Clint Byrum [2016-01-19 23:52 -0800]: > But that's all nice-to-haves. The real reason I'm still skeptical > is simply that I don't see /tmp usage being a major factor on cloud > instances.
FTR, I agree that it is much more desirable on real-iron (the performance difference with my use cases is *dramatic*, mostly due to fsync() not taking any time on tmpfs). With the (usually) virtualized file systems and memory of cloud instances it should make much less difference. > This sounds great on the surface, however, what real thing does this > benefit? Giant git merges? Sort file usage? If somebody is developing > an app that uses /tmp, they're using /tmp because of these reasons: > > a) They are processing data in an unpredictable way where using RAM > directly may be too costly. Given that /tmp is a tmpfs on a lot of existing machines out there, if your data can become potentially huge you are really better off with using /var/tmp/. > or b) They're using a tool that only operates on files on disk. By far the most common reason that I've seen is that files are the Unix way for exchanging little pieces of data with other programs, like flag files, named pipes, Unix sockets, editors, or in general things you need to call external programs on. I think the latter is what you meant as well with b). But in all but corner cases these are tiny. And in these corner cases it doesn't really matter much whether your program overflows RAM or your root partition -- it's buggy and needs to be fixed, or as a user you just tried to do something unreasonable which your computer is too small to do. So the case where a program dumped 50 GB of logs into /tmp/ -- that's clearly a bug in that program. At that rate it would quickly overflow/DoS any real file system too, apart from the fact that it causes a huge performance drag. I think it's unreasonable to cite this example as a reason why we should not do this. Using /var/tmp/ for big temporary files might work better on some installs (particularly those with small or r/o root and big /var, which is actually fairly common), but I realize it's far from guaranteed to work; but then again, nothing ever is :-) Thanks, Martin -- Martin Pitt | http://www.piware.de Ubuntu Developer (www.ubuntu.com) | Debian Developer (www.debian.org) -- ubuntu-devel mailing list [email protected] Modify settings or unsubscribe at: https://lists.ubuntu.com/mailman/listinfo/ubuntu-devel
