the rollInterval will still cause the last 01-17 file to be closed eventually. The way the HDFS sink works with the different files is each unique path is specified by a different BucketWriter object. The sink can hold as many objects as specified by hdfs.maxOpenWorkers (default: 5000), and bucketwriters are only removed when you create the 5001th writer (5001th unique path). However, generally once a writer is closed it is never used again (all of your 1-17 writers will never be used again). To avoid keeping them in the sink's internal list of writers, the idleTimeout is a specified number of seconds in which no data is received by the BucketWriter. After this time, the writer will try to close itself and will then tell the sink to remove it, thus freeing up everything used by the bucketwriter.
So the idleTimeout is just a setting to help limit memory usage by the hdfs sink. The ideal time for it is longer than the maximum time between events (capped at the rollInterval) - if you know you'll receive a constant stream of events you might just set it to a minute or something. Or if you are fine with having multiple files open per hour, you can set it to a lower number; maybe just over the average time between events. For me in just testing, I set it >= rollInterval for the cases when no events are received in a given hour (I'd rather keep the object alive for an extra hour than create files every 30 minutes or something). Hope that was helpful, - Connor On Thu, Jan 17, 2013 at 12:07 PM, Bhaskar V. Karambelkar < [email protected]> wrote: > Say If I have > > a1.sinks.k1.hdfs.path = /flume/events/%y-%m-%d/ > > hdfs.rollInterval=60 > > Now, if there is a file > /flume/events/2013-01-17/flume_XXXXXXXXX.tmp > This file is not ready to be rolled over yet, i.e. 60 seconds are not > up and now it's past 12 midnight, i.e. new day > And events start to be written to > /flume/events/2013-01-18/flume_XXXXXXXX.tmp > > will the file 2013-01-17 never be rolled over, unless I have something > like hdfs.idleTimeout=60 ? > If so how do flume sinks keep track of files they need to rollover > after idealTimeout ? > > In short what's the exact use of idealTimeout parameter ? >
