On 11/3/06, Ezra Zygmuntowicz <[EMAIL PROTECTED]> wrote: > > On Nov 3, 2006, at 8:50 AM, Kirk Haines wrote: > > > On 11/2/06, Zed A. Shaw <[EMAIL PROTECTED]> wrote: > > > >> That's probably the best you can do until you can find out why > >> it's leaking. My past > >> experience has been to never trust Ruby's GC or any external C > >> extensions you may be > >> using. I've combed through Mongrel to insane levels to root out > >> all possible leaks I can. > >> Yet, the Sync vs. Mutex bug and recent Array patch from Eric M. > >> shows that Ruby's GC has > >> a long way to go. > > > > I'll 1/2 second Zed's comments here. I've spent a lot of time poking > > around in Ruby internals looking at memory usage. It is very easy for > > someone to write a C extension that mismanages memory and causes Ruby > > to leak, so always look suspiciously at an extension if you have a > > leak that you can't find another cause for, unless you know with great > > confidence that the extension is solid. > > > > The Ruby GC itself is pretty simple and does what it is supposed to. > > It will tend to have performance issues as the set of objects in RAM > > increases, though there are strategies a person can sometimes use to > > manage that, if needed. > > > > The Sync vs Mutex thing, though, can not be laid at the foot of the > > Ruby GC. The problem is with Array.c not releasing it's data in a way > > that allows the Ruby GC to handle it. Refer back to the beginning of > > this email about how easy it is to screw up memory management in C > > extensions.... > > > > Now, that said, if you are using arrays and are using push and shift > > operations to manage an array like a queue (or any libraries, like > > Mutex, that you are using do this), that _will_ bite you in the ass > > with memory usage, because of this Array bug. > > > > Mutex has much better performance than Sync, though, especially if > > there are more than a very small number of threads, so in this > > specific case I continue to use a Mutex, but have patched around the > > problemlematic Array usage by creating my own copy of the Mutex class > > that uses Array in a way that doesn't suffer from the bug. > > > > > > Kirk Haines > > Hey Kirk- > > Would you mind sharing your patched mutex.rb file? I woudl > appreciate it.
IIRC, the patch consist of replacing shift with pop, and push with unshift respectively thus reversing the queue direction. The idea is to avoid Array#shift as it retains the reference to the removed item. _______________________________________________ Mongrel-users mailing list Mongrel-users@rubyforge.org http://rubyforge.org/mailman/listinfo/mongrel-users
