openclaw - 💡(How to fix) Fix [Bug]: pdf-tool initialization blocks event loop for ~10s on every run [1 comments, 2 participants]

Bug type

Behavior bug (incorrect output/state without crash)

Beta release blocker

No

Summary

The pdf-tool core embedded tool takes ~10 seconds to initialize on every agent run, blocking the Node.js event loop completely. This causes session timeouts, queue stalls (65s+), and liveness warnings. Observed 35+ times consecutively.

Steps to reproduce

复现步骤：

Start OpenClaw 2026.5.2 on Windows 11 (npm global install) Send any message to trigger an agent run Check gateway logs for [trace:embedded-run] core-plugin-tool stages Observe openclaw-tools:pdf-tool consistently takes 9500–11500ms During this window, event loop utilization = 100%, all WS requests blocked

Expected behavior

Tool initialization should either (a) be lazy — only load when pdf tool is actually called, (b) cache after first load so subsequent runs don't re-initialize, or (c) run off the main thread.

Actual behavior

Every agent run re-initializes pdf-tool synchronously on the main thread (~10s). This blocks all other operations, causing:

liveness warning: eventLoopDelayMaxMs=11853.1, eventLoopUtilization=1 lane wait exceeded: waitedMs=65777 failover decision: surface_error reason=timeout from=xiaomi-coding/mimo-v2.5-pro

OpenClaw version

2026.5.2

Operating system

Windows 11 (10.0.22631 x64)

Install method

NPM Global

Model

xiaomi-coding/mimo-v2.5-pro

Provider / routing chain

OpenClaw -> token-plan-cn.xiaomimimo.com

Additional provider/model setup details

No response

Logs, screenshots, and evidence

# Trace (repeated 35+ times, all ~10s):
openclaw-tools:pdf-tool:10198ms@12216ms
openclaw-tools:pdf-tool:10584ms@12672ms
openclaw-tools:pdf-tool:9920ms@11304ms

# Liveness warning:
eventLoopDelayMaxMs=11853.1, eventLoopUtilization=1, cpuCoreRatio=0.763

# Queue stall:
lane=session:agent:main:main waitedMs=65777

# Session timeout:
failover decision: surface_error reason=timeout from=xiaomi-coding/mimo-v2.5-pro

Impact and severity

受影响：所有 agent 实例的每次对话 严重程度：高（每次对话 +10s 启动延迟，并发会话互相阻塞） 频率：100%（35+ 次连续观察） 后果：会话超时、队列 65s 等待、模型请求被误判超时

Additional information

pdf-tool 是 core embedded tool，不是 plugin，无法通过 plugins.entries 禁用 workaround：在 config 中设置 tools.deny: ["pdf"] 完全排除 建议修复：lazy loading / 初始化后 cache / 异步加载不阻塞主线程