Render loop causes memory explosion and session hang (yoga layout engine)

debug-log-render-loop.txt.gz

Render loop causes memory explosion and session hang (yoga layout engine)

Environment

• Claude Code version: 2.1.20
• OS: RHEL 9 (Linux 5.14.0-570.58.1.el9_6.x86_64)
• Platform: CLI

Description

Claude Code sessions hang and become unresponsive after running for a few minutes. The process consumes 13-19GB of memory and 60-80% CPU before becoming completely unresponsive.

Root Cause Analysis

Debug logs show the yoga layout engine entering a render loop, generating over 1 million re-render calls in ~15 minutes:

grep -c "Layout engine: yoga" debug-file.txt
1116136

The debug log files grow to 50-300MB due to continuous logging of:

• [DEBUG] Layout engine: yoga (1+ million times)
• [DEBUG] [ToolSearch:optimistic] mode=tst-auto, ENABLE_TOOL_SEARCH=undefined, result=true (thousands of times)

Reproduction

1. Start a new Claude Code session
2. Use the Task tool to spawn a subagent (e.g., jira-workflow)
3. Session hangs within minutes

Interesting finding: An established/running session can spawn subagents without hanging. Only new sessions exhibit this behavior consistently.

Evidence from debug logs

Session start (normal):

2026-01-27T22:16:20.499Z [DEBUG] Failed to check enabledPlatforms: TypeError: undefined is not an object (evaluating 'd7.join')
2026-01-27T22:16:20.652Z [DEBUG] [init] configureGlobalAgents starting
2026-01-27T22:16:20.652Z [DEBUG] [init] configureGlobalAgents complete

Then continuous render loop (problematic):

2026-01-27T22:27:09.717Z [DEBUG] Layout engine: yoga
2026-01-27T22:27:09.717Z [DEBUG] Layout engine: yoga
2026-01-27T22:27:09.717Z [DEBUG] Layout engine: yoga
... (millions of times)

Process state when hung

ps aux | grep claude
root     1024325 58.5 54.2 86528256 13184556 pts/0 Rl+ 14:40  38:58 claude

• 58% CPU
• 54% memory (13GB on 24GB system)
• Process must be killed with kill -9

Files available

Debug logs archived at: ~/.claude/debug-archive-2026-01-27/ (829MB total)

Largest files showing the issue:

• 17fbaea2-6696-4e52-8677-f7a5630ee02f.txt (323MB)
• 5aad5024-b094-4637-84ee-fa126ad4d0cb.txt (186MB)
• 082725b2-657b-42b3-8a19-5d74ae9d90cc.txt (58MB)

Workaround

The only workaround found is to use an already-running stable session rather than starting new sessions. Cleaning up debug logs before starting may also help.

Additional notes

• The enabledPlatforms TypeError appears in ALL sessions but doesn't seem to be the direct cause
• The render loop appears to be triggered during UI state updates related to tool search or task display
• MCP tools (Jira) work fine once the session is stable