High CPU use in idle on macOS (Desktop & cli) #26416

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1. github-actions

   assigned

   rekram1-node

   on May 8, 2026
2. github-actions commented on May 8, 2026

   

   github-actionsBot

   on May 8, 2026 – with GitHub Actions

   Contributor

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   This issue might be a duplicate of existing issues. Please check:

   • High CPU usage in IDLE on Linux Kubuntu 25.10 #24393: High CPU usage in IDLE on Linux Kubuntu 25.10 (same idle CPU issue, different OS)
   • opencode is using CPU for doing nothing! #19466: opencode is using CPU for doing nothing! (same symptom - CPU use while idle)
   • High CPU usage on Desktop app while idle (WebView2) #18608: High CPU usage on Desktop app while idle (WebView2) (idle CPU on Desktop app)
   • [BUG]: OpenCode Desktop consumes lots of CPU cycles on Mac M4 & freezes completely while trying new WorkSpace feature #10257: [BUG]: OpenCode Desktop consumes lots of CPU cycles on Mac M4 & freezes completely (macOS Desktop CPU issue)
   • Fans being very loud when opening OpenCode, other apps are fine #17843: Fans being very loud when opening OpenCode, other apps are fine (likely same root cause)
3. Epicism commented on Jun 5, 2026

   

   Epicism

   on Jun 5, 2026

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   Also experiencing this issue.

   👍React with 👍4Reacted by Ömer Göktaş, Dmitrii Novikov, Ruben Rica and Gegham
4. viktor-ferenczi commented on Jun 26, 2026

   

   viktor-ferenczi

   on Jun 26, 2026

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   Same issue on Linux, suspect is rendering the damn progress indication with an embedded browser through a big DOM: #34045
5. Astro-Han commented on Jul 14, 2026

   

   Astro-Han

   on Jul 14, 2026

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   I saw a related macOS CLI problem on OpenCode 1.17.20, with one useful distinction: my reproducible case was tied to the busy spinner, not a true idle loop.

   With animations enabled, the active TUI used 24-43% CPU. Disabling animations dropped the same process to 1-13%, and toggling them back on restored the high usage. Once no busy indicator was visible, CPU settled near 1%. Details and source links: #30086 (comment)

   If CPU remains high after the session status is fully idle, that is probably another path. The animation toggle is still a useful discriminator for this issue.
6. sjursky commented on Aug 31, 2026

   

   sjursky

   on Aug 31, 2026

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   +1 on Linux (x86-64, Ubuntu 24.04.4 LTS), opencode v1.18.25. Reproduced the same idle high-CPU pattern.

   Symptom while the session is fully idle (no active request, no streaming, no file activity):

   • Main thread sits at ~50% of one core, STAT=Rl+ (running, not sleeping), WCHAN cycling through ep_poll.
   • The Bun HeapHelper thread sits at ~20-25% on futex — appears to be GC pressure driven by the main-loop churn.
   • No active network connections and no inotify event traffic at the time, so the spin is internal, not I/O-driven.

   This matches the epoll_pwait(..., timeout=0) busy-loop signature already reported in #24719 and #15600 — the runEventSubscription() reconnect loop in packages/opencode/src/acp/agent.ts with no backoff, and the broken-socket handling in http-server.ts / instance-events.ts. The main loop appears to poll with a zero timeout and immediately re-enters instead of blocking. The empty-string spin in MultiOccurrenceReplacer (packages/opencode/src/tool/edit.ts) is a related event-loop-blocking path.

   Killing and restarting the affected session is the only reliable workaround (consistent with #21889's findings). A proper fix would have the event loop block with a non-zero timeout / sleep when no events are pending, and add backoff to the reconnect path.

   Happy to provide more detail if useful. Would be great to know if a fix is planned for this, since it's been reported across several versions and platforms.
7. neriousy commented on Oct 1, 2026

   

   neriousy

   on Oct 1, 2026

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   Closing as a duplicate of #19466, which tracks OpenCode using CPU while idle. Please add your platform and version there.
8. neriousy

   closed this as a duplicateof opencode is using CPU for doing nothing! #19466 on Oct 1, 2026