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

[Juergen Sauermann]

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.

Thanks.

Blake

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

Hi,

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:

 ⌹?(Q,Q←4000)⍴10

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

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

gdb ./apl
run
⌹?(Q,Q←1500)⍴10

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

bt

Thanks a lot,
Jürgen

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

      ⎕wa

732487680

      b←⌹a

      )off

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

      ⎕wa

193433600

      b←⌹a

Segmentation fault