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.

**Table 1** Parameters
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: fixed-delay failure-rate none	none	No
restart-strategy.fixed-delay.attempts	Number of retry times when the fixed-delay restart strategy is used.	If the checkpoint is enabled, the default value is the value of Integer.MAX_VALUE. If the checkpoint is disabled, the default value is 3.	No
restart-strategy.fixed-delay.delay	Retry interval when the fixed-delay strategy is used. The unit is ms/s/m/h/d.	If the checkpoint is enabled, the default value is 10s. If the checkpoint is disabled, the default value is the value of akka.ask.timeout.	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