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Steve Loughran commented on HADOOP-15489: ----------------------------------------- No benchmark data here; just realised the issue exists if you are doing things like treewalks of a filesystem not yet imported into S3Guard. Although the S3 LIST calls get the data of the descendants, the DDB table isn't updated. This is underperformant > S3Guard to self update on directory listings of S3 > -------------------------------------------------- > > Key: HADOOP-15489 > URL: https://issues.apache.org/jira/browse/HADOOP-15489 > Project: Hadoop Common > Issue Type: Sub-task > Components: fs/s3 > Affects Versions: 3.1.0 > Environment: s3guard > Reporter: Steve Loughran > Priority: Major > > S3Guard updates its table on a getFileStatus call, but not on a directory > listing. > While this makes directory listings faster (no need to push out an update), > it slows down subsequent queries of the files, such as a sequence of: > {code} > statuses = s3a.listFiles(dir) > for (status: statuses) { > if (status.isFile) { > try(is = s3a.open(status.getPath())) { > ... do something > } > } > {code} > this is because the open() is doing the getFileStatus check, even after the > listing. > Updating the DDB tables after a listing would give those reads a speedup, > albeit at the expense of initiating a (bulk) update in the list call. Of > course, we could consider making that async, though that design (essentially > a write-buffer) would require the buffer to be checked in the reads too. -- This message was sent by Atlassian JIRA (v7.6.3#76005) --------------------------------------------------------------------- To unsubscribe, e-mail: common-issues-unsubscr...@hadoop.apache.org For additional commands, e-mail: common-issues-h...@hadoop.apache.org