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domain |
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technologies |
countries |
application-area |
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performance |
| event |
| subscriber |
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Keep event subscribers lightweight
Contributions welcome — open a PR to refine or extend this article.
Description
Event subscribers run synchronously on the publisher's thread. If a subscriber does heavy work — a database query, a web service call, a layout render — every caller of the publisher pays that cost. Subscribers on hot events (OnAfterValidate on common fields, OnBeforeInsert on ledger-entry-like tables) can multiply a small per-call cost into a system-wide regression.
Best Practice
Keep subscribers small: guard early with inexpensive checks, defer heavy work to a task queue or a background session, and cache results across invocations when the data is stable.
Anti Pattern
Calling an external web service, running a report, or iterating a large table from inside an event subscriber on a hot publisher makes every operation on that publisher as slow as the heaviest subscriber.
See sample: keep-event-subscribers-lightweight.bad.al.