grads-2.0.a1 segmentation fault

[Steven Weiss]

Hi Jennifer,

1. Actually I generate a number of different files and it crashes on different ones at different places, so the time step debug wont help.
2. Not sure what you mean by data type? Its a text or string thats its falling over on when trying to write to file.
3. I'm not familiar with 'limit coredumpsize unlimited'  where/how do I set this?
4. OK, will play with gdb to see what I can get out of it.

Regards
Steven
  ----- Original Message ----- 
  From: Jennifer Adams 
  To: GRADSUSR at LIST.CINECA.IT 
  Sent: Thursday, March 20, 2008 8:47 PM
  Subject: Re: grads-2.0.a1 segmentation fault




  On Mar 20, 2008, at 1:50 PM, Steven Weiss wrote:

    Hi Jennifer,


    Yes, I am looping around the time variable and calling a number of nested
    functions that return a string variable which I print to a file.
    The problem is that its inconsistent so its hard to put the debug code in.
    The script is approx 1000 lines. 
  At the very least you could put something in to say what time step you're at.


    There is no core.
  Use 'limit coredumpsize unlimited' to get core files. On a mac, they get put in /cores 



    I will have to try see if I can catch it.
  Can't really help without more specific info. What data type are you using??


    Is there no possibility that you can run in debug mode e.g. grads --debug?
  What would you have 'grads --debug' do for you? 


  You can try running grads inside the GNU debugger... 
  > gdb grads
  ...
  (gdb) set args -lbc 'myscript.gs'
  (gdb) run


  ... then, when it seg faults, use the 'where' command to find out what caused the crash. 


  Jennifer








    Regards
    Steven




    ----- Original Message -----
    From: "Jennifer Adams" <jma at COLA.IGES.ORG>
    To: <GRADSUSR at LIST.CINECA.IT>
    Sent: Thursday, March 20, 2008 6:28 PM
    Subject: Re: grads-2.0.a1 segmentation fault




      On Mar 20, 2008, at 8:10 AM, Steven Weiss wrote:


        Hi,


        I'm running grads 2.0.a1 on Suse Linux and every so often I get a
        segmentation fault. Its very inconsistent. The only thing I can see
        is that
        it is always during writing out a file. i.e. rc= write (filename,
        variable).
        From looking at the file, the variable data is normally only half
        written
        and the problem is not always in the same place.


        How can I go about identifying what the problem is?
      Well ...
      I can't fix I bug I can't reproduce, so you have to find a way to get
      GrADS to seg fault reliably. Try putting some debugging statements in
      your script so you'll know where it's dying, e.g. if it happens
      during a loop. There are some known problems in 2.0.a1 that have
      already been addressed ... what data type are you using?


      If you've got a core file, you can try using gdb (gnu debugger) to
      see where it died:
      > gdb grads
      ...
      (gdb) core your.core.filename


      Then gdb will say where in the GrADS code it was when it seg faulted.


      Jennifer


  --
  Jennifer M. Adams
  IGES/COLA
  4041 Powder Mill Road, Suite 302
  Calverton, MD 20705
  jma at cola.iges.org





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