Claude Code CLI: Orphaned processes cause unbounded memory growth (10GB+ on macOS)

Summary

Claude Code CLI processes launched with --resume in interactive terminal mode become orphaned when their parent shell exits. These orphaned processes continue running indefinitely with PPID=1 (adopted by launchd), accumulating memory without bound. One process reached 10.24 GB of memory on a 16GB M4 MacBook Air, causing significant system heat and performance degradation.

Environment

• OS: macOS 15 (Darwin 25.2.0)
• Hardware: Apple M4 Air, 16GB RAM
• Claude Code Version: 2.1.15
• Claude Desktop App: 1.1.886
• Shell: zsh
• Terminal: macOS Terminal.app

Steps to Reproduce

1. Open a terminal and start Claude Code:

``bash
claude --model claude-opus-4-5-20251101
``

1. Use the session, note the session ID.
2. Open additional terminal tabs and resume the same session:

``bash
claude --resume <session-id> --model claude-opus-4-5-20251101
``

1. Close the terminal windows/tabs (Cmd+W or close Terminal app) without explicitly exiting the claude process (Ctrl+C or /exit).
2. Observe that the claude processes continue running as orphans.

Observed Behavior

Three orphaned Claude Code processes were found running, all resuming the same session:

| PID | PPID | RSS | Terminal | CPU Time |
|-----|------|-----|----------|----------|
| 16234 | 1 | ~3.0 GB (Activity Monitor: 10.24 GB) | s005 | 111 min |
| 47609 | 1 | ~390 MB | s007 | 29 min |
| 98485 | 1 | ~77 MB | s008 | 17 min |

All three had PPID=1 (launchd), confirming their parent shells had exited.

PID   %CPU %MEM    VSZ      RSS   TT  STAT  STARTED    TIME     COMMAND
16234 49.8 11.2 521416592 1886208 s005 Rs+  12:36AM 111:21.35 claude --resume 27033d6e-... --model claude-opus-4-5-20251101
47609  0.1  2.3 509698480  388688 s007 Rs+   9:39PM  29:18.43 claude --resume 27033d6e-... --model claude-opus-4-5-20251101
98485  0.0  0.5 510105968   76736 s008 Ss+  Mon09PM  17:39.44 claude --resume 27033d6e-... --model claude-opus-4-5-20251101

Key observations:

• PID 16234 was consuming 49.8% CPU continuously
• Memory was actively growing — RSS increased from 1.8 GB to 3.0 GB within minutes of observation
• The process had been running for ~23 hours
• Activity Monitor reported 10.24 GB for the largest process

Expected Behavior

When a parent terminal/shell exits, the Claude Code CLI process should:

1. Detect that stdin/the controlling terminal is gone (SIGHUP)
2. Gracefully shut down and release all resources
3. Not continue running as an orphan accumulating memory indefinitely

Root Cause Analysis

The Claude Code CLI (Node.js binary) does not properly handle:

1. SIGHUP signal — When the parent terminal closes, the shell sends SIGHUP to its child processes. The claude process either ignores SIGHUP or doesn't have a handler that triggers shutdown.

1. Detached stdin — When the controlling terminal is gone, stdin becomes invalid. The process should detect this and exit, but instead continues running.

1. Memory leak in long-running sessions — Even if orphaning were intended, the process exhibits unbounded memory growth (76 MB → 390 MB → 3+ GB over time), suggesting a memory leak in the Node.js runtime.

Impact

• Memory exhaustion: 10.24 GB consumed (64% of 16GB total RAM)
• CPU waste: 49.8% CPU consumed continuously with no purpose
• Thermal throttling: MacBook Air M4 noticeably hot
• Silent failure: No user-visible indication; only discoverable via Activity Monitor or ps

Workaround

# Find orphaned claude processes
ps -eo pid,ppid,rss,command | grep "claude" | awk '$2 == 1' | grep -v "Claude.app"

# Kill them
kill <PID>