in Blake's case, 1500x1500 worked on my machine.
I am currently trying 4000x4000 but that hasn't finished yet (takes ages).

The _expression_ that I am using is:


Rick, I suppose you can reproduce the fault more easily. Please try the

1. in the GNU APL src directory, start gdb with GNU APL:

gdb ./apl


2. after the segfault has occurred, print the backtrace (still in gdb):


Thanks a lot,

On 01/02/2016 02:39 PM, Blake McBride wrote:
Just for reference, I tried your example with the head of the source code repository, and I got:

$ apl
      a←1500 1500⍴?(1500×1500)⍴10

However, since your  ⎕wa was substantially less than mine, it may be that you ran out of RAM and I didn't.

Also, what version of the GNU APL source code did you start with?  (The repository head is highly recommended.)

Hope this helps.

Blake McBride

On Fri, Jan 1, 2016 at 2:03 PM, Rick Mayforth <address@hidden> wrote:

The following sequence caused the fault. APL exits. The interpreter is running under Debian 8 in a VMWare virtual machine with 2GB RAM & 880MB swap space. One would expect a WS FULL or some other APL error in this instance rather than a forced exit, no?

a←1500 1500 ⍴ ?(1500×1500)⍴10
Segmentation fault

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