[jira] [Commented] (HADOOP-13430) Optimize getFileStatus in S3A
[ https://issues.apache.org/jira/browse/HADOOP-13430?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel=17077221#comment-17077221 ] Steve Loughran commented on HADOOP-13430: - Looking at this in HADOOP-13230. * isDirectory/isFile will only do the explicit probes they need * going to add a hint inside about whether a file or dir is expected (e.g mkdirs will look for dirs), and so order the probes appropriately > Optimize getFileStatus in S3A > - > > Key: HADOOP-13430 > URL: https://issues.apache.org/jira/browse/HADOOP-13430 > Project: Hadoop Common > Issue Type: Sub-task > Components: fs/s3 >Affects Versions: 2.8.0 >Reporter: Steven K. Wong >Assignee: Steven K. Wong >Priority: Minor > Attachments: HADOOP-13430.001.WIP.patch > > > Currently, S3AFileSystem.getFileStatus(Path f) sends up to 3 requests to S3 > when pathToKey(f) = key = "foo/bar" is a directory: > 1. HEAD key=foo/bar \[continue if not found] > 2. HEAD key=foo/bar/ \[continue if not found] > 3. LIST prefix=foo/bar/ delimiter=/ max-keys=1 > My experience (and generally true, I reckon) is that almost all directories > are nonempty directories without a "fake directory" file (e.g. "foo/bar/"). > Under this condition, request #2 is mostly unhelpful; it only slows down > getFileStatus. Therefore, I propose swapping the order of requests #2 and #3. > The swapped HEAD request will be skipped in practically all cases. > Furthermore, when key = "foo/bar" is a nonempty directory that contains a > "fake directory" file (in addition to actual files), getFileStatus currently > returns an S3AFileStatus with isEmptyDirectory=true, which is wrong. Swapping > will fix this. The swapped LIST request will use max-keys=2 to determine > isEmptyDirectory correctly. (Removing the delimiter from the LIST request > should make the logic a little simpler than otherwise.) > Note that key = "foo/bar/" has the same problem with isEmptyDirectory. To fix > it, I propose skipping request #1 when key ends with "/". The price is this > will, for an empty directory, replace a HEAD request with a LIST request > that's generally more taxing on S3. -- This message was sent by Atlassian Jira (v8.3.4#803005) - To unsubscribe, e-mail: common-issues-unsubscr...@hadoop.apache.org For additional commands, e-mail: common-issues-h...@hadoop.apache.org
[jira] [Commented] (HADOOP-13430) Optimize getFileStatus in S3A
[ https://issues.apache.org/jira/browse/HADOOP-13430?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel=16903962#comment-16903962 ] Steve Loughran commented on HADOOP-13430: - # for create file we can skip the GET object when overwrite=true # for list operations we should attempt the list and only fall back to the HEAD calls if that fails item #2 should make a big difference to treewalks > Optimize getFileStatus in S3A > - > > Key: HADOOP-13430 > URL: https://issues.apache.org/jira/browse/HADOOP-13430 > Project: Hadoop Common > Issue Type: Sub-task > Components: fs/s3 >Affects Versions: 2.8.0 >Reporter: Steven K. Wong >Assignee: Steven K. Wong >Priority: Minor > Attachments: HADOOP-13430.001.WIP.patch > > > Currently, S3AFileSystem.getFileStatus(Path f) sends up to 3 requests to S3 > when pathToKey(f) = key = "foo/bar" is a directory: > 1. HEAD key=foo/bar \[continue if not found] > 2. HEAD key=foo/bar/ \[continue if not found] > 3. LIST prefix=foo/bar/ delimiter=/ max-keys=1 > My experience (and generally true, I reckon) is that almost all directories > are nonempty directories without a "fake directory" file (e.g. "foo/bar/"). > Under this condition, request #2 is mostly unhelpful; it only slows down > getFileStatus. Therefore, I propose swapping the order of requests #2 and #3. > The swapped HEAD request will be skipped in practically all cases. > Furthermore, when key = "foo/bar" is a nonempty directory that contains a > "fake directory" file (in addition to actual files), getFileStatus currently > returns an S3AFileStatus with isEmptyDirectory=true, which is wrong. Swapping > will fix this. The swapped LIST request will use max-keys=2 to determine > isEmptyDirectory correctly. (Removing the delimiter from the LIST request > should make the logic a little simpler than otherwise.) > Note that key = "foo/bar/" has the same problem with isEmptyDirectory. To fix > it, I propose skipping request #1 when key ends with "/". The price is this > will, for an empty directory, replace a HEAD request with a LIST request > that's generally more taxing on S3. -- This message was sent by Atlassian JIRA (v7.6.14#76016) - To unsubscribe, e-mail: common-issues-unsubscr...@hadoop.apache.org For additional commands, e-mail: common-issues-h...@hadoop.apache.org
[jira] [Commented] (HADOOP-13430) Optimize getFileStatus in S3A
[ https://issues.apache.org/jira/browse/HADOOP-13430?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel=16236409#comment-16236409 ] Steve Loughran commented on HADOOP-13430: - Interesting thought that we could actually override isDirectory(path) and isFile(path) and so actually fail fast if the conditions not met. isDirectory: do a LIST path first, then HEAD path +"/". isFile(), HEAD path & return true/map FNFE to false without bothering with the two other checks > Optimize getFileStatus in S3A > - > > Key: HADOOP-13430 > URL: https://issues.apache.org/jira/browse/HADOOP-13430 > Project: Hadoop Common > Issue Type: Sub-task > Components: fs/s3 >Affects Versions: 2.8.0 >Reporter: Steven K. Wong >Assignee: Steven K. Wong >Priority: Minor > Attachments: HADOOP-13430.001.WIP.patch > > > Currently, S3AFileSystem.getFileStatus(Path f) sends up to 3 requests to S3 > when pathToKey(f) = key = "foo/bar" is a directory: > 1. HEAD key=foo/bar \[continue if not found] > 2. HEAD key=foo/bar/ \[continue if not found] > 3. LIST prefix=foo/bar/ delimiter=/ max-keys=1 > My experience (and generally true, I reckon) is that almost all directories > are nonempty directories without a "fake directory" file (e.g. "foo/bar/"). > Under this condition, request #2 is mostly unhelpful; it only slows down > getFileStatus. Therefore, I propose swapping the order of requests #2 and #3. > The swapped HEAD request will be skipped in practically all cases. > Furthermore, when key = "foo/bar" is a nonempty directory that contains a > "fake directory" file (in addition to actual files), getFileStatus currently > returns an S3AFileStatus with isEmptyDirectory=true, which is wrong. Swapping > will fix this. The swapped LIST request will use max-keys=2 to determine > isEmptyDirectory correctly. (Removing the delimiter from the LIST request > should make the logic a little simpler than otherwise.) > Note that key = "foo/bar/" has the same problem with isEmptyDirectory. To fix > it, I propose skipping request #1 when key ends with "/". The price is this > will, for an empty directory, replace a HEAD request with a LIST request > that's generally more taxing on S3. -- This message was sent by Atlassian JIRA (v6.4.14#64029) - To unsubscribe, e-mail: common-issues-unsubscr...@hadoop.apache.org For additional commands, e-mail: common-issues-h...@hadoop.apache.org
