mirror of
https://github.com/microsoft/BCQuality.git
synced 2026-10-05 14:46:55 +01:00
2b5550c346
Lead with a complete plugin quick start and add task-oriented usage, troubleshooting, customization, and contribution guides. Preserve the broader plugin framing, correct conflicting contract guidance, support Agents folder reviews, and align repository validation. Convert existing sample references to clickable links without changing knowledge rules. Co-authored-by: Jesper Schulz-Wedde <jesper.schulzwedde@microsoft.com> Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>
28 lines
1.7 KiB
Markdown
28 lines
1.7 KiB
Markdown
---
|
|
bc-version: [all]
|
|
domain: performance
|
|
keywords: [singleinstance, subscriber, event, memory, session]
|
|
technologies: [al]
|
|
countries: [w1]
|
|
application-area: [all]
|
|
---
|
|
|
|
# Avoid growing globals in SingleInstance subscribers
|
|
|
|
> Contributions welcome — open a PR to refine or extend this article.
|
|
|
|
## Description
|
|
|
|
A codeunit with `SingleInstance = true` is allocated once per session and lives until the session ends. Global variables on it are never collected between event fires. A subscriber that accumulates data into a global — buffering payloads, appending to a list, caching without a cap — steadily grows its session footprint for the entire user session. The symptom is memory that only recovers on sign-out, and it surfaces only on long-running sessions.
|
|
|
|
## Best Practice
|
|
|
|
Keep the global footprint on a SingleInstance subscriber bounded and intentional: a handful of flags, a setup record, a bounded cache with a maximum size. When cross-event state is genuinely needed, define an explicit reset point — end of a business process, arrival of a specific terminal event — that clears the growing collection.
|
|
|
|
See sample: [`avoid-growing-globals-in-singleinstance-subscribers.good.al`](avoid-growing-globals-in-singleinstance-subscribers.good.al).
|
|
|
|
## Anti Pattern
|
|
|
|
A SingleInstance subscriber that appends each event's payload to a global list, dictionary, or temporary record without a cap or cleanup trigger. The list grows for hours, memory pressure builds quietly, and debugging the root cause on a live environment is substantially harder than noticing the unbounded append in code review.
|
|
|
|
See sample: [`avoid-growing-globals-in-singleinstance-subscribers.bad.al`](avoid-growing-globals-in-singleinstance-subscribers.bad.al).
|