[ http://issues.apache.org/jira/browse/HADOOP-387?page=comments#action_12423405 ] Sami Siren commented on HADOOP-387: -----------------------------------
One more note, there were couiple of other places in code where the random was used in the same way, perhaps someone with better understanding of the internals should check them out too. > LocalJobRunner assigns duplicate mapid's > ---------------------------------------- > > Key: HADOOP-387 > URL: http://issues.apache.org/jira/browse/HADOOP-387 > Project: Hadoop > Issue Type: Bug > Components: mapred > Affects Versions: 0.4.0 > Environment: xp, cygwin, jdk1.4.2_12 > Reporter: Sami Siren > Attachments: hadoop-fix-dup-id-0.4.patch, > hadoop-fix-dup-id-trunk.patch > > > While hunting down nutch issue NUTCH-266 i discovered that id's are generated > with following fragment of code: > private String newId() { > return Integer.toString(Math.abs(new Random().nextInt()),36); > } > and the related Javadoc: > " > public Random() > Creates a new random number generator. Its seed is initialized to a value > based on the current time: > public Random() { this(System.currentTimeMillis()); } > Two Random objects created within the same millisecond will have the same > sequence of random numbers. > " > it appears that in this case there are more than one Random pobject generated > at the same millisecond and id's are > no longer unique. -- This message is automatically generated by JIRA. - If you think it was sent incorrectly contact one of the administrators: http://issues.apache.org/jira/secure/Administrators.jspa - For more information on JIRA, see: http://www.atlassian.com/software/jira
