[BUG] Memory leak in long-running idle Claude Code sessions

[diangao]

Preflight Checklist

• I have searched existing issues and this hasn't been reported yet
• This is a single bug report (please file separate reports for different bugs)
• I am using the latest version of Claude Code

What's Wrong?

Multiple idle Claude Code sessions accumulated ~15GB memory each over an 18-hour period without any user interaction. 4 sessions combined used ~60GB, exceeding my 24GB RAM and triggering macOS jetsam (OOM killer), causing a complete system crash.

Key finding: Debug logs show context size remained constant at 6664 chars throughout the 18 hours, yet each process grew to ~15GB. This suggests the leak is NOT from context accumulation but from something else (V8 heap fragmentation, MCP connections, internal caching, etc.).

From jetsam report:

• "largestProcess" : "2.1.7" (Claude Code)
• 4 processes with rpages 950,000-980,000 (~15GB each)
• Combined CPU time suggests processes were actively doing something despite being idle

What Should Happen?

Idle Claude Code sessions should:

• Maintain a low memory footprint (<500MB when idle)
• Release unused memory through garbage collection
• Not grow unboundedly without active user interaction

Error Messages/Logs

From /Library/Logs/DiagnosticReports/JetsamEvent-2026-01-15-182249.ips:

"largestProcess" : "2.1.7"

Process memory details (name: "2.1.7"):
PID 10652: rpages=977,907 (~15GB), cpuTime=1805.89s
PID 11129: rpages=950,678 (~14.5GB), cpuTime=3364.34s
PID 11605: rpages=981,949 (~15GB), cpuTime=391.86s
PID 75191: rpages=976,069 (~15GB), cpuTime=1604.92s

(macOS page size = 16KB, so 977,907 pages × 16KB ≈ 15GB)

From ~/.claude/debug/ logs - context stayed constant:
2026-01-15T00:30:45.055Z [DEBUG] Auto tool search disabled: 6664 chars
...
2026-01-16T02:14:31.824Z [DEBUG] Auto tool search disabled: 6664 chars

Steps to Reproduce

1. Run claude in terminal
2. Use the session normally (file reads, bash commands, etc.)
3. Stop interacting but keep the session open (don't /exit)
4. Monitor memory usage in Activity Monitor over time
5. Memory grows continuously even when idle

My specific case:

• 4 sessions open for ~18 hours
• Each grew to ~15GB despite being idle
• Context size stayed constant at 6664 chars (verified in debug logs)

The core issue: idle sessions accumulate memory without releasing it, regardless of context size.

Claude Model

Opus

Is this a regression?

Yes, this worked in a previous version

Last Working Version

No response

Claude Code Version

2.1.7 (at time of crash), now on 2.1.12

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

iTerm2

Additional Information

Environment:

• macOS 15.7 (24G207)
• Apple M2, 24GB RAM
• iTerm2 with zsh

Session timeline:

• Sessions started: 2026-01-15T00:01 UTC
• Crash time: 2026-01-15T18:22 PST
• Total runtime: ~18 hours
• User idle time before crash: ~2 hours

MCP configuration:

• claude-in-chrome MCP server was connected to some sessions

Available for debugging:

• Full jetsam report at /Library/Logs/DiagnosticReports/JetsamEvent-2026-01-15-182249.ips
• Debug logs in ~/.claude/debug/ from affected sessions
• Willing to provide additional logs or test fixes

[github-actions]

Found 3 possible duplicate issues:

1. [BUG] Memory allocation thrashing causes high sustained CPU usage when idle #18280
2. [BUG] Linux Native x64 build - unbounded memory leak even with clean session #12987
3. Memory leak causing V8 OOM crashes (SIGABRT) on extended sessions #18011

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

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🤖 Generated with Claude Code

[AojdevStudio]

Having a similar problem where it doesn't even start up, memory spikes!

[kylesnowschwartz]

Additional data point: macOS ARM64, MCP server memory accumulation

Experienced similar memory growth in a claude -c (continue) session.

Environment:

• Claude Code: 2.1.12
• macOS (Apple M3 Max, 36GB RAM)
• Terminal-based session

Observations:

Metric	Value
Session duration	~50 minutes
Claude process RSS	~3GB (started much lower)
CPU	Peaked at 101%, later dropped to 3.4%

MCP server memory accumulation:

Notably, the session's MCP servers also accumulated memory over time:

PID    RSS (MB)  Uptime   Process
37041  278MB     50min    mcp-server-playwright (old session)
53889  46MB      5min     mcp-server-playwright (fresh session)

The playwright MCP server from the long-running session grew to 6x the size of a freshly spawned one (278MB vs 46MB), suggesting MCP servers may be accumulating state without releasing it.

Process snapshot at ~50 min:

36698 2966160  7.9%  3.4%  50:37 claude -c
37041  278464  0.7%  0.1%  50:33 node mcp-server-playwright
37016   46432  0.1%  0.0%  50:33 node context7-mcp
36991   46416  0.1%  0.0%  50:33 node context7-mcp
36911   44720  0.1%  0.0%  50:34 node rollbar-mcp-server

This supports your hypothesis that the leak may involve MCP connections rather than context accumulation.

[alberduris]

Also seeing memory accumulation in idle sessions on v2.1.14 (macOS).