[jira] [Assigned] (HADOOP-15489) S3Guard to self update on directory listings of S3

["Gabor Bota (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/HADOOP-15489?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Gabor Bota reassigned HADOOP-15489:
-----------------------------------

    Assignee:     (was: Gabor Bota)

> 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: Minor
>
> 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. 



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