Claude Code CLI triggers macOS kernel memory leak (kalloc.1024) → kernel panic

[stereome]

Summary

Claude Code CLI triggers a kernel-level memory leak in macOS kalloc.1024 zone at ~30-48 MB/min, exhausting 16 GB RAM and causing kernel panic (WindowServer watchdog timeout) within 4-6 hours of use. The leak occurs in any terminal emulator (iTerm2, Terminal.app) and stops immediately when Claude Code process is terminated.

Environment

• macOS: 15.7.5 (Sequoia), also reproduced on 15.7.4
• Hardware: MacBook Pro M1 Pro, 16 GB RAM
• Claude Code: 2.1.92 (also observed on earlier versions)
• Terminals tested: iTerm2 (Metal ON and OFF), Terminal.app
• Node: bundled with Claude Code

Reproduction

1. Reboot Mac (clean state, kalloc.1024 < 200 MB)
2. Launch Claude Code CLI in any terminal
3. Monitor kalloc.1024 zone: sudo zprint | awk '/data\.kalloc\.1024/ {print $3}'
4. Observe ~30-48 MB/min growth in kernel memory
5. After 4-6 hours: kalloc.1024 reaches 11-14 GB → WindowServer watchdog timeout → kernel panic

Evidence: Controlled Experiments (April 7, 2026)

Experiment 1: Claude Code ON vs OFF (definitive)

Conditions	kalloc.1024 Δ/min	Result
iTerm + Metal ON + Claude Code	~30 MB/min	Leaking
iTerm + Metal OFF + Claude Code	~36 MB/min	Metal is NOT the cause
Terminal.app + Claude Code	~42 MB/min	iTerm is NOT the cause
Terminal.app + Claude Code, all other apps closed	~44 MB/min	Other apps NOT the cause
Terminal minimized, Claude Code idle	~27 MB/min	Still leaking even idle
macOS Safe Mode + Claude Code	Leaking	kext NOT the cause
No terminal with Claude Code running	0 MB/min	CONFIRMED: Claude Code is the trigger

Experiment 2: 5-minute OFF/ON cycle (timestamped CSV log)

Claude Code running (22:18–22:42):

22:18  kalloc.1024 = 1675 MB
22:30  kalloc.1024 = 2144 MB  (+42 MB/min)
22:42  kalloc.1024 = 2646 MB  (+42 MB/min)

Claude Code killed (~22:43):

22:43  kalloc.1024 = 2660 MB  (inertia)
22:44  kalloc.1024 = 2660 MB  (0 MB/min) ← STOPPED
22:45  kalloc.1024 = 2660 MB  (0 MB/min)
22:46  kalloc.1024 = 2660 MB  (0 MB/min)
22:47  kalloc.1024 = 2660 MB  (0 MB/min)

4 consecutive minutes of zero growth after killing Claude Code.

Kernel panic logs

Two kernel panics with identical signature:

panic: userspace watchdog timeout: no successful checkins from WindowServer in 120 seconds
Zone info: data.kalloc.1024  11G  (April 5)
Zone info: data.kalloc.1024  13G  (April 7)

Full panic logs available at:

• /Library/Logs/DiagnosticReports/panic-full-2026-04-07-095644.0002.panic
• /Library/Logs/DiagnosticReports/panic-full-2026-04-05-101144.0002.panic

Hypothesis: Root Cause

Claude Code's Ink/React-based TUI generates a high-frequency stream of terminal redraws. Each redraw triggers kernel allocations through the GPU compositor pipeline:

Claude Code (Node/Ink) → terminal escape sequences → Terminal.app/iTerm 
→ WindowServer → AGXG13X (Apple GPU driver) → kalloc.1024 allocations

The allocations in kalloc.1024 are never freed — this is a kernel-side bug (likely in Apple's GPU driver or WindowServer), but Claude Code is the only known application that triggers it at this rate due to its TUI rendering pattern.

Related Issues

• #32752 — Native addon memory leak (~18 GB/hour), node-pty suspected
• Critical Memory Leak: Claude Code Consumed 129GB RAM and Caused System Freeze #11315 — 129 GB RAM consumed, system freeze
• [Memory Leak] Claude Code 2.1.19 consuming ~12GB RAM on macOS 15.5 #23252 — 12 GB on macOS 15.5
• [BUG] Memory leak + Swap growth — Claude Code Sonnet 4.6 kills sessions in ~8 min (v2.1.49) #27421 — Sessions killed in 8 min (v2.1.49)
• [Bug] Memory Leak in Claude Code CLI #33673 — Recent CLI memory leak
• ghostty-org/ghostty#10289 — Ghostty found and fixed their side of the terminal leak triggered by Claude Code's multi-codepoint output (fix in Ghostty 1.3)

Possible Mitigations

On Claude Code side:

• Reduce TUI redraw frequency (throttle Ink render cycles)
• Batch terminal escape sequence output
• Offer a "low-rendering" or "plain text" mode for long sessions
• Investigate if node-pty buffer handling contributes to kernel allocations

Workarounds (user side):

• Reboot every 3-4 hours when using Claude Code
• Use Claude Code via SSH to a remote machine
• Use claude.ai web interface instead of CLI
• Monitor kalloc.1024 and reboot when > 8 GB

Monitoring Script

CSV logger that tracks kalloc.1024 every 60 seconds (used for the data above):

# One-liner to check current kalloc.1024
sudo zprint | awk '/data\.kalloc\.1024/ {print $3}' | head -1

Full monitoring script and CSV data available on request.

[github-actions]

Found 3 possible duplicate issues:

1. Kernel panic: 3 Claude processes hit 17.3 GB resident on 18 GB machine, MacBook powered off (v2.1.37) #24960
2. [BUG] Claude Code VS Code extension causes kernel panics (watchdogd timeout/Jetsam OOM) on MacBook Pro M3 Pro with 18 GB RAM #39253
3. [BUG] Claude Desktop causes repeated WindowServer crashes on macOS 15.7.3 (Sequoia) — VirtualDisplayListener deadlock #40663

This issue will be automatically closed as a duplicate in 3 days.

• If your issue is a duplicate, please close it and 👍 the existing issue instead
• To prevent auto-closure, add a comment or 👎 this comment

🤖 Generated with Claude Code

[github-actions]

This issue has been automatically closed as a duplicate of #24960.

If this is incorrect, please re-open this issue or create a new one.

🤖 Generated with Claude Code

[github-actions]

This issue has been automatically locked since it was closed and has not had any activity for 7 days. If you're experiencing a similar issue, please file a new issue and reference this one if it's relevant.