HDFS Capacity

How much data can our Hadoop instance hold, and how can I make it hold more? Architectural Background Hadoop is a lot of things, and one of those is a distributed, abstracted file system. It’s called HDFS (for “hadoop distributed file system,” maybe), and it has its uses. HDFS isn’t a file system in the …

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Logs are like onions

Or, What underlying implementation is clojure.tools.logging using? Today I want to change the logging configuration of a Clojure program. Where is that configuration located? Changing the obvious resources/log4j.properties doesn’t seem to change the program’s behavior. The program uses clojure.tools.logging, but that’s a wrapper around four different underlying implementations. Each of those implementations has its own ideas …

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Testing akka: turn on debug

Testing is easier when you can see what messages are received by your actors. To do this, add logging to your real code, and then change your configuration. This post shows how to hard-code some debugging configuration for testing purposes. Step 1: put logging into your receive method, by wrapping your existing receive definition in …

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Stupid git tricks: transferring part of one git repo to another

Reference post. Don’t expect this to be interesting. We had a particular subdirectory of a repository (repoA) that really belonged in repoB. The goal is to transfer all files and history from repoA to repoB, permanently. Thanks to Nikolai in this blog post, the move isn’t too bad. I’m not going to repeat his instructions. …

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Setting up an Android project in IntelliJ Idea

And there was pain… I imported an existing Android project into IntelliJ Idea Community Edition 10.5.1. Some things started complaining “Please select Android SDK.” The help pages are out of date; they say to do this in the Android facet settings. It isn’t there. Here is the secret do-things-right button: Module settings (ctrl-alt-shift-S), then pick …

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