Re: Still Considering Debian - But Stuck!
Hi,
> Even if I replace the kernel, I'm concerned that there's more involved
> with the more efficient handling of threads from RH 7.3 to RH 9 than
> just a kernel change --
I've installed Debian 3.0r1 with kernel 2.4.18-bf2.4 right from the start
(no need to "replace the kernel") with the required modules for my hardware,
and all partitions are ext3fs. The installation proceedure allows you to
choose kernel 2.4 if you'd like. Also, I have no stability problems with
the 2.4 kernel even though Debian classifies it as an experimental kernel
(i.e., by Debian standards it hasn't reach the maturity it needs to be
considered "stable"). I personally think kernel 2.4 has been around long
enough, and like I said, I have no stability issues with my Debian or SuSE
installations. Though I should admit that my servers do not have quite the
workload yours seem to have.
I would also like to mention that your issue with the Java PIDs I believe to
be more of an issue with the Java SDK/JVM/JRE version you have installed.
I'm not going to pretend to be an expert, but I seem to remember reading
about the new Java version out now, and it's improvements, which includes
much better handling of threads (version 1.4.x). I would be interested to
know which Java version you had/have installed on your RH 7.3 machine(s),
and then on your RH 9 machine(s).?
Lastly, what do you think of the idea of first building one machine with
Debian 3.0r2 with kernel 2.4.18-bf2.4 and Java SDK/JRE 1.4.2_02 and
everything else you need, test for a reasonable amount of time, then convert
the rest.?
regards,
Robert
----- Original Message -----
From: "Fred Whipple" <fwhipple@imagineis.com>
To: <debian-isp@lists.debian.org>
Sent: Monday, February 02, 2004 7:24 PM
Subject: Still Considering Debian - But Stuck!
> Hi Everyone,
>
> A while back I asked for some feedback and got a very rich set of info
> from folks about Debian used in a stable ISP environment as compared to
> other OS's and distributions. All the info was very helpful and helped
> us further solidify our desire (though not yet decision) to make Debian
> our platform as we move forward.
>
> We've run into a couple rather HUGE issues, though, that I'd like to get
> further feedback on. Not that I couldn't figure it all out for myself,
> but nothing beats someone else's experience when it comes to saving me
> the time and heartache ;-) Just about everyone warned me that the
> stable Debian distribution would be old and well tested/maintained, but
> I'm not sure I was prepared for just HOW old...
>
> Our company uses Java --- a LOT of Java. We therefore use a lot of
> threads, and a lot of threads. And a whole mess of threads, too. Under
> Red Hat 7.3, we found that when the system had a total of say, 10,000
> PID's given out (nearly all of them to threads) the system would become
> very unstable. When we moved to Red Hat 9 for the affected systems,
> which includes the new 0(1) scheduler, and either a different kind of
> thread support in either the kernel or GlibC, this problem went away.
> I'm honestly not sure who is responsible for the way threads are
> handled, and I suspect it's not exclusively the kernel, but under RH9
> each JVM (or any app with threads) gets a single PID as normal and all
> very strange behavior that we saw under RH7.3 disappears.
>
> I see that Debian 3.0r2 includes a nicely aged (like fine cheese) Linux
> 2.2 kernel. While I'm certain the aging process only makes its flavour
> stronger and more delectable, I'm afraid it's going to choke at the
> thought of 10,000 threads. Say nothing of 20,000. Now I imagine it's
> not so difficult to simply compile a recent 2.4 (2.5?) kernel and go
> from there. Is this fair? Or would you suppose that the current stable
> Debian is too old in other areas to properly handle kernel 2.4?
>
> Even if I replace the kernel, I'm concerned that there's more involved
> with the more efficient handling of threads from RH 7.3 to RH 9 than
> just a kernel change -- I have to think there was a significant rework
> of some libraries that made threads more efficient under RH9 as well.
> Would anyone be able to identify exactly what that re-working was, and
> conjecture if they think it can be done under 3.0r2? For that matter,
> would I at that point be running so much new technology that I may as
> well be running an unstable distribution of Debian?
>
> Finally, while I'm messing around with the kernel, I'd have to include
> support for ext3fs. In our environment, journaling is not an option,
> it's a base requirement. Of course replacing the kernel would pretty
> much give me kernel-level support for it. From that point, how
> complicated is it to get the rest of the tools to play nicely with
> ext3fs? I'd imagine that a large set of tools would need to be
> replaced, including e2fsck, mount, umount, etc.
>
> Thanks once again for all the info so far!
>
> -Fred Whipple
>
>
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