I went ahead and created a JIRA and patch: https://issues.apache.org/jira/browse/FLUME-2401
The option is configurable with: agentX.channels.ch1.compressBackupCheckpoint = true As per your recommendation, I used snappy-java. I also considered the snappy and lz4 implementations in Hadoop IO but noticed that the Hadoop IO dependency was removed in https://issues.apache.org/jira/browse/FLUME-1285 Thanks, Abe -- Abraham Fine | Software Engineer (516) 567-2535 BrightRoll, Inc. | Smart Video Advertising | www.brightroll.com On Mon, Jun 9, 2014 at 4:01 PM, Hari Shreedharan <hshreedha...@cloudera.com> wrote: > Hi Abraham, > > Compressing the backup checkpoint is very possible. Since the backup is > rarely read (only if the original one is corrupt on restarts), is it used. > So I think compressing it using something like Snappy would make sense (GZIP > might hit performance). Can you try using snappy-java and see if that gives > good perf and reasonable compression? > > Patches are always welcome. I’d be glad to review and commit it. I would > suggest making the compression optional via configuration so that anyone > with smaller channels don’t end up using CPU for not much gain. > > > Thanks, > Hari > > On Monday, June 9, 2014 at 3:56 PM, Abraham Fine wrote: > > Hello- > > We are using Flume 1.4 with File Channel configured to use a very > large capacity. We keep the checkpoint and backup checkpoint on > separate disks. > > Normally the file channel is mostly empty (<<1% of capacity). For the > checkpoint the disk I/O seems to be very reasonable due to the usage > of a MappedByteBuffer. > > On the other hand, the backup checkpoint seems to be written to disk > in its entirety over and over again, resulting in very high disk > utilization. > > I noticed that, because the checkpoint file is mostly empty, it is > very compressible. I was able to GZIP our checkpoint from 381M to > 386K. I was wondering if it would be possible to always compress the > backup checkpoint before writing it to disk. > > I would be happy to work on a patch to implement this functionality if > there is interest. > > Thanks in Advance, > > -- > Abraham Fine | Software Engineer > (516) 567-2535 > BrightRoll, Inc. | Smart Video Advertising | www.brightroll.com > >
