Mikhail Pryakhin created HADOOP-15358:
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Summary: SFTPConnectionPool connections leakage
Key: HADOOP-15358
URL: https://issues.apache.org/jira/browse/HADOOP-15358
Project: Hadoop Common
Issue Type: Bug
Components: fs
Affects Versions: 3.0.0
Reporter: Mikhail Pryakhin
Methods of SFTPFileSystem operate on poolable ChannelSftp instances, thus some
methods of SFTPFileSystem are chained together resulting in establishing
multiple connections to the SFTP server to accomplish one compound action,
those methods are listed below:
# mkdirs method
the public mkdirs method acquires a new ChannelSftp from the pool [1]
and then recursively creates directories, checking for the directory existence
beforehand by calling the method exists[2] which delegates to the
getFileStatus(ChannelSftp channel, Path file) method [3] and so on until it
ends up in returning the FilesStatus instance [4]. The resource leakage occurs
in the method getWorkingDirectory which calls the getHomeDirectory method [5]
which in turn establishes a new connection to the sftp server instead of using
an already created connection. As the mkdirs method is recursive this results
in creating a huge number of connections.
# open method [6] This method returns an instance of FSDataInputStream which
consumes SFTPInputStream instance which doesn't return an acquired ChannelSftp
instance back to the pool but instead it closes it[7]. This leads to
establishing another connection to an SFTP server when the next method is
called on the FileSystem instance.
[1]
https://github.com/apache/hadoop/blob/736ceab2f58fb9ab5907c5b5110bd44384038e6b/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/sftp/SFTPFileSystem.java#L658
[2]
https://github.com/apache/hadoop/blob/736ceab2f58fb9ab5907c5b5110bd44384038e6b/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/sftp/SFTPFileSystem.java#L321
[3]
https://github.com/apache/hadoop/blob/736ceab2f58fb9ab5907c5b5110bd44384038e6b/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/sftp/SFTPFileSystem.java#L202
[4]
https://github.com/apache/hadoop/blob/736ceab2f58fb9ab5907c5b5110bd44384038e6b/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/sftp/SFTPFileSystem.java#L290
[5]
https://github.com/apache/hadoop/blob/736ceab2f58fb9ab5907c5b5110bd44384038e6b/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/sftp/SFTPFileSystem.java#L640
[6]
https://github.com/apache/hadoop/blob/736ceab2f58fb9ab5907c5b5110bd44384038e6b/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/sftp/SFTPFileSystem.java#L504
[7]
https://github.com/apache/hadoop/blob/736ceab2f58fb9ab5907c5b5110bd44384038e6b/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/sftp/SFTPInputStream.java#L123
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