I start a new thread in this list as a continuation of "How to limit heavy computations" in sage-support. I try to summarize the problem. In my University, we have two servers to run math labs; it is done in several instances of sagenb using server_pool to enhance (at least a little bit) security. The sagenb instances are launched with ulimit options but it seems they have no effect. In the first term of this academic year, we had several issues affecting the use of this server. Some students started long loops or heavy computations that stop the server (basically their computations blocked one instance and the error messages of the nginx processes grew so much that filled the hard disk). After restarting the machines, the problems came back again; at this point, when we detected such a process it was immediately stopped, but for some reason its instance of sagenb became unusable, causing problems to other students, since it needed restarting (and someone to do it). It was possible (not easy, thanks to Jori Mäntysalo) to identify the actual owner of the process, since stopping the computation by himself caused less harm.
Using ulimit in the OS, namely with the restrictions hard "as 6000000" and "hard cpu 10", it worked. If a computation was too heavy, the process stopped with some error message, but the instance was usable by any other user of the sagenb instance (including the person with the long computation). This was true for Sage 7.3, but no more in Sage 7.4 (and 7.5) where the process was stopped by the instance became unusable in few minutes. Dima Pasechnik proposed to git-bisect and with the help of Miguel Marco, I think I found the patch causing this behavior. I started checking with 7.4 beta and rc and I saw that beta0 had the issue. Looking at the history of changes, it worked after 2b3eb14 Trac #20621: Simpler code and better error messages in Sequence() and it didn't work after 9831d4b Trac #21006: Upgrade to IPython 5.0 Is there any chance to look into this change in order to localize and solve the problem? Regards, Enrique. -- You received this message because you are subscribed to the Google Groups "sage-devel" group. To unsubscribe from this group and stop receiving emails from it, send an email to sage-devel+unsubscr...@googlegroups.com. To post to this group, send email to sage-devel@googlegroups.com. Visit this group at https://groups.google.com/group/sage-devel. For more options, visit https://groups.google.com/d/optout.
