Analyzing Task Scheduler Telemetry

INTRODUCED IN: Business Central 2021 release wave 2

Task scheduler telemetry gathers information about the execution of scheduled tasks. The data gives insight into what happens in background sessions that are coming from scheduled tasks. It provides information that lets you troubleshoot failures. The data can also help you determine whether tasks would be better scheduled for off hours to limit the load on the service.

For an overview of task scheduler and to understand the flow related to task execution, see Task Scheduler.

Each scheduled task is assigned a unique identifier (ID), which is included in each trace related to the task. Using the ID makes it easy to query the flow of a task.

Task created

Occurs when a task was created by a TaskScheduler.CreateTask method call in AL code.

General dimensions

The following table explains the general dimensions of this trace.

Custom dimensions

Common custom dimensions

The following table explains other custom dimensions that are common to all task scheduler traces.

Task ready

Occurs when a task is set to the ready state by TaskScheduler.SetTaskReady method call in AL code. A task can't be run until it's in the ready state.

General dimensions

The following table explains the general dimensions of this trace.

Custom dimensions

Task removed

Occurs when a task is deleted by a TaskScheduler.CancelTask method call in AL code.

General dimensions

The following table explains the general dimensions of this trace.

Custom dimensions

Task canceled

Occurs when the execution of a task's main or failure codeunit is canceled by the service or by a user.

For example, the service cancels a task when:

• It takes longer to complete than the specified timeout. The timeout is specified on the task when it's created. Or if no timeout is specified, then the default timeout of the service is used. For online, the default task timeout is 12 hours. For on-premises, the default timeout is specified by the Default Task Scheduler Session Timeout setting on the Business Central Server instance.
• The Session.StopSession method was called from AL code.

Users can cancel a task a couple ways. For example, with Business Central online, they can use the Business Central admin center. With on-premises, they can run the Remove-NAVSession cmdlet.

General dimensions

The following table explains the general dimensions of this trace.

Custom dimensions

Task failed

Occurs when the execution of task's main codeunit or failure codeunit fails because of an exception thrown by the AL runtime.

General dimensions

The following table explains the general dimensions of this trace.

Custom dimensions

Analyzing report generation failures

When a task fails, the failureReason column in the CustomDimensions will include the name of the exception that was thrown by the AL runtime.

Sample KQL code (failed tasks)

This KQL code can help you get started analyzing task failures:

// Task failed
traces
| where timestamp > ago(60d) // adjust as needed
| where customDimensions has 'LC0045' // for performance 
| where customDimensions.eventId == 'LC0045'
| project timestamp
// in which environment/company did it happen
, aadTenantId = customDimensions.aadTenantId
, environmentName = customDimensions.environmentName
, environmentType = customDimensions.environmentType
, companyName = customDimensions.companyName
// what codeunit to run
, codeunitObjectId = customDimensions.codeunitObjectId
, failureCodeunitObjectId = customDimensions.failureCodeunitObjectId
// task info
, formatId = customDimensions.formatId
, isReady = customDimensions.isReady
, languageId = customDimensions.languageId
, notBefore = customDimensions.notBefore
, taskId = customDimensions.taskId
, timeout = customDimensions.timeout
// execution info
, failureReason = customDimensions.failureReason // this contains the name of the exception thrown by the AL runtime

Task completed

Occurs when the execution of a task's main codeunit or failure codeunit succeeds with no errors.

There's no event emitted for task started. You can infer the task-start time by subtracting the totalTime from the task completed timestamp.

General dimensions

The following table explains the general dimensions of this trace.

Custom dimensions

Task timeout changed because it was exceeding the max timeout value

INTRODUCED IN: Version 22.0

Occurs if the timeout defined on a task exceeds that maximum timeout allowed by the server. The task is then assigned the timeout that's equal to the maximum timeout allowed by the server.

General dimensions

The following table explains the general dimensions of this trace.

Custom dimensions

Task scheduler and performance

Scheduled tasks or job queue entries that are set to run on a recurring schedule can impact the performance of Business Central under either of the following conditions:

• They run too frequently.

  Consider how often the task or job needs to run. Especially for polling scenarios, you might have better and more performant ways to react, such as using webhooks.

• They run heavy jobs while many users are also using Business Central.

  Consider running them outside working hours. This might decrease locking and deadlock issues both for users and for the task or job itself.

See also

Task Scheduler
Telemetry overview
Enabling Telemetry
Alert on Telemetry