[GIRAPH-216] NullWritable as VertexData, EdgeData or MessageData should be allowed

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 1.0.0
• Assignee: jvdl
• Reporter: jvdl
• Created: 22/Jun/12 21:22
• Updated: 05/Jul/12 19:52
• Resolved: 05/Jul/12 18:53

Description

When using NullWritable as VertexData, EdgeData or MessageData, an error occurs. This happens because the constructor of NullWritable is private, so ReflectionUtils.newInstance() fails. The solution is checking for NullWritable separately, and then returning NullWritable.get() instead of a new class. This can save very large amounts of memory, since NullWritable is a singleton.

This was reported on the mailing list, but never fixed: http://mail-archives.apache.org/mod_mbox/incubator-giraph-user/201112.mbox/[e-mail]%3E