[sage-support] Re: permission denied for .png files in /tmp when using server pool

[Volker Braun]

Should be fixed in 6.5.rc3


On Monday, February 16, 2015 at 5:55:40 PM UTC+1, Kyle VonBlohn wrote:
>
> Hi,
>
> My apologies if this has been answered elsewhere, as I have searched, but 
> have not found anything related to this specific problem.
>
> I have a sage server (6.4.1) running on Ubuntu 14.04 amd64.  I used 
> instructions found here: http://wiki.sagemath.org/SageServer by Jason 
> Grout, and here: https://help.ubuntu.com/community/SAGE on the ubuntu 
> wiki.  I have everything setup as specified, i.e. rsa keys so that user 
> sageserver can ssh into sage*@localhost without a password, and have 
> created a directory /sagenb with ownership sageserver:sageuser (where 
> sageuser is the group to which the server_pool accounts and sageserver 
> belong) and permissions of 775.
>
> What I am experiencing is that when using the server pool, calculations in 
> the notebook work as expected, i.e. 2+2 returns 4 when shift-enter is 
> pressed.  However, any commands where a png is created and returned, such 
> as plot(cos,(-5,5)), evaluate but are not displayed.  when I check the 
> server console, I am seeing the following:
>
> 2015-02-16 11:32:36-0500 [HTTPChannel,7,<ipaddress>] Error copying file 
> from worksheet process: [Errno 13] Permission denied: 
> '/tmp/tmp4juuwE/sage0.png'
>
> looking further, i see this:
>
> root@Sage:/home/ladmin# ls -la /tmp/tmp4juuwE/
> total 44
> drwxrwxrwx 2 sageserver sageserver  4096 Feb 16 11:32 .
> drwxrwxrwt 7 root       root        4096 Feb 16 11:33 ..
> -rw-r--r-- 1 sage3      sageuser     132 Feb 16 11:32 ___code___.py
> lrwxrwxrwx 1 sageserver sageserver    43 Feb 16 11:32 data -> 
> /sagenb/nbfiles.sagenb/home/kvonbloh/0/data
> -rw------- 2 sage3      sageuser   26589 Feb 16 11:32 sage0.png
> -rw-rw-r-- 1 sageserver sageserver   370 Feb 16 11:32 _sage_input_2.py
> root@Sage:/home/ladmin#
>
> it appears the .png file created by the "worker" process has permissions 
> of 600.  so when sageserver attempts to copy it from the tmp directory back 
> into the worksheet, it cannot read the file.  If I remove the server_pool 
> line from my startnotebook script and it runs with only the single account, 
> everything works fine and images are displayed in the worksheet as expected.
>
> Any idea what I may be missing?  we would like to implement sage for our 
> mathematics courses here at the university, but i suspect when we have 60+ 
> users working on it simultaneously, running it with the single user process 
> will severely impact performance.  I am new to sage, so any help would be 
> appreciated.
>
> Thanks,
> Kyle
>

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