steveloughran commented on pull request #2584: URL: https://github.com/apache/hadoop/pull/2584#issuecomment-759582014
I'm thinking we should be more ambitious in read policy than just "fadvise", because we can then use it as a declaration for the input streams to tune all their params, eg. buffer sizing, whether to do async prefetch. Then we could allow stores to support not-just seek policies, but declare what you were planning to read, e.g. "impala-bytebuffer", to mean "I'm using impala with the bytebuffer" example` opt(fs.openfile.read.policy, "impala-vectored, impala, vectored,random")` to mean "optimise for impala for vectored IO, then generic vectored IO, then generic random IO". Store implementors would get to make their own decisions as to what to set based on profiling &c. We'd need the applications to set policy on `openFile()` -so would need to know what names to use. That we can discuss with them, maybe by predefining some options which *may* be supported ---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: [email protected] --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
