[HADOOP-8406] CompressionCodecFactory.CODEC_PROVIDERS iteration is thread-unsafe

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 2.0.0-alpha
• Fix Version/s: 2.0.2-alpha
• Component/s: io
• Hadoop Flags: Reviewed
• Assignee: Todd Lipcon
• Reporter: Todd Lipcon
• Created: 17/May/12 00:56
• Updated: 11/Oct/12 17:45
• Resolved: 17/May/12 04:28

Description

CompressionCodecFactory defines CODEC_PROVIDERS as:

  private static final ServiceLoader<CompressionCodec> CODEC_PROVIDERS =
    ServiceLoader.load(CompressionCodec.class);

but this is a lazy collection which is thread-unsafe to iterate. We either need to synchronize when we iterate over it, or we need to materialize it during class-loading time by copying to a non-lazy collection