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ASF GitHub Bot logged work on SSHD-1220: ---------------------------------------- Author: ASF GitHub Bot Created on: 30/Oct/21 18:19 Start Date: 30/Oct/21 18:19 Worklog Time Spent: 10m Work Description: tomaswolf commented on pull request #207: URL: https://github.com/apache/mina-sshd/pull/207#issuecomment-955572789 All right; thanks. Here it is again without config. -- 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. To unsubscribe, e-mail: dev-unsubscr...@mina.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org Issue Time Tracking ------------------- Worklog Id: (was: 672386) Time Spent: 2h 20m (was: 2h 10m) > SFTP: too many LSTAT calls > -------------------------- > > Key: SSHD-1220 > URL: https://issues.apache.org/jira/browse/SSHD-1220 > Project: MINA SSHD > Issue Type: Improvement > Affects Versions: 2.7.0 > Reporter: Thomas Wolf > Assignee: Thomas Wolf > Priority: Major > Time Spent: 2h 20m > Remaining Estimate: 0h > > While looking at an alternate solution for SSHD-1217 I noticed that the > {{AbstractSftpSubsystemHelper}} makes several LSTAT calls for a single > {{FileSystem.readAttributes()}} invocation. > Basically it makes one LSTAT call per supported attributes view; only to > collect the returned items then in one single map anyway. > This doesn't make any sense. SFTP file attributes are a single, defined > structure. If {{AbstractSftpSubsystemHelper.getAttributes()}} needs to > collect all these different views ({{BasicFileAttributes}}, > {{PosixFileAttributes}}, and so on) on these underlying SFTP attributes, then > all these views should build upon the same single {{SftpClient.Attributes}} > gotten exactly _once_. > This could be solved with careful temporary caching of SFTP attributes on the > {{SftpPath}} once read while in > {{AbstractSftpSubsystemHelper.getAttributes()}} and clearing that cache at > the end. > The problem is more general, though. The code in several places makes > up-front checks whether a file exists, is a directory, and so on. This is a > questionable pattern anyway, since the result of a {{Files.exists()}} is > outdated immediately; one cannot rely on the file being still there on the > next access. With an {{SftpPath}}, this {{exists()}} call is an (L)STAT > remote call getting the attributes. Now look at > {{AbstractSftpSubsystemHelper.resolveFileAttributes}}: here getting the > attributes themselves is so guarded, so it makes at least _two_ LSTAT calls. > This should also be improved. -- This message was sent by Atlassian Jira (v8.3.4#803005) --------------------------------------------------------------------- To unsubscribe, e-mail: dev-unsubscr...@mina.apache.org For additional commands, e-mail: dev-h...@mina.apache.org