State Backend¶
Scenarios¶
Flink enables HA and job exception, as well as job pause and recovery during version upgrade. Flink depends on state backend to store job states and on the restart strategy to restart a job. You can configure state backend and the restart strategy.
Configuration Description¶
Configuration items include the state backend type, storage path, and restart strategy.
Parameter | Description | Default Value | Mandatory |
|---|---|---|---|
state.backend.fs.checkpointdir | Path when the backend is set to filesystem. The path must be accessible by JobManager. Only the local mode is supported. In the cluster mode, use an HDFS path. | hdfs:///flink/checkpoints | No |
state.savepoints.dir | Savepoint storage directory used by Flink to restore and update jobs. When a savepoint is triggered, the metadata of the savepoint is saved to this directory. | hdfs:///flink/savepoint | Mandatory in security mode |
restart-strategy | Default restart policy, which is used for jobs for which no restart policy is specified. The options are as follows:
| none | No |
restart-strategy.fixed-delay.attempts | Number of retry times when the fixed-delay restart strategy is used. |
| No |
restart-strategy.fixed-delay.delay | Retry interval when the fixed-delay strategy is used. The unit is ms/s/m/h/d. |
| No |
restart-strategy.failure-rate.max-failures-per-interval | Maximum number of restart times in a specified period before a job fails when the fault rate policy is used. | 1 | No |
restart-strategy.failure-rate.failure-rate-interval | Retry interval when the failure-rate strategy is used. The unit is ms/s/m/h/d. | 60 s | No |
restart-strategy.failure-rate.delay | Retry interval when the failure-rate strategy is used. The unit is ms/s/m/h/d. | The default value is the same as the value of akka.ask.timeout. For details, see Distributed Coordination (via Akka). | No |