William Stein wrote: > On Tue, Aug 30, 2016 at 9:56 AM, Thierry Dumont > <[email protected]> wrote: >> I have two computers, and sage installed on both: >> >> 1) Ubuntu 12.04 , sage-7.3 on an nfs mount,y >> >> 2) Ubuntu 16.04, sage-7.3 on a local system, on a ssd. >> >> With the first one, sage starts slowly (as could be expected!), and I >> have time to look at sage starting with "top". And during the starting >> phase, before the prompt, sage uses more than 16 GB of virtual memory >> (VIRT: 16.380g); the same quantity is used when stopping sage (in the >> console interface). >> It seems quite large, no ? >> >> With the second machine, it's more difficult to see what happens with >> top, but it does not seems to use more than 7gb. >> >> Why such a large amount of memory ? (ok, it's virtual, but it's large, >> no ?).
IMHO horrible (as *each* Sage subprocess is claiming that amount of memory, here usually ~28 to 50+ GB IIRC, as it depends on the physical memory installed) and dangerous, as this makes the usage of 'ulimit -v' nearly impossible and in practice requires to allow vm-overcommit. With the latter, it's presumably quite easy to effectively crash many (if not most) machines, be it by just some bug in Sage, but also by a malicious user of course. (I.e., at least the VM a Sage server / installation may run in.) It also makes it more complicated to see how much memory a Sage process actually *uses*. > I think this is a hack that is used by PARI/GP, due to their > "interesting" primitive (but fast!) memory design. And GAP / libgap. In this recent case I guess the latter is (once again) to blame. I was quite surprised apparently nobody complained, but perhaps not many at all noticed. -leif -- You received this message because you are subscribed to the Google Groups "sage-support" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at https://groups.google.com/group/sage-support. For more options, visit https://groups.google.com/d/optout.
