Running things in the background

Path: Development > Programming in the AL language > Running things in the background · tier official · system development · narrative reviewed (checked by Opus)

Overview

This section covers the ways AL code can run work outside the user’s foreground session. Three mechanisms are described: the job queue, which lets end users schedule background jobs with recurring options; page background tasks, which run read-only computations for a page without blocking the user; and the task scheduler, which runs codeunits and reports at a specific date and time in a background session.

Start with the Async processing overview, which sets out the operational limits for background sessions, child sessions and scheduled tasks in online and on-premises environments. Then pick the page that matches your scenario: Job queue for user-scheduled and recurring jobs, Page Background Tasks for page responsiveness, and Task scheduler for programmatic scheduling with retry and failure handling. A subtopic holds the AL language reference pages (3 pages) for the related methods and types.

Key points

• The Async processing overview documents operational limits for background sessions, child sessions and scheduled tasks, online and on-premises.
• Job queue gives end users a way to schedule background jobs with recurring options. The page covers the job queue flow, dispatcher codeunit, error handler, parameter passing and permissions.
• Page Background Tasks run read-only computations or long processes asynchronously so pages stay responsive.
• Page background tasks use parent and child sessions, and take input through dictionary parameters.
• Page background tasks support timeout configuration, error levels (Ignore, Warning, Error), re-enqueuing and conditional cancellation.
• Task scheduler runs codeunits and reports at a set date and time in a background session.
• Task scheduler methods include CreateTask, SetTaskReady, TaskExists and CancelTask.
• Task scheduler handles retriable exceptions for transient errors and uses failure codeunits when a task fails.

Subtopics

• AL language reference (background processing) (3 pages)

More Learn pages

• Async processing Overview: Overview on the different ways an AL developer can do asynchronous (async) processing.
• Job queue: Learn about how the job queue works
• Page Background Tasks: Explains how to create page background tasks in Business Central.
• Task scheduler: Learn about scheduled tasks and how the task scheduler works.

Videos, posts and code changes

Linked by a Haiku matcher with a grounding quote from the item’s summary (link/topics.ts); machine-generated.

• #11257 Fix duplicate retention continuations for Waiting jobs (code change): “Fix duplicate retention continuations for Waiting jobs”
• #11262 Fix retention policy deletion-limit stop propagation (code change): “Fix retention policy deletion-limit stop propagation”
• #11890 Adding an in-product email storage cleanup (code change): “Scheduler proactively sends admins remediation steps”
• #11950 Adding an in-product email storage cleanup (backport to releases/29.x) (code change): “Adds codeunits for cleanup, a runner, a scheduler and inbox row deletion”
• #12117 [Job Queue] Clearer message and attempt number for runs interrupted by the platform (code change): “platform interrupts a job queue run, the log entry message now says”
• #9820 Use ReadCommitted isolation for CalcFields in Job Queue Entry GetXmlContent (code change): “Job Queue Entry GetXmlContent method now uses ReadCommitted isolation when reading”
• #148 Add Job Queue reliability and scheduling guidance (code change): “Require external side effects in Job Queue handlers to be idempotent”
• Background Page Tasks in Business Central Explained (community post): “Background page tasks enable pages to automatically refresh themselves”
• Dynamics 365 Business Central: the mistery around the “Parallel Session Management” codeunit. (community post): “Codeunit 490 is a manual, in-memory orchestrator using scope OnPrem procedures without async/await or platform-managed queues”
• If You Can’t Make It Fast, Make It Feel Fast (community post): “moving blocking work to the background instead of waiting for user input”
• 20260223 - If You Can’t Make It Fast, Make It Feel Fast (video): “background processing; job queue; page background task; task scheduler”

Source: Microsoft Learn (CC BY 4.0). Descriptions are Learn’s own.