We are currently evaluating the consequences of migrating our application from Java 1.4 to Java 5. While initial tests revealed only simple issues (like variables called enum etc.) we are now seeing a much more severe problem: Random VM crashes.

Currently we only see this on Linux (Kernel 2.4) only, however even there we cannot reliably reproduce the problem. On a single machine we have seen two crashes in a week. Notably the application was not being used, it was just started and waiting for user input. Some background threads are running in this situation, however they do not do any work, either. They just poll some database tables for external changes, but there were none.

All of a sudden a VM would crash, leaving a hs_err_pid1234.txt behind. This is what they look like (shortened):

#
# An unexpected error has been detected by HotSpot Virtual Machine:
#
#  SIGSEGV (0xb) at pc=0x402989b9, …

Another one of my coworkers announced his departure from the company today. That makes three of us in two weeks.

My last day is the 10th. I'll be spending the morning at Y! taking care of my final business. After that I'm heading over to MySQL camp over at the Google campus.

Right now a couple cop cars and lockheed martin security have some guy who was riding a bicycle on first ave. I have a feeling he wandered onto government property accidentally. Hopefully he doesn't get a trip to Guantanamo for it.

XenSource Announces High Performance Virtualization of Microsoft Windows and Linux Based on the Xen Hypervisor, XenSource (Press Release)

Simula Labs Launches Hosted Delivery Platform to Enable Enterprise Open Source Adoption, Simula Labs (Press Release)

Compiere Highlights Partner Achievements, Outlines Framework for Company and Product Direction for 2007, Compiere (Press Release)

Currenex Announces OpenSTP/FX Industry Initiative, Currenex (Press Release)

Alfresco Joins the ODF Alliance, Alfresco Software (Press Release) …

Anyone who's been to an open source conference this year has probably been to the Apress Publishing booth. If you have, undoubtedly, you've seen the yellow and black Apress buttons with the hysterical slogans on them. Myself, have a few Apress connections of my own, I have a few of my favorite ones at home, and the local PHP and Linux User Groups know the buttons because I pass them out when I go to the meetings. The buttons are the brilliant brainchild of Apress chief, Gary Cornell. Some of my favorite slogans:

• "I rarely come out of my shell environment"
• "Enter any 128 bit prime number to continue"
• "Do not offend the geeks, for they are the keepers of your passwords"

Julie Miller, from Apress, has volunteered to have buttons made for MySQL Camp, coming up this Friday through Sunday in …

Until recently, the MySQL databases I work with contain data that can be retrieved from other sources. Most of the data is either batched in from flat files or another database. It would be inconvenient to reload a couple months worth of data, but since these databases are not mission critical, the business could operate without them for a couple days. Lately, we've been implementing some semi-critical systems that rely on a somewhat expedient recovery.

The requirements for the project were that the database must remain up during the backup and losing a day's worth of data was acceptable. All of my regular Oracle readers are cringing at the moment, but hey, that was the rules I was working with.

My first thought was to use mysqlhotcopy because it backed up the actual physical files. However, mysqlhotcopy only allows you to backup MyISAM tables and we extensively use InnoDB.

My next choice was mysqldump. …

MySQL Connector/Net 5.0.2 Beta has been released.  MySQL Connector/Net is an all-managed ADO.Net provider for MySQL.  While this release is suitable for any version of MySQL, it is strongly encouraged that this release not be used on any production data. 

It is now available in source and binary form from the Connector/Net download pages at http://dev.mysql.com/downloads/connector/net/5.0.html and mirror sites (note that not all mirror sites may be up to date at this point of time - if you can't find this version on some mirror, please try again later or choose another download site.)

Changes in this release (changelog):

Bugs fixed

• Bug #23268 System.FormatException when invoking procedure with ENUM input parameter
• Bug #23538 Exception thrown when GetSchemaTable is called and …

A Materialised View (MV) is the precalculated (materialised) result of a query. Unlike a simple VIEW the result of a Materialised View is stored somewhere, generally in a table. Materialised Views are used when immediate response is needed and the query where the Materialised View bases on would take to long to produce a result. Materialised Views have to be refreshed once in a while. It depends on the requirements how often a Materialised View is refreshed and how actual its content is. Basically a Materialised View can be refreshed immediately or deferred, it can be refreshed fully or to a certain point in time. MySQL does not provide Materialised Views by itself. But it is easy to build Materialised Views yourself.

I've done a multitude of benchmarks using various 2.6 IO schedulers. Hands down the Deadline I/O scheduler is the best for INNODB traffic or RANDOM IO. I use to have all this benchmark information in excel worksheets, but lost it when I left Friendster.

Here is how to figure out what IO scheduler your using in Linux 2.6

dmesg |grep -i sched

In most cases your probibly set up to use the cfq io scheduler. Change it to deadline in your PXE, lilo, or grub settings.


For example:

# For booting GNU/Hurd
title GNU/Hurd
root (hd0,0)
kernel /boot/gnumach.gz root=hd0s1
module /boot/serverboot.gz

append to it
kernel /boot/wtfe root=wtfe elevator=deadline

Thanks Peter N. for the linux config info!

Since Oracle announced their fork of Red Hat Linux most of the news coverage has been about the business implications for Red Hat and other Linux vendors.  To be honest, I don't think the impact is all that significant.  Decisions are made by one guy at Oracle (much to the chagrin of many of his executives) and if Larry decides he wants to fork with Red Hat, then he tells his guys to get it done.  So what do they do?  They post CentOS for download on the Oracle web site and call it their own.  And as part of that, Oracle is now distributing MySQL, which is ironic, but nonetheless appreciated. 

Maybe Oracle customers think that Oracle can do a better job supporting their OS than the guys who wrote …