Edit

Task start event

  • Article

This event is emitted once a task has been scheduled to start on a compute node by the scheduler. Note that if the task is retried or requeued this event will be emitted again for the same task, but the retry count and system task version will be updated accordingly.

The following example shows the body of a task start event.

{
    "jobId": "myJob",
    "id": "myTask",
    "taskType": "User",
    "systemTaskVersion": 220192842,
    "requiredSlots": 1,
    "nodeInfo": {
        "poolId": "pool-001",
        "nodeId": "tvm-257509324_1-20160908t162728z"
    },
    "multiInstanceSettings": {
        "numberOfInstances": 1
    },
    "constraints": {
        "maxTaskRetryCount": 2
    },
    "executionInfo": {
        "retryCount": 0
    }
}
Element name Type Notes
jobId String The ID of the job containing the task.
id String The ID of the task.
taskType String The type of the task. This can either be 'JobManager' indicating it is a job manager task or 'User' indicating it is not a job manager task.
systemTaskVersion Int32 This is the internal retry counter on a task. Internally the Batch service can retry a task to account for transient issues. These issues can include internal scheduling errors or attempts to recover from compute nodes in a bad state.
requiredSlots Int32 The required slots to run the task.
nodeInfo Complex Type Contains information about the compute node on which the task ran.
multiInstanceSettings Complex Type Specifies that the task is Multi-Instance Task requiring multiple compute nodes. See multiInstanceSettings for details.
constraints Complex Type The execution constraints that apply to this task.
executionInfo Complex Type Contains information about the execution of the task.

nodeInfo

Element name Type Notes
poolId String The ID of the pool on which the task ran.
nodeId String The ID of the node on which the task ran.

multiInstanceSettings

Element name Type Notes
numberOfInstances Int The number of compute nodes required by the task.

constraints

Element name Type Notes
maxTaskRetryCount Int32 The maximum number of times the task may be retried. The Batch service retries a task if its exit code is nonzero.

Note that this value specifically controls the number of retries. The Batch service will try the task once, and may then retry up to this limit. For example, if the maximum retry count is 3, Batch tries a task up to 4 times (one initial try and 3 retries).

If the maximum retry count is 0, the Batch service does not retry tasks.

If the maximum retry count is -1, the Batch service retries tasks without limit.

The default value is 0 (no retries).

executionInfo

Element name Type Notes
retryCount Int32 The number of times the task has been retried by the Batch service. The task is retried if it exits with a nonzero exit code, up to the specified MaxTaskRetryCount