Tuning Java Garbage Collection

I recently completed a garbage collection exercise on a variety of applications. In all, twenty WebLogic application clusters were tuned. A dozen of these are large busy application clusters. These provide a mix of Web Applications and Web Services. Tuning garbage collection is a matter of trade-offs. Large heaps take longer to garbage collect. Small… Continue reading Tuning Java Garbage Collection

Securing TLS

A StackExchange question on using HAProxy’s capture feature to pass data from TCP mode to HTTP mode prompted me to update my SSL configuration. This was intended to get an A+ rating from SSL Labs by sending non-SNI capable clients to a server with weaker ciphers. This was to enable clients on WinXP/IE8, Java 6,… Continue reading Securing TLS

WordPress Tuning

I’ve done a little tuning to my WordPress setup. To keep up to date, I’ve switched from the Ubuntu installation to a downloaded installation under /opt/wordpress. This is owned by my user and served by Apache running as www-data. Updates are done using the SFTP method.

Command Line Arguments in Python

When I need a new tool, I often code it in Python. Often, command-line options are useful. Sometimes it is possible to have a fixed set of parameters, but this is not very flexible. Fortunately, Python has standard libraries to handle parsing command lines. Three libraries provide varying capabilities. Some of the systems I run on have… Continue reading Command Line Arguments in Python

MX on a Dynamic IP Address

I often see posts asking about running a mail server on a Dynamic IP address. Twenty years ago I started running my server on a dynamic IP address. However, times have changed, and it is more difficult to do so. Stil, there are mail server roles that work reasonably well on a dynamic IP address.  

Tuning Linux CPU Performance

A recent kernel change broke my CPU performance tuning. I have an AMD processor that presents 4 cores to the kernel. The process in this article should work for Intel processors although the governors and CPU settings tree may be different. Different kernels may also have different settings. The current kernel allows setting the governor per… Continue reading Tuning Linux CPU Performance

Adding SHA-2 to tinyca

Google has announced a sunset for SHA-1 certificate signatures in Chrome. SHA-2 (aka SHA-256, SHA-384, and SHA-512) is the remaining option for certificate signatures. I decided to upgrade my certificates to SHA-2 (256 bits). However, when I tried to use tinyca2 to generate a SHA-2 certificate, I found it was not supported. As tinyca2 is… Continue reading Adding SHA-2 to tinyca

Disable TraceClassUnloading in Java 6

I recently discovered logs filling up with log messages for classes being unloaded during garbage collection. After a little research, I found that the TraceClassUnloading switch gets turned on by the Xloggc switch. After a little testing, I found that this can be resolved by adding the argument -XX:-TraceClassUnloading after the -Xloggc argument.