Sean Owen created CRUNCH-575: -------------------------------- Summary: DistributedPipeline temp dir choice can collide with itself Key: CRUNCH-575 URL: https://issues.apache.org/jira/browse/CRUNCH-575 Project: Crunch Issue Type: Bug Components: Core Affects Versions: 0.12.0 Reporter: Sean Owen Assignee: Josh Wills Priority: Minor
We've observed that Crunch jobs can fail because the output temp dir already exists: {code} 2015-04-02 04:45:49,208 INFO org.apache.crunch.hadoop.mapreduce.lib.jobcontrol.CrunchControlledJob: org.apache.hadoop.mapred.FileAlreadyExistsException: Output directory /tmp/crunch-686245394/p2/output already exists at org.apache.hadoop.mapreduce.lib.output.FileOutputFormat.checkOutputSpecs(FileOutputFormat.java:132) {code} One possible cause is the choice of random directory name, which is based on a random nonnegative 32-bit int. The chance of collision is more than 50% at about 55,000 temp dirs, which is not unimaginable. A suggested fix, at least for that theoretical cause, is to generate a much larger random value. 64 bits should put this firmly in the realm of extremely improbably (billions, not tens of thousands). (HT [~wilfreds] / CC [~tomwhite]) -- This message was sent by Atlassian JIRA (v6.3.4#6332)