hi,

i'm trying to display an L2 modis file. In the band list selection window, i select the loaded band and click display. The display window though that opens up, crashes immediately and I get kicked out of seadas. i also see the following message in my terminal:
GENERIC_FILE_TYPE detected a MODIS file.
grp_name=Geophysical Data
Getting - "sst" data from HDF file...
Segmentation fault

I've turn off randomization according to previous posts, and i get:
kernel.randomize_va_space = 0 when i type: /sbin/sysctl -a | grep randomize

But why is my display still crashing?

I'm using seadas 5.1.5 with the embedded idl license on Fedora core 6 system.

Any ideas?

Hi Yianna, are you sure you have addressed the libXp.so.6 issue as Mark mentioned in this post. It is a bit complex if you are not Unix-savy, but please make sure you understand and resolve the libXp issue, and let us know:

http://oceancolor.gsfc.nasa.gov/forum/oceancolor/topic_show.pl?pid=7929
http://oceancolor.gsfc.nasa.gov/forum/oceancolor/topic_show.pl?pid=7874
http://oceancolor.gsfc.nasa.gov/forum/oceancolor/topic_show.pl?pid=7759
http://oceancolor.gsfc.nasa.gov/forum/oceancolor/topic_show.pl?pid=5962
http://oceancolor.gsfc.nasa.gov/forum/oceancolor/topic_show.pl?pid=8736
http://oceancolor.gsfc.nasa.gov/forum/oceancolor/topic_show.pl?pid=7596
http://oceancolor.gsfc.nasa.gov/forum/oceancolor/topic_show.pl?tid=1919
http://oceancolor.gsfc.nasa.gov/forum/oceancolor/topic_show.pl?pid=7192

Hey Mike,

yes, i had resolved the libXp issue. how complex is the issue?
would it be easier to just buy a new mac computer?

-Yianna

First, try rebooting your system and see if the error goes away.

-How much physical RAM does your system have?

-How much swap space does your system have (you can use the "top" Unix command to see this)?

-Is the Level-2 file you're attempting to load a 5-minute granule?

-Does this segfault occur when you try to load other data files?

-When you load the Level-2 file, try increasing the "Pixel Sample Rate" and "Line Sample Rate".. try setting them to a higher value like "8".

-Also try creating a subscene using Process->MODIS->l2_extract and then try loading this subscene.

Mike,

to answer your questions:

"-How much physical RAM does your system have?"
[yianna@localhost ~]$ free -m
             total       used       free     shared    buffers     cached
Mem:           502        488         13          0          7        263
-/+ buffers/cache:        217        284
Swap:            0          0          0

"-How much swap space does your system have (you can use the "top" Unix command to see this)?"
[yianna@localhost ~]$ top

top - 10:57:53 up 9 min,  1 user,  load average: 0.25, 0.42, 0.29
Tasks: 115 total,   1 running, 114 sleeping,   0 stopped,   0 zombie
Cpu(s):  2.7%us,  0.0%sy,  0.0%ni, 97.3%id,  0.0%wa,  0.0%hi,  0.0%si,  0.0%st
Mem:    514352k total,   507984k used,     6368k free,     6624k buffers
Swap:        0k total,        0k used,        0k free,   304576k cached

  PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND           
2514 root      15   0  171m  14m 6616 S    5  2.9   0:11.41 Xorg              
3215 yianna    15   0 41264  13m 9392 S    1  2.7   0:00.40 gnome-terminal    
3234 yianna    15   0  2164 1008  788 R    0  0.2   0:00.11 top               
    1 root      15   0  2032  640  548 S    0  0.1   0:00.68 init              
    2 root      RT   0     0    0    0 S    0  0.0   0:00.00 migration/0       
    3 root      34  19     0    0    0 S    0  0.0   0:00.00 ksoftirqd/0       
    4 root      RT   0     0    0    0 S    0  0.0   0:00.00 watchdog/0        
    5 root      RT   0     0    0    0 S    0  0.0   0:00.00 migration/1       
    6 root      34  19     0    0    0 S    0  0.0   0:00.00 ksoftirqd/1       
    7 root      RT   0     0    0    0 S    0  0.0   0:00.00 watchdog/1        
    8 root      10  -5     0    0    0 S    0  0.0   0:00.00 events/0          
    9 root      10  -5     0    0    0 S    0  0.0   0:00.00 events/1          
   10 root      15  -5     0    0    0 S    0  0.0   0:00.00 khelper           
   11 root      10  -5     0    0    0 S    0  0.0   0:00.00 kthread           
   15 root      10  -5     0    0    0 S    0  0.0   0:00.00 kblockd/0         
   16 root      18  -5     0    0    0 S    0  0.0   0:00.00 kblockd/1         
   17 root      18  -5     0    0    0 S    0  0.0   0:00.00 kacpid        

"-Is the Level-2 file you're attempting to load a 5-minute granule?"
Yes

"-Does this segfault occur when you try to load other data files?"
Yes. for both L2 and L3 files.

"-When you load the Level-2 file, try increasing the "Pixel Sample Rate" and "Line Sample Rate".. try setting them to a higher value like "8"."
I still get the segmentation fault error.

"-Also try creating a subscene using Process->MODIS->l2_extract and then try loading this subscene."
Still get the error.

Yianna,

It may be that it's crashing because you don't have any swap space set up on your machine.  It's easy enough to set up swap space and there are many references on the web for doing this, here's one:

http://www.cyberciti.biz/faq/linux-add-a-swap-file-howto/

I would suggest adding at least a gigabyte or two.  Let me know how that works out.

Mark

I created 2 swapfiles, 1GB each.
After rebooting my computer, I see the following with the free -m and more /proc/swaps commands
[yianna@localhost used_by_ucy]$  free -m
             total       used       free     shared    buffers     cached
Mem:           502        360        142          0          4        204
-/+ buffers/cache:        151        350
Swap:         2047        117       1930
[yianna@localhost used_by_ucy]$ more /proc/swaps
Filename                                Type            Size    Used    Priority
/var/tmp/swapfile1                      file            1048568 120780  -1
/var/tmp/swapfile2                      file            1048568 0       -2

However, when I try displaying either a L3 or L2 file, I still get the segmentation fault. With the L2 file I still subscene as Mike recommended, and try to display the smaller image, but it display still closes and gives me

Getting - "sst" data from HDF file...
Segmentation fault

Yianna you should find and put old "libX11.so.*" file under the file where you are running seadas and also add a line in your .bashrc.

for bash

export LD_PRELOAD_PATH=/my/private/lib

for tcsh

setenv LD_PRELOAD_PATH /my/private/lib

this my/lib.... has to changed with the path where you put old libX11.so file. For example I am using fedora7 with bash and I put old libX11 file under /home/orek then I add export LD_PRELOAD_PATH=/home/orek line in my .bashrc file.
After modifying .bashrc open new terminal window and run seadas. The trick here is run seadas under the same path, like if you put the libX11 under /home/orek you should run seadas from /home/orek then you may change the working from seadas easily if you like. If you do not have old linX11.so file I can send you via email it is 1 mb file. For editing .bashrc file you may use gedit or other text editors present in Linux..

Cheers

Hasan

ps: you may find some additional info on: http://www.dfanning.com/misc_tips/segfault.html

Yianna,

I suspect that this may still be an issue related to the problems that IDL 6.3 has with libXp.so.6 on FC6.  We have a number of posts concerning this problem on a range of operating system platforms, and it can be very tricky trying to get this to work properly.  I would suggest that if you have been through all of the posts and tried everything and it still segfaults on you, perhaps it's time to consider running something else instead of FC6.  Either that, or purchase a licensed version of IDL 6.4.

Regards, Mark

Hi Mark, Mike, Hasan,

I finally purchased IDL7.0 and the seadas display window works fine now. Thanks a lot for your help.

- Yianna

Ok great to hear Yianna!