Question

I have written a native hadoop compression codec. To let it work with hadoop I need to compile native (C code) it to libhadoop.so.

How can I achieve this?

Answer 1

You don’t need to compile this into libhadoop.so:

• Compile your own .so and distribute to your cluster nodes (into the same directory as the current libhadoop.so
• I assume you’ve also written your own CompressionCodec (similar to GzipCodec) – add a static block to this code which tries to load the library using System.loadLibrary("mylibrary"); (for a lib named libmylibrary.so).
• Amend your cluster configuration to include your new compression codec class in the registered list of codecs (amend the io.compression.codecs configuration property):
• Restart your task trackers

As a reference, you can follow the implementation and configuration notes for the Google Snappy codec:

• http://code.google.com/p/hadoop-snappy/