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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>
26 lines
1.7 KiB
Markdown
26 lines
1.7 KiB
Markdown
---
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bc-version: [all]
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domain: performance
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keywords: [findset, updlock, readisolation, locking, modify, obsolete-syntax]
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technologies: [al]
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countries: [w1]
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application-area: [all]
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---
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# FindSet(true) applies UpdLock on the read; the two-parameter form is obsolete
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## Description
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`FindSet()` and `FindSet(false)` are read-only — no locking. Per the upstream guidance, `FindSet(true)` "signifies the intent is to modify records" and "sets `ReadIsolation::UpdLock` on the record before finding rows." That is exactly the right shape when the loop body modifies each row: the read takes the same lock the modification will need, avoiding the deadlock window between an unlocked read and a later upgrade. The older two-parameter form `FindSet(ForUpdate, UpdateKey)` is obsolete — only the single-parameter signature should appear in new code.
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## Best Practice
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Use `FindSet(true)` only when the loop body genuinely modifies the iterated rows; use `FindSet()` (or `FindSet(false)`) when the loop only reads. Do not write `FindSet(true, true)` or `FindSet(true, false)` — the two-parameter form is the obsolete signature.
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See sample: [`findset-true-applies-updlock-on-read.good.al`](findset-true-applies-updlock-on-read.good.al).
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## Anti Pattern
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`FindSet(true)` on a loop that does not modify the iterated rows takes an `UpdLock` the work does not need; competing readers and writers stall against a lock the loop never uses. The mirror anti-pattern is `FindSet()` (no parameter) on a loop that *does* modify each row — the read takes a shared lock, the `Modify` then needs to upgrade, and the gap between them is a deadlock candidate.
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See sample: [`findset-true-applies-updlock-on-read.bad.al`](findset-true-applies-updlock-on-read.bad.al).
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