Notebook "ulimit -v" does not work

[jdemeyer]

The ulimit -v argument does not do anything at all (I have not tested other ulimit options), neither locally nor remote. Both commands

notebook(ulimit="-v 1")

and

notebook(server_pool=["jdemeyer@localhost"], ulimit="-v 1")

don't seem to put any limit.

[ppurka]

I looked at the code couple of months ago and what it does is baffling. It parses all the parameters and then recombines them and tries to call ulimit. No idea why it does so.

In my opinion, setting ulimit should be an argument to SAGE_ROOT/sage, i.e., SAGE_ROOT/local/bin/sage-sage. Then ulimit should be set by running ulimit <along with the options passed without parsing them> and then Sage or the Sage notebook should be launched. Since Sage or Sage nb will be running in the same shell, it will run with the ulimits that were set.

[jdemeyer]

Replying to ppurka:

Since Sage or Sage nb will be running in the same shell, it will run with the ulimits that were set.

This is not true for remote notebook workers, so we need something more clever.

[leif]

It seems at least your example (-v 1) yields a zero limit, since the value is first divided by 1000.0, then gets converted back to an int, and afterwards gets multiplied by 1000 again.

[ppurka]

Even with all the conversions, I am pretty sure ulimit does not work. That's what brought down our servers on the first day of classes. Everyone had -v set to 2G and yet the Sage process of one person was allowed to run up 20G+ of memory, eating up all the available ram and swap.

[leif]

You may try this (haven't tested the notebook at all):

sagenb/interfaces/expect.py

@@ -47 +47 @@
         if process_limits:
             u = ''
             if process_limits.max_vmem is not None:
-                u += ' -v %s'%(int(process_limits.max_vmem)*1000)
+                u += ' -v %s'%(int(process_limits.max_vmem*1000))
             if process_limits.max_cputime is not None:
                 u += ' -t %s'%(int(process_limits.max_cputime))
             if process_limits.max_processes is not None:

[ppurka]

Oh, also you can check whether ulimit is set by running this from a worksheet:

import os
os.system("ulimit -a")

[leif]

Hahahahaha!!!1!

    def command(self):
        return self._python
        # TODO: The following simply doesn't work -- this is not a valid way to run
        # ulimited.  Also we should check if ulimit is available before even
        # doing this.   
        return '&&'.join([x for x in [self._ulimit, self._python] if x])

(This is WorksheetProcess_ExpectImplementation.command().)

[jdemeyer]

Milestone sage-4.7.3 deleted

[novoselt]

In my experience the only working way to set limits is to edit the sage script to call ulimit if the username is "Sage worker". It is quite annoying to remember to do it between upgrades and in any case this is not what the documentation tells us to do...