On Sun, Sep 03, 2006 at 02:41:32PM -0500, Neil Gunton wrote: > Hi all, > > I am using Sarge on AMD64 (dual Opteron). I noticed recently that there > were some issues with the stock version of Perl - "v5.8.4 built for > x86_64-linux-thread-multi". Messages were appearing in my apache error > log every time a child process terminated, to the effect that "2 or more > threads are running". I wasn't starting multiple threads, so this always > mystified me. At the same time, I was noticing that at times of higher > webserver load, the CPU "system" load and fork rates were spiking > unreasonably (going to over 120 forks per second). I had a suspicion > about the multithreaded perl, as I had never seen this before on my > previous servers, which had the same software setup (2.6 kernel, apache > 1.3.x), except that they had had non-multi-threaded Perl installed. > I don't know much about Perl, but I will try to help.
> I am no expert on debian packages, and I couldn't find any references on > the Web for either getting pre-built non-threaded Perl, or how to build > a debian package for it. The process for getting Perl 5.8.8 from > unstable or testing scared me, because it seemed that the package had > dependencies that would mean a whole lot of other stuff might need to > also be upgraded. Also, I assume that the newer versions would also be > multithreaded, which wouldn't help all that much if threading is the > problem. I don't really fancy upgrading a lot of core packages to > testing or unstable on my production server, which is unfortunately the > only AMD64 (or debian for that matter) box I have access to. My > workstation is slackware. > The two most critical packages (or sets of packages) in a Debian system are libc6 and Perl. If you mess with those, it can be close to impossible to get your system back into a consistent state. > So I decided to try building my own non-threaded Perl, from source. I > got the source for 5.8.8 from perl.org, and it built ok as non-threaded, > and I was able to get apache with mod_perl built using it. I also had to > re-build all my perl modules, but that was ok. The thread error messages > disappeared from the apache logs, and munin now shows that the CPU > spikes have all but disappeared (you can still see a rise in CPU usage > and forkrate when the web traffic increases, but it is nothing like the > spikes we had before). So I guess this helped fix the problem, for > whatever reason. > > However I quickly discovered that by replacing the Debian Perl with my > own, it broke a bunch of stuff, such as apt-get. I got all kinds of > errors because things like deb-conf appeared to now be broken with the > new perl. I couldn't find out easily what was missing - no reference to > deb-conf or the other stuff that was missing on CPAN, and Debian itself > seemed to be very confused because it thought its Perl should be there, > but it wasn't. > > I tried removing the Debian version of Perl, to make it cleaner so that > the new one was the only version lying around, but quickly discovered > that dozens of other packages depend on it - I would end up also > removing all manner of essential utilities. So I obviously have to leave > the Debian Perl in place. > > I ended up building apache with my new perl, but then afterward > re-instated the /usr/bin/perl with the old version. This appeared to > make everything work again with apt-get, but my apache is still using > the newer version. I don't like this, it seems very kludgy and rickety - > when I need to build apache again, I'll have to remember to temporarily > re-instate my new version during the build. > > Obviously there are issues with building your own perl, but I'm sure it > must be possible to do it using the "official Debian way". Can anyone > give me a step-by-step instructions on how you're supposed to build your > own Perl on a Debian system, while still keeping everything happy? > If you want to customize your Perl packages, then check out my HOWTO on building custom Debian packages: http://familiasanchez.net/~roberto/howtos/debcustomize Of course, be careful. :-) > Thanks! > > /Neil > Regards, -Roberto -- Roberto C. Sanchez http://familiasanchez.net/~roberto
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