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Aljoscha Krettek updated FLINK-5763: ------------------------------------ Fix Version/s: (was: 1.5.0) 1.6.0 > Make savepoints self-contained and relocatable > ---------------------------------------------- > > Key: FLINK-5763 > URL: https://issues.apache.org/jira/browse/FLINK-5763 > Project: Flink > Issue Type: Improvement > Components: State Backends, Checkpointing > Reporter: Ufuk Celebi > Priority: Blocker > Fix For: 1.6.0 > > > After a user has triggered a savepoint, a single savepoint file will be > returned as a handle to the savepoint. A savepoint to {{<target>}} creates a > savepoint file like {{<target>/savepoint-<randomSuffix>}}. > This file contains the metadata of the corresponding checkpoint, but not the > actual program state. While this works well for short term management > (pause-and-resume a job), it makes it hard to manage savepoints over longer > periods of time. > h4. Problems > h5. Scattered Checkpoint Files > For file system based checkpoints (FsStateBackend, RocksDBStateBackend) this > results in the savepoint referencing files from the checkpoint directory > (usually different than <target>). For users, it is virtually impossible to > tell which checkpoint files belong to a savepoint and which are lingering > around. This can easily lead to accidentally invalidating a savepoint by > deleting checkpoint files. > h5. Savepoints Not Relocatable > Even if a user is able to figure out which checkpoint files belong to a > savepoint, moving these files will invalidate the savepoint as well, because > the metadata file references absolute file paths. > h5. Forced to Use CLI for Disposal > Because of the scattered files, the user is in practice forced to use Flink’s > CLI to dispose a savepoint. This should be possible to handle in the scope of > the user’s environment via a file system delete operation. > h4. Proposal > In order to solve the described problems, savepoints should contain all their > state, both metadata and program state, inside a single directory. > Furthermore the metadata must only hold relative references to the checkpoint > files. This makes it obvious which files make up the state of a savepoint and > it is possible to move savepoints around by moving the savepoint directory. > h5. Desired File Layout > Triggering a savepoint to {{<target>}} creates a directory as follows: > {code} > <target>/savepoint-<jobId>-<randomSuffix> > +-- _metadata > +-- data-<randomSuffix> [1 or more] > {code} > We include the JobID in the savepoint directory name in order to give some > hints about which job a savepoint belongs to. > h5. CLI > - Trigger: When triggering a savepoint to {{<target>}} the savepoint > directory will be returned as the handle to the savepoint. > - Restore: Users can restore by pointing to the directory or the _metadata > file. The data files should be required to be in the same directory as the > _metadata file. > - Dispose: The disposal command should be deprecated and eventually removed. > While deprecated, disposal can happen by specifying the directory or the > _metadata file (same as restore). -- This message was sent by Atlassian JIRA (v7.6.3#76005)