Package org.apache.flink.runtime.state.filesystem

Class FsStateBackend

  • All Implemented Interfaces:
    Serializable, CheckpointStorage, ConfigurableStateBackend, StateBackend
    @Deprecated
@PublicEvolving
public class FsStateBackend
extends AbstractFileStateBackend
implements ConfigurableStateBackend
    Deprecated.
    IMPORTANT FsStateBackend is deprecated in favor of HashMapStateBackend and FileSystemCheckpointStorage. This change does not affect the runtime characteristics of your Jobs and is simply an API change to help better communicate the ways Flink separates local state storage from fault tolerance. Jobs can be upgraded without loss of state. If configuring your state backend via the StreamExecutionEnvironment please make the following changes. 
    
 		StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment();
 		env.setStateBackend(new HashMapStateBackend());
 		env.getCheckpointConfig().setCheckpointStorage("hdfs:///checkpoints");

    If you are configuring your state backend via the flink-conf.yaml please make the following changes set your state backend type to "hashmap" state.backend.type: hashmap.

    This state backend holds the working state in the memory (JVM heap) of the TaskManagers. The state backend checkpoints state as files to a file system (hence the backend's name).

    Each checkpoint individually will store all its files in a subdirectory that includes the checkpoint number, such as hdfs://namenode:port/flink-checkpoints/chk-17/.

    State Size Considerations

    Working state is kept on the TaskManager heap. If a TaskManager executes multiple tasks concurrently (if the TaskManager has multiple slots, or if slot-sharing is used) then the aggregate state of all tasks needs to fit into that TaskManager's memory.

    This state backend stores small state chunks directly with the metadata, to avoid creating many small files. The threshold for that is configurable. When increasing this threshold, the size of the checkpoint metadata increases. The checkpoint metadata of all retained completed checkpoints needs to fit into the JobManager's heap memory. This is typically not a problem, unless the threshold getMinFileSizeThreshold() is increased significantly.

    Persistence Guarantees

    Checkpoints from this state backend are as persistent and available as filesystem that is written to. If the file system is a persistent distributed file system, this state backend supports highly available setups. The backend additionally supports savepoints and externalized checkpoints.

    Configuration

    As for all state backends, this backend can either be configured within the application (by creating the backend with the respective constructor parameters and setting it on the execution environment) or by specifying it in the Flink configuration.

    If the state backend was specified in the application, it may pick up additional configuration parameters from the Flink configuration. For example, if the backend if configured in the application without a default savepoint directory, it will pick up a default savepoint directory specified in the Flink configuration of the running job/cluster. That behavior is implemented via the configure(ReadableConfig, ClassLoader) method.

    See Also:
    Serialized Form

    • Constructor Detail

      • FsStateBackend

        public FsStateBackend​(String checkpointDataUri)
        Deprecated.
        Creates a new state backend that stores its checkpoint data in the file system and location defined by the given URI.

        A file system for the file system scheme in the URI (e.g., 'file://', 'hdfs://', or 'S3://') must be accessible via FileSystem.get(URI).

        For a state backend targeting HDFS, this means that the URI must either specify the authority (host and port), or that the Hadoop configuration that describes that information must be in the classpath.

        Parameters:
        checkpointDataUri - The URI describing the filesystem (scheme and optionally authority), and the path to the checkpoint data directory.

      • FsStateBackend

        public FsStateBackend​(String checkpointDataUri,
                      boolean asynchronousSnapshots)
        Deprecated.
        Creates a new state backend that stores its checkpoint data in the file system and location defined by the given URI.

        A file system for the file system scheme in the URI (e.g., 'file://', 'hdfs://', or 'S3://') must be accessible via FileSystem.get(URI).

        For a state backend targeting HDFS, this means that the URI must either specify the authority (host and port), or that the Hadoop configuration that describes that information must be in the classpath.

        Parameters:
        checkpointDataUri - The URI describing the filesystem (scheme and optionally authority), and the path to the checkpoint data directory.
        asynchronousSnapshots - This parameter is only there for API compatibility. Checkpoints are always asynchronous now.

      • FsStateBackend

        public FsStateBackend​(org.apache.flink.core.fs.Path checkpointDataUri)
        Deprecated.
        Creates a new state backend that stores its checkpoint data in the file system and location defined by the given URI.

        A file system for the file system scheme in the URI (e.g., 'file://', 'hdfs://', or 'S3://') must be accessible via FileSystem.get(URI).

        For a state backend targeting HDFS, this means that the URI must either specify the authority (host and port), or that the Hadoop configuration that describes that information must be in the classpath.

        Parameters:
        checkpointDataUri - The URI describing the filesystem (scheme and optionally authority), and the path to the checkpoint data directory.

      • FsStateBackend

        public FsStateBackend​(org.apache.flink.core.fs.Path checkpointDataUri,
                      boolean asynchronousSnapshots)
        Deprecated.
        Creates a new state backend that stores its checkpoint data in the file system and location defined by the given URI.

        A file system for the file system scheme in the URI (e.g., 'file://', 'hdfs://', or 'S3://') must be accessible via FileSystem.get(URI).

        For a state backend targeting HDFS, this means that the URI must either specify the authority (host and port), or that the Hadoop configuration that describes that information must be in the classpath.

        Parameters:
        checkpointDataUri - The URI describing the filesystem (scheme and optionally authority), and the path to the checkpoint data directory.
        asynchronousSnapshots - This parameter is only there for API compatibility. Checkpoints are always asynchronous now.

      • FsStateBackend

        public FsStateBackend​(URI checkpointDataUri)
        Deprecated.
        Creates a new state backend that stores its checkpoint data in the file system and location defined by the given URI.

        A file system for the file system scheme in the URI (e.g., 'file://', 'hdfs://', or 'S3://') must be accessible via FileSystem.get(URI).

        For a state backend targeting HDFS, this means that the URI must either specify the authority (host and port), or that the Hadoop configuration that describes that information must be in the classpath.

        Parameters:
        checkpointDataUri - The URI describing the filesystem (scheme and optionally authority), and the path to the checkpoint data directory.

      • FsStateBackend

        public FsStateBackend​(URI checkpointDataUri,
                      @Nullable
                      URI defaultSavepointDirectory)
        Deprecated.
        Creates a new state backend that stores its checkpoint data in the file system and location defined by the given URI. Optionally, this constructor accepts a default savepoint storage directory to which savepoints are stored when no custom target path is give to the savepoint command.

        A file system for the file system scheme in the URI (e.g., 'file://', 'hdfs://', or 'S3://') must be accessible via FileSystem.get(URI).

        For a state backend targeting HDFS, this means that the URI must either specify the authority (host and port), or that the Hadoop configuration that describes that information must be in the classpath.

        Parameters:
        checkpointDataUri - The URI describing the filesystem (scheme and optionally authority), and the path to the checkpoint data directory.
        defaultSavepointDirectory - The default directory to store savepoints to. May be null.

      • FsStateBackend

        public FsStateBackend​(URI checkpointDataUri,
                      boolean asynchronousSnapshots)
        Deprecated.
        Creates a new state backend that stores its checkpoint data in the file system and location defined by the given URI.

        A file system for the file system scheme in the URI (e.g., 'file://', 'hdfs://', or 'S3://') must be accessible via FileSystem.get(URI).

        For a state backend targeting HDFS, this means that the URI must either specify the authority (host and port), or that the Hadoop configuration that describes that information must be in the classpath.

        Parameters:
        checkpointDataUri - The URI describing the filesystem (scheme and optionally authority), and the path to the checkpoint data directory.
        asynchronousSnapshots - This parameter is only there for API compatibility. Checkpoints are always asynchronous now.

      • FsStateBackend

        public FsStateBackend​(URI checkpointDataUri,
                      int fileStateSizeThreshold)
        Deprecated.
        Creates a new state backend that stores its checkpoint data in the file system and location defined by the given URI.

        A file system for the file system scheme in the URI (e.g., 'file://', 'hdfs://', or 'S3://') must be accessible via FileSystem.get(URI).

        For a state backend targeting HDFS, this means that the URI must either specify the authority (host and port), or that the Hadoop configuration that describes that information must be in the classpath.

        Parameters:
        checkpointDataUri - The URI describing the filesystem (scheme and optionally authority), and the path to the checkpoint data directory.
        fileStateSizeThreshold - State up to this size will be stored as part of the metadata, rather than in files

      • FsStateBackend

        public FsStateBackend​(URI checkpointDataUri,
                      int fileStateSizeThreshold,
                      boolean asynchronousSnapshots)
        Deprecated.
        Creates a new state backend that stores its checkpoint data in the file system and location defined by the given URI.

        A file system for the file system scheme in the URI (e.g., 'file://', 'hdfs://', or 'S3://') must be accessible via FileSystem.get(URI).

        For a state backend targeting HDFS, this means that the URI must either specify the authority (host and port), or that the Hadoop configuration that describes that information must be in the classpath.

        Parameters:
        checkpointDataUri - The URI describing the filesystem (scheme and optionally authority), and the path to the checkpoint data directory.
        fileStateSizeThreshold - State up to this size will be stored as part of the metadata, rather than in files (-1 for default value).
        asynchronousSnapshots - This parameter is only there for API compatibility. Checkpoints are always asynchronous now.

      • FsStateBackend

        public FsStateBackend​(URI checkpointDirectory,
                      @Nullable
                      URI defaultSavepointDirectory,
                      int fileStateSizeThreshold,
                      int writeBufferSize,
                      org.apache.flink.util.TernaryBoolean asynchronousSnapshots)
        Deprecated.
        Creates a new state backend that stores its checkpoint data in the file system and location defined by the given URI.

        A file system for the file system scheme in the URI (e.g., 'file://', 'hdfs://', or 'S3://') must be accessible via FileSystem.get(URI).

        For a state backend targeting HDFS, this means that the URI must either specify the authority (host and port), or that the Hadoop configuration that describes that information must be in the classpath.

        Parameters:
        checkpointDirectory - The path to write checkpoint metadata to.
        defaultSavepointDirectory - The path to write savepoints to. If null, the value from the runtime configuration will be used, or savepoint target locations need to be passed when triggering a savepoint.
        fileStateSizeThreshold - State below this size will be stored as part of the metadata, rather than in files. If -1, the value configured in the runtime configuration will be used, or the default value (1KB) if nothing is configured.
        writeBufferSize - Write buffer size used to serialize state. If -1, the value configured in the runtime configuration will be used, or the default value (4KB) if nothing is configured.
        asynchronousSnapshots - This parameter is only there for API compatibility. Checkpoints are always asynchronous now.

    • Method Detail

      • getBasePath

        @Deprecated
public org.apache.flink.core.fs.Path getBasePath()
        Deprecated.
        Deprecated in favor of getCheckpointPath().
        Gets the base directory where all the checkpoints are stored. The job-specific checkpoint directory is created inside this directory.
        Returns:
        The base directory for checkpoints.

      • getCheckpointPath

        @Nonnull
public org.apache.flink.core.fs.Path getCheckpointPath()
        Deprecated.
        Gets the base directory where all the checkpoints are stored. The job-specific checkpoint directory is created inside this directory.
        Overrides:
        getCheckpointPath in class AbstractFileStateBackend
        Returns:
        The base directory for checkpoints.

      • getMinFileSizeThreshold

        public int getMinFileSizeThreshold()
        Deprecated.
        Gets the threshold below which state is stored as part of the metadata, rather than in files. This threshold ensures that the backend does not create a large amount of very small files, where potentially the file pointers are larger than the state itself.

        If not explicitly configured, this is the default value of CheckpointingOptions.FS_SMALL_FILE_THRESHOLD.

        Returns:
        The file size threshold, in bytes.

      • getWriteBufferSize

        public int getWriteBufferSize()
        Deprecated.
        Gets the write buffer size for created checkpoint stream.

        If not explicitly configured, this is the default value of CheckpointingOptions.FS_WRITE_BUFFER_SIZE.

        Returns:
        The write buffer size, in bytes.

      • isUsingAsynchronousSnapshots

        public boolean isUsingAsynchronousSnapshots()
        Deprecated.
        Gets whether the key/value data structures are asynchronously snapshotted, which is always true for this state backend.

      • supportsSavepointFormat

        public boolean supportsSavepointFormat​(org.apache.flink.core.execution.SavepointFormatType formatType)
        Deprecated.
        Specified by:
        supportsSavepointFormat in interface StateBackend

      • configure

        public FsStateBackend configure​(org.apache.flink.configuration.ReadableConfig config,
                                ClassLoader classLoader)
        Deprecated.
        Creates a copy of this state backend that uses the values defined in the configuration for fields where that were not specified in this state backend.
        Specified by:
        configure in interface ConfigurableStateBackend
        Parameters:
        config - the configuration
        classLoader - The class loader that should be used to load the state backend.
        Returns:
        The re-configured variant of the state backend

      • createCheckpointStorage

        public CheckpointStorageAccess createCheckpointStorage​(org.apache.flink.api.common.JobID jobId)
                                                throws IOException
        Deprecated.
        Description copied from interface: CheckpointStorage
        Creates a storage for checkpoints for the given job. The checkpoint storage is used to write checkpoint data and metadata.
        Specified by:
        createCheckpointStorage in interface CheckpointStorage
        Parameters:
        jobId - The job to store checkpoint data for.
        Returns:
        A checkpoint storage for the given job.
        Throws:
        IOException - Thrown if the checkpoint storage cannot be initialized.

      • createKeyedStateBackend

        public <K> AbstractKeyedStateBackend<K> createKeyedStateBackend​(Environment env,
                                                                org.apache.flink.api.common.JobID jobID,
                                                                String operatorIdentifier,
                                                                org.apache.flink.api.common.typeutils.TypeSerializer<K> keySerializer,
                                                                int numberOfKeyGroups,
                                                                KeyGroupRange keyGroupRange,
                                                                TaskKvStateRegistry kvStateRegistry,
                                                                TtlTimeProvider ttlTimeProvider,
                                                                org.apache.flink.metrics.MetricGroup metricGroup,
                                                                @Nonnull
                                                                Collection<KeyedStateHandle> stateHandles,
                                                                org.apache.flink.core.fs.CloseableRegistry cancelStreamRegistry)
                                                         throws BackendBuildingException
        Deprecated.
        Description copied from interface: StateBackend
        Creates a new CheckpointableKeyedStateBackend that is responsible for holding keyed state and checkpointing it.

        Keyed State is state where each value is bound to a key.

        Specified by:
        createKeyedStateBackend in interface StateBackend
        Specified by:
        createKeyedStateBackend in class AbstractStateBackend
        Type Parameters:
        K - The type of the keys by which the state is organized.
        Parameters:
        env - The environment of the task.
        jobID - The ID of the job that the task belongs to.
        operatorIdentifier - The identifier text of the operator.
        keySerializer - The key-serializer for the operator.
        numberOfKeyGroups - The number of key-groups aka max parallelism.
        keyGroupRange - Range of key-groups for which the to-be-created backend is responsible.
        kvStateRegistry - KvStateRegistry helper for this task.
        ttlTimeProvider - Provider for TTL logic to judge about state expiration.
        metricGroup - The parent metric group for all state backend metrics.
        stateHandles - The state handles for restore.
        cancelStreamRegistry - The registry to which created closeable objects will be registered during restore.
        Returns:
        The Keyed State Backend for the given job, operator, and key group range.
        Throws:
        BackendBuildingException