openclaw - 💡(How to fix) Fix [Bug]: Gateway pegs a CPU core during agent tool run with no read I/O [2 pull requests]

Bug type

Behavior bug (incorrect output/state without crash)

Beta release blocker

No

Summary

During an embedded agent tool run, the gateway process can spend most samples at or above one full CPU core with no read I/O, indicating CPU-bound event handling rather than disk reads.

Steps to reproduce

1. Run a gateway with the Control UI connected during an embedded agent/tool run.
2. Capture pidstat -h -u -r -d -p <gateway-pid> 1 60 for the gateway process during the tool window.
3. Correlate the sample with gateway tool start/end logs and websocket event delivery.

Expected behavior

Gateway event handling should avoid redundant live tool-event projection and should preserve event-loop budget for timers, websocket control traffic, channel health checks, and chat latency.

Actual behavior

A 60-second sample averaged 83.66% CPU, had 42 of 60 rows at or above 100% CPU, peaked at 190% CPU, and averaged 0.00 kB/s read I/O. Gateway logs show the hot window overlapped an embedded tool run.

OpenClaw version

NOT_ENOUGH_INFO

Operating system

NOT_ENOUGH_INFO

Install method

NOT_ENOUGH_INFO

Model

NOT_ENOUGH_INFO

Provider / routing chain

NOT_ENOUGH_INFO

Additional provider/model setup details

NOT_ENOUGH_INFO

Logs, screenshots, and evidence

pidstat summary: rows=60 avg_usr=79.42 avg_sys=4.25 avg_wait=0.03 avg_cpu=83.66 avg_minflt=307.77 avg_majflt=0.00 avg_rd=0.00 avg_wr=90.16 avg_ccwr=67.10
cpu_ge_90_count=43 cpu_ge_100_count=42 max_cpu=190.0
selected rows:
05:07:11 cpu=100.00 rd=0.00 majflt=0 openclaw
05:07:47 cpu=190.00 rd=0.00 majflt=0 openclaw
05:08:04 cpu=101.00 rd=0.00 majflt=0 openclaw
redacted gateway correlation:
2026-05-21T05:07:47.187+00:00 agent/embedded embedded run tool start: runId=[redacted run id] tool=exec toolCallId=REDACTED
2026-05-21T05:08:04.330+00:00 agent/embedded embedded run tool end: runId=[redacted run id] tool=exec toolCallId=REDACTED

Impact and severity

Affected: gateways running embedded agent/tool work with live UI subscribers. Severity: high for responsiveness. Frequency: one exact 60-second live sample captured during the investigation. Consequence: one gateway process can consume a full core during tool-event handling, leaving less event-loop budget for other gateway responsibilities.

Additional information

Primary fix path: deduplicate live tool event mirrors so overlapping run-scoped and session-scoped websocket subscriptions do not receive duplicate tool frames. Related fix path: back off low-priority session tool mirrors while diagnostic queue pressure is active.