June 17, 2018

Fixing a MythTV performance problem

Filed under: Technical — Tags: , , , , , , , — James Bunton @ 2:17 am

Recently I switched my media server from ext4 on LVM to ZFS. This has mostly been a great success, however I noticed a big problem with MythTV. In the past it would take 1-2sec to start playing video, now it would take 5-60sec. Ouch!

In this post I’ll describe the trouble-shooting techniques I applied, along with all the various things I found and fixed along the way. If you just want to see the solution you can scroll to the end.


January 3, 2018

JavaScript asynchronous functions and error handling

Filed under: Technical — Tags: , — James Bunton @ 9:37 pm

What is asynchronous I/O?

The web services I build spend most of their time doing one of these two classes of things:

  • Processing – Burning CPU cycles calculating things. For example JSON parsing, HTML rendering, image processing, etc.
  • I/O – Waiting for some event external to the CPU/RAM system to finish. For example an HTTP request or DNS request.