JVM GC Algorithms

Not really much unique content today... but if you're a java person here are a couple very helpful links. I've often tried to figure out exactly which gc algorithms are being used, how that corresponds to which jvm params you use, and if certain young/tenured garbage collectors have to be used together. I've known for a long time that jconsole will show you which ones are being used, but the names it uses don't always seems to correlate to other documentation, jvm params, etc.

So I got on this hunt the other day of figuring out the specifics and found these two resources which in my mind, spell out all the details!

A Sun engineer's blog post
Neo4j tuning information - see the table a couple paragraphs down from the section title.

Fun with HP-UX and glance

Wow it's been a while since I posted... A lot of fun things going on though and I've found plenty of random useful pieces of technical info along the way that I've neglected to share. Here's a small tidbit of info I learned yesterday.

We have had a couple hard to diagnose problems with our primary HP-UX 11.11 server at work recently, so I've been trying to get more acclimated to hp-ux's diagnostic tools. Makes me really miss the plethora of options in linux... Anyway yesterday's tool of the day was gpm, the graphical version of Glance. Our hp-ux admin mentioned I should check it out, and that he had it running fine from his Fedora 14 laptop using ssh + x forwarding. So I tried to fire it up as well (on my F14 laptop) and was greeted with an error something like this:
***** FATAL ERROR *******
Module: ../../../present/cw/ddx.c Line: 2919
Message: FontVal called on unallocated fontset
***** FATAL ERROR *******

I don't remember the exact line (that was just one of the hits I found on google) but that was the basic message. Some of the hits mentioned having to mess with a font server on hp-ux but I was able to start gpm from my colleague's laptop using my login to the hp-ux server, so I was sure it was something on my machine.

A quick query of the rpm's whose package name included "font" that we had installed on our laptops showed me with 70 some packages and him with 200 some packages... I certainly didn't want to wade through all them... but I took a quick look, then fired up the graphical packagekit frontend to install some of the font packages that sounded applicable.

I installed the following packages:
iso8859-2-fonts-common-1.0-24.fc14.noarch
gnu-free-fonts-common-20100919-1.fc14.noarch
gnu-free-serif-fonts-20100919-1.fc14.noarch
gnu-free-mono-fonts-20100919-1.fc14.noarch
gnu-free-sans-fonts-20100919-1.fc14.noarch
gnu-free-fonts-compat-20100919-1.fc14.noarch
iso8859-2-100dpi-fonts-1.0-24.fc14.noarch
iso8859-2-misc-fonts-1.0-24.fc14.noarch
iso8859-2-75dpi-fonts-1.0-24.fc14.noarch
xorg-x11-fonts-ISO8859-1-75dpi-7.2-12.fc14.noarch
xorg-x11-fonts-ISO8859-15-100dpi-7.2-12.fc14.noarch
xorg-x11-fonts-ISO8859-14-100dpi-7.2-12.fc14.noarch
xorg-x11-fonts-ISO8859-2-100dpi-7.2-12.fc14.noarch
xorg-x11-fonts-ISO8859-9-100dpi-7.2-12.fc14.noarch
xorg-x11-fonts-ISO8859-9-75dpi-7.2-12.fc14.noarch
xorg-x11-fonts-ISO8859-15-75dpi-7.2-12.fc14.noarch
xorg-x11-fonts-ISO8859-14-75dpi-7.2-12.fc14.noarch
xorg-x11-fonts-ISO8859-2-75dpi-7.2-12.fc14.noarch
ttmkfdir-3.0.9-32.fc12.i686
xorg-x11-fonts-Type1-7.2-12.fc14.noarch

That did the trick! Maybe some rainy day I will figure out just which one(s) are really needed, but I'm all set for now.

Update: Primoz tracked down the two packages actually needed instead of installing every single one of the ones I did:
xorg-x11-fonts-ISO8859-1-100dpi-7.2-12.fc14.noarch
xorg-x11-fonts-ISO8859-1-75dpi-7.2-12.fc14.noarch