docs: clarify configurable concurrency in overview by lilin90 · Pull Request #21977 · pingcap/docs-cn

lilin90 · 2026-10-13T09:45:17Z

What is changed, added, or deleted? (Required)

Clarify the concurrency wording in overview.md.

The overview previously said that each TiDB node supports a maximum of 1,000 concurrencies. However, 1,000 is the default value of token-limit, not the maximum. This PR updates the overview to say that each TiDB node supports 1,000 concurrent sessions by default and that you can configure this limit up to 1,048,576.

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What is the related PR or file link(s)?

Related code change PR links (if applicable):
This PR is translated from: docs: clarify configurable concurrency in overview docs#24207
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Summary by CodeRabbit

文档
- 明确默认每个 TiDB 节点最多允许 1,000 个会话并发执行请求；可通过 token-limit 将上限调至最高 1,048,576。计算节点上限仍为 512，集群容量仍为 PB 级别。
- 更新令牌等待条件：单个 TiDB 实例上的并发会话数达到 token-limit 时，后续请求需等待。

Copilot

Copilot wasn't able to review any files in this pull request. Check if the Files changed in this pull request are included in default exclusions.

Synced from: pingcap/docs#24207 Target PR: pingcap#21977 Co-authored-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>

github-actions · 2026-10-13T09:46:51Z

Auto-sync completed successfully

Source PR: pingcap/docs#24207
Target PR: #21977

Chinese documentation has been updated based on English documentation changes.

ti-chi-bot · 2026-10-13T09:47:00Z

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coderabbitai · 2026-10-13T09:47:20Z

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overview.md

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📝 Walkthrough

更新 OLTP 场景中的 TiDB 并发限制说明，并调整 get token 阶段的等待条件及配置链接。

Changes: 并发限制文档

Layer / File(s)	Summary
并发限制与 token 说明 `overview.md`, `performance-tuning-methods.md`	`overview.md` 说明每个 TiDB 节点默认允许 1,000 个会话并发执行请求，并可通过 `token-limit` 调高至 1,048,576。`performance-tuning-methods.md` 将等待条件改为单个 TiDB 实例的并发会话数达到 `token-limit`，并更新配置项链接。

Priority: ⬇️ Low

Estimated code review effort: 1 (Trivial) | ~4 minutes

Change: Other

Suggested reviewers: qiancai

Merge Risk: ⚪ Minimal · up to 69661

The updated guidance matches the documented token limit and waiting behavior; no actionable issue remains, and the documentation change is ready to merge.

### Architecture Summary

Architecture risk: 🔵 Low · up to 69661

The change affects 2 systems.

Changed systems: overview.md, performance-tuning-methods.md

Architecture concerns
No architecture-level concerns identified.

Review details

Systems and components

observed — overview.md (service) was modified; 1 changed file maps to changed impact.
observed — performance-tuning-methods.md (service) was modified; 1 changed file maps to changed impact.

Before / after behavior

observed — Modified behavior in performance-tuning-methods.md: get token 阶段的等待条件改为单个 TiDB 实例上的并发会话数达到 token-limit 后，后续请求等待可用 token；旧文案描述连接数触及限制时创建连接被限流，且链接未指向具体配置项锚点。
observed — Modified behavior in overview.md: OLTP 场景说明将“每个节点最大支持 1000 并发”改为默认每个 TiDB 节点最多允许 1,000 个会话并发执行请求，并说明可通过 token-limit 将限制最高调至 1,048,576。

Pre-merge checks: 5

Passed checks: 5 passed

Check name	Status	Explanation
Title check		标题简洁明确，准确概括了主要变更：澄清 overview.md 中可配置的并发限制。
Description check		描述已填写变更内容、适用版本、相关链接、AI agent 参与情况和变更类型检查项。内容与实际改动一致。首次贡献者清单可按模板说明省略。
Docstring Coverage		No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check. Docstring coverage is scoped to functions touched by this diff. Analyzed 0 functions across 0…
Linked Issues check		Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check		Check skipped because no linked issues were found for this pull request.

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Copilot

🟡 Changes recommended

The overview should explicitly identify 1,048,576 as the configurable upper limit.

1 open finding

未明确配置值的上限含义 · New

🧠 Review effort: Balanced

Updated the description of TiDB's capabilities in handling large data and high concurrency scenarios. Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>

ti-chi-bot · 2026-10-20T09:03:51Z

[LGTM Timeline notifier]

Timeline:

2026-10-20 09:03:50.987881585 +0000 UTC m=+94643.247968513: ☑️ agreed by GMHDBJD.

Create empty translation PR

db99149

Copilot AI balanced review requested due to automatic review settings October 13, 2026 09:45

Copilot AI reviewed Oct 13, 2026

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ti-chi-bot Bot added the size/XS Denotes a PR that changes 0-9 lines, ignoring generated files. label Oct 13, 2026

lilin90 self-assigned this Oct 13, 2026

Auto-sync: Update Chinese docs from English PR

ff17d70

Synced from: pingcap/docs#24207 Target PR: pingcap#21977 Co-authored-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>

lilin90 requested a balanced review from Copilot October 14, 2026 02:04

Copilot started reviewing on behalf of lilin90 October 14, 2026 02:05

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Comment thread overview.md Outdated

lilin90 requested a review from GMHDBJD October 14, 2026 02:10

Revise TiDB capacity and concurrency details

6966107

Updated the description of TiDB's capabilities in handling large data and high concurrency scenarios. Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>

GMHDBJD approved these changes Oct 20, 2026

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ti-chi-bot Bot added the needs-1-more-lgtm Indicates a PR needs 1 more LGTM. label Oct 20, 2026

lilin90 added the lgtm label Oct 21, 2026

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docs: clarify configurable concurrency in overview - #21977

docs: clarify configurable concurrency in overview#21977
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lilin90:docs/fix-overview-token-limit-24207

lilin90 commented Oct 13, 2026 •

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