org.apache.flink.core.fs

Class LimitedConnectionsFileSystem

java.lang.Object

org.apache.flink.core.fs.FileSystem

org.apache.flink.core.fs.LimitedConnectionsFileSystem

@Internal
public class LimitedConnectionsFileSystem
extends FileSystem

A file system that limits the number of concurrently open input streams, output streams, and total streams for a target file system.

This file system can wrap another existing file system in cases where the target file system cannot handle certain connection spikes and connections would fail in that case. This happens, for example, for very small HDFS clusters with few RPC handlers, when a large Flink job tries to build up many connections during a checkpoint.

The filesystem may track the progress of streams and close streams that have been inactive for too long, to avoid locked streams of taking up the complete pool. Rather than having a dedicated reaper thread, the calls that try to open a new stream periodically check the currently open streams once the limit of open streams is reached.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	LimitedConnectionsFileSystem.ConnectionLimitingSettings A simple configuration data object capturing the settings for limited connections.
static class	LimitedConnectionsFileSystem.StreamTimeoutException A special IOException, indicating a timeout in the data output stream.

Nested classes/interfaces inherited from class org.apache.flink.core.fs.FileSystem

FileSystem.WriteMode

Constructor Summary

Constructors

Constructor and Description
LimitedConnectionsFileSystem(FileSystem originalFs, int maxNumOpenStreamsTotal) Creates a new output connection limiting file system.
LimitedConnectionsFileSystem(FileSystem originalFs, int maxNumOpenStreamsTotal, int maxNumOpenOutputStreams, int maxNumOpenInputStreams, long streamOpenTimeout, long streamInactivityTimeout) Creates a new output connection limiting file system, limiting input and output streams with potentially different quotas.
LimitedConnectionsFileSystem(FileSystem originalFs, int maxNumOpenStreamsTotal, long streamOpenTimeout, long streamInactivityTimeout) Creates a new output connection limiting file system.

Method Summary

Modifier and Type	Method and Description
FSDataOutputStream	create(Path f, boolean overwrite, int bufferSize, short replication, long blockSize) Deprecated.
FSDataOutputStream	create(Path f, FileSystem.WriteMode overwriteMode) Opens an FSDataOutputStream to a new file at the given path.
boolean	delete(Path f, boolean recursive) Delete a file.
boolean	exists(Path f) Check if exists.
long	getDefaultBlockSize() Deprecated.
BlockLocation[]	getFileBlockLocations(FileStatus file, long start, long len) Return an array containing hostnames, offset and size of portions of the given file.
FileStatus	getFileStatus(Path f) Return a file status object that represents the path.
Path	getHomeDirectory() Returns the path of the user's home directory in this file system.
FileSystemKind	getKind() Gets a description of the characteristics of this file system.
int	getMaxNumOpenInputStreams() Gets the maximum number of concurrently open input streams.
int	getMaxNumOpenOutputStreams() Gets the maximum number of concurrently open output streams.
int	getMaxNumOpenStreamsTotal() Gets the maximum number of concurrently open streams (input + output).
int	getNumberOfOpenInputStreams() Gets the number of currently open input streams.
int	getNumberOfOpenOutputStreams() Gets the number of currently open output streams.
long	getStreamInactivityTimeout() Gets the milliseconds that a stream may spend not writing any bytes before it is closed as inactive.
long	getStreamOpenTimeout() Gets the number of milliseconds that a opening a stream may wait for availability in the connection pool.
int	getTotalNumberOfOpenStreams() Gets the total number of open streams (input plus output).
URI	getUri() Returns a URI whose scheme and authority identify this file system.
Path	getWorkingDirectory() Returns the path of the file system's current working directory.
boolean	isDistributedFS() Returns true if this is a distributed file system.
FileStatus[]	listStatus(Path f) List the statuses of the files/directories in the given path if the path is a directory.
boolean	mkdirs(Path f) Make the given file and all non-existent parents into directories.
FSDataInputStream	open(Path f) Opens an FSDataInputStream at the indicated Path.
FSDataInputStream	open(Path f, int bufferSize) Opens an FSDataInputStream at the indicated Path.
boolean	rename(Path src, Path dst) Renames the file/directory src to dst.

Methods inherited from class org.apache.flink.core.fs.FileSystem

create, createRecoverableWriter, get, getDefaultFsUri, getLocalFileSystem, getUnguardedFileSystem, initialize, initOutPathDistFS, initOutPathLocalFS

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

LimitedConnectionsFileSystem

public LimitedConnectionsFileSystem(FileSystem originalFs,
                                    int maxNumOpenStreamsTotal)

Creates a new output connection limiting file system.

If streams are inactive (meaning not writing bytes) for longer than the given timeout, then they are terminated as "inactive", to prevent that the limited number of connections gets stuck on only blocked threads.

Parameters:

originalFs - The original file system to which connections are limited.

maxNumOpenStreamsTotal - The maximum number of concurrent open streams (0 means no limit).

LimitedConnectionsFileSystem

public LimitedConnectionsFileSystem(FileSystem originalFs,
                                    int maxNumOpenStreamsTotal,
                                    long streamOpenTimeout,
                                    long streamInactivityTimeout)

Creates a new output connection limiting file system.

If streams are inactive (meaning not writing bytes) for longer than the given timeout, then they are terminated as "inactive", to prevent that the limited number of connections gets stuck on only blocked threads.

Parameters:

originalFs - The original file system to which connections are limited.

maxNumOpenStreamsTotal - The maximum number of concurrent open streams (0 means no limit).

streamOpenTimeout - The maximum number of milliseconds that the file system will wait when no more connections are currently permitted.

streamInactivityTimeout - The milliseconds that a stream may spend not writing any bytes before it is closed as inactive.

LimitedConnectionsFileSystem

public LimitedConnectionsFileSystem(FileSystem originalFs,
                                    int maxNumOpenStreamsTotal,
                                    int maxNumOpenOutputStreams,
                                    int maxNumOpenInputStreams,
                                    long streamOpenTimeout,
                                    long streamInactivityTimeout)

Creates a new output connection limiting file system, limiting input and output streams with potentially different quotas.

If streams are inactive (meaning not writing bytes) for longer than the given timeout, then they are terminated as "inactive", to prevent that the limited number of connections gets stuck on only blocked threads.

Parameters:

originalFs - The original file system to which connections are limited.

maxNumOpenStreamsTotal - The maximum number of concurrent open streams (0 means no limit).

maxNumOpenOutputStreams - The maximum number of concurrent open output streams (0 means no limit).

maxNumOpenInputStreams - The maximum number of concurrent open input streams (0 means no limit).

streamOpenTimeout - The maximum number of milliseconds that the file system will wait when no more connections are currently permitted.

streamInactivityTimeout - The milliseconds that a stream may spend not writing any bytes before it is closed as inactive.

Method Detail

getMaxNumOpenOutputStreams

public int getMaxNumOpenOutputStreams()

Gets the maximum number of concurrently open output streams.

getMaxNumOpenInputStreams

public int getMaxNumOpenInputStreams()

Gets the maximum number of concurrently open input streams.

getMaxNumOpenStreamsTotal

public int getMaxNumOpenStreamsTotal()

Gets the maximum number of concurrently open streams (input + output).

getStreamOpenTimeout

public long getStreamOpenTimeout()

Gets the number of milliseconds that a opening a stream may wait for availability in the connection pool.

getStreamInactivityTimeout

public long getStreamInactivityTimeout()

Gets the milliseconds that a stream may spend not writing any bytes before it is closed as inactive.

getTotalNumberOfOpenStreams

public int getTotalNumberOfOpenStreams()

Gets the total number of open streams (input plus output).

getNumberOfOpenOutputStreams

public int getNumberOfOpenOutputStreams()

Gets the number of currently open output streams.

getNumberOfOpenInputStreams

public int getNumberOfOpenInputStreams()

Gets the number of currently open input streams.

create

public FSDataOutputStream create(Path f,
                                 FileSystem.WriteMode overwriteMode)
                          throws IOException

Description copied from class: FileSystem

Opens an FSDataOutputStream to a new file at the given path.

If the file already exists, the behavior depends on the given WriteMode. If the mode is set to FileSystem.WriteMode.NO_OVERWRITE, then this method fails with an exception.

Specified by:

create in class FileSystem

Parameters:

f - The file path to write to

overwriteMode - The action to take if a file or directory already exists at the given path.

Returns:

The stream to the new file at the target path.

Throws:

IOException - Thrown, if the stream could not be opened because of an I/O, or because a file already exists at that path and the write mode indicates to not overwrite the file.

create

@Deprecated
public FSDataOutputStream create(Path f,
                                             boolean overwrite,
                                             int bufferSize,
                                             short replication,
                                             long blockSize)
                                      throws IOException

Deprecated.

Description copied from class: FileSystem

Opens an FSDataOutputStream at the indicated Path.

This method is deprecated, because most of its parameters are ignored by most file systems. To control for example the replication factor and block size in the Hadoop Distributed File system, make sure that the respective Hadoop configuration file is either linked from the Flink configuration, or in the classpath of either Flink or the user code.

Overrides:

create in class FileSystem

Parameters:

f - the file name to open

overwrite - if a file with this name already exists, then if true, the file will be overwritten, and if false an error will be thrown.

bufferSize - the size of the buffer to be used.

replication - required block replication for the file.

blockSize - the size of the file blocks

Throws:

IOException - Thrown, if the stream could not be opened because of an I/O, or because a file already exists at that path and the write mode indicates to not overwrite the file.

open

public FSDataInputStream open(Path f,
                              int bufferSize)
                       throws IOException

Description copied from class: FileSystem

Opens an FSDataInputStream at the indicated Path.

Specified by:

open in class FileSystem

Parameters:

f - the file name to open

bufferSize - the size of the buffer to be used.

Throws:

IOException

open

public FSDataInputStream open(Path f)
                       throws IOException

Description copied from class: FileSystem

Opens an FSDataInputStream at the indicated Path.

Specified by:

open in class FileSystem

Parameters:

f - the file to open

Throws:

IOException

getKind

public FileSystemKind getKind()

Description copied from class: FileSystem

Gets a description of the characteristics of this file system.

Specified by:

getKind in class FileSystem

isDistributedFS

public boolean isDistributedFS()

Description copied from class: FileSystem

Returns true if this is a distributed file system. A distributed file system here means that the file system is shared among all Flink processes that participate in a cluster or job and that all these processes can see the same files.

Specified by:

isDistributedFS in class FileSystem

Returns:

True, if this is a distributed file system, false otherwise.

getWorkingDirectory

public Path getWorkingDirectory()

Description copied from class: FileSystem

Returns the path of the file system's current working directory.

Specified by:

getWorkingDirectory in class FileSystem

Returns:

the path of the file system's current working directory

getHomeDirectory

public Path getHomeDirectory()

Description copied from class: FileSystem

Returns the path of the user's home directory in this file system.

Specified by:

getHomeDirectory in class FileSystem

Returns:

the path of the user's home directory in this file system.

getUri

public URI getUri()

Description copied from class: FileSystem

Returns a URI whose scheme and authority identify this file system.

Specified by:

getUri in class FileSystem

Returns:

a URI whose scheme and authority identify this file system

getFileStatus

public FileStatus getFileStatus(Path f)
                         throws IOException

Description copied from class: FileSystem

Return a file status object that represents the path.

Specified by:

getFileStatus in class FileSystem

Parameters:

f - The path we want information from

Returns:

a FileStatus object

Throws:

FileNotFoundException - when the path does not exist; IOException see specific implementation

IOException

getFileBlockLocations

public BlockLocation[] getFileBlockLocations(FileStatus file,
                                             long start,
                                             long len)
                                      throws IOException

Description copied from class: FileSystem

Return an array containing hostnames, offset and size of portions of the given file. For a nonexistent file or regions, null will be returned. This call is most helpful with DFS, where it returns hostnames of machines that contain the given file. The FileSystem will simply return an elt containing 'localhost'.

Specified by:

getFileBlockLocations in class FileSystem

Throws:

IOException

listStatus

public FileStatus[] listStatus(Path f)
                        throws IOException

Description copied from class: FileSystem

List the statuses of the files/directories in the given path if the path is a directory.

Specified by:

listStatus in class FileSystem

Parameters:

f - given path

Returns:

the statuses of the files/directories in the given path

Throws:

IOException

delete

public boolean delete(Path f,
                      boolean recursive)
               throws IOException

Description copied from class: FileSystem

Delete a file.

Specified by:

delete in class FileSystem

Parameters:

f - the path to delete

recursive - if path is a directory and set to true, the directory is deleted else throws an exception. In case of a file the recursive can be set to either true or false

Returns:

true if delete is successful, false otherwise

Throws:

IOException

mkdirs

public boolean mkdirs(Path f)
               throws IOException

Description copied from class: FileSystem

Make the given file and all non-existent parents into directories. Has the semantics of Unix 'mkdir -p'. Existence of the directory hierarchy is not an error.

Specified by:

mkdirs in class FileSystem

Parameters:

f - the directory/directories to be created

Returns:

true if at least one new directory has been created, false otherwise

Throws:

IOException - thrown if an I/O error occurs while creating the directory

rename

public boolean rename(Path src,
                      Path dst)
               throws IOException

Description copied from class: FileSystem

Renames the file/directory src to dst.

Specified by:

rename in class FileSystem

Parameters:

src - the file/directory to rename

dst - the new name of the file/directory

Returns:

true if the renaming was successful, false otherwise

Throws:

IOException

exists

public boolean exists(Path f)
               throws IOException

Description copied from class: FileSystem

Check if exists.

Overrides:

exists in class FileSystem

Parameters:

f - source file

Throws:

IOException

getDefaultBlockSize

@Deprecated
public long getDefaultBlockSize()

Deprecated.

Description copied from class: FileSystem

Return the number of bytes that large input files should be optimally be split into to minimize I/O time.

Overrides:

getDefaultBlockSize in class FileSystem

Returns:

the number of bytes that large input files should be optimally be split into to minimize I/O time