Handle psutil.virtual_memory failures on macOS

[yuuki84573]

Summary

This PR prevents ComfyUI from crashing when psutil.virtual_memory() raises a RuntimeError.

On macOS 27 beta 2, psutil.virtual_memory() can fail with:

RuntimeError: host_statistics64(HOST_VM_INFO64) syscall failed: (ipc/mig) array not large enough

This was reported in #14498.
The crash happens during prompt execution when ComfyUI checks available system memory. This PR wraps ComfyUI's psutil.virtual_memory() usage and falls back to safe/default memory values when that call fails, allowing execution to continue instead of crashing the prompt worker thread.

Fixes #14498

Changes

• Added a small helper around psutil.virtual_memory().
• Replaced direct memory-stat calls in execution and memory-management paths.
• Logs a warning once when fallback memory values are used.
• Preserves existing behavior when psutil.virtual_memory() works normally.

Testing

• Reproduced the issue on macOS 27 beta 2.
• Verified ComfyUI no longer crashes during prompt execution.
• Confirmed the fallback path is used and logs:

psutil.virtual_memory() failed; using fallback memory values

• Ran Python syntax checks on the modified files.

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Reviewing files that changed from the base of the PR and between 67d6cca and 9f8f0da.

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• comfy/psutil_utils.py

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📓 Path-based instructions (3)

**/*.py

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**/*.py: Keep imports at module scope; avoid inline imports unless they are already part of an established optional-backend probe or are needed to avoid an import cycle.
Do not add unnecessary try/except blocks; use them only for optional dependency, platform, or backend capability detection when the program has a useful fallback, and prefer specific exception types when changing new code.
Remove workarounds for PyTorch versions that ComfyUI no longer officially supports; if a workaround does not have a comment naming the exact supported PyTorch version(s), remove it.
Let unsupported model formats, invalid quantization metadata, and bad states fail with clear errors instead of silently producing lower quality output.
Match the existing local style in the file you edit; this codebase tolerates long lines, simple helper functions, module-level state, and direct tensor operations when they make the code easier to follow.
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Treat dtype, device placement, VRAM usage, and offloading behavior as core correctness concerns; check CPU, CUDA, ROCm, MPS, DirectML, XPU, NPU, and low VRAM implications when touching shared execution or loading code.
Prefer native ComfyUI formats and existing quantization/offload helpers over adding parallel code paths; use comfy.quant_ops, comfy.model_management, comfy.memory_management, comfy.pinned_memory, comfy_aimdo, and comfy-kitchen helpers where they already solve the problem.
Use optimized comfy-kitchen ops where they improve performance without changing expected dtype, device, memory, or interface behavior.
All models should use the optimized attention function selected by ComfyUI; higher-level code must not inspect function identity, names, modules, or implementation details to decide behavior.
Apply the same opacity rule to similar patterns beyond...

Files:

• comfy/psutil_utils.py

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**: ## Engineering Style

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Files:

• comfy/psutil_utils.py

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Flag PR changes that violate AGENTS.md even when the code is otherwise functional.
In particular, enforce architecture boundaries, dtype/device/memory rules,
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Files:

• comfy/psutil_utils.py

comfy/**

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comfy/**: Core ML/diffusion engine. Focus on:

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Files:

• comfy/psutil_utils.py

🧠 Learnings (2)

📚 Learning: 2026-02-21T14:01:41.482Z

Learnt from: pythongosssss
Repo: Comfy-Org/ComfyUI PR: 12555
File: comfy_extras/nodes_glsl.py:719-724
Timestamp: 2026-02-21T14:01:41.482Z
Learning: In PyOpenGL, bare Python scalars can be accepted for 1-element array parameters by NumberHandler. This means you can pass an int/float directly to OpenGL texture deletion (e.g., glDeleteTextures(tex)) without wrapping in a list. Verify function-specific expectations and ensure types match what the OpenGL call expects; use explicit lists only when the API requires an array.

Applied to files:

• comfy/psutil_utils.py

📚 Learning: 2026-05-13T12:31:45.069Z

Learnt from: rattus128
Repo: Comfy-Org/ComfyUI PR: 13802
File: comfy/pinned_memory.py:19-30
Timestamp: 2026-05-13T12:31:45.069Z
Learning: When reviewing code that uses comfy/pinned_memory.py’s `HostBuffer.extend(size=..., reallocate=...)`: by default (`reallocate` is not True / False), `extend(size=...)` is a *relative increment* that grows the buffer by `size` bytes—so slicing like `[offset:offset+size]` after `hostbuf.extend(size=size)` is correct and the argument should not be rewritten to `offset + size`. Only in the single-segment reallocation mode (`reallocate=True`, e.g., as used by `resize_pin_buffer()` in `comfy/model_management.py`) should `size` be treated as an *absolute target* and the call/arguments should be checked accordingly.

Applied to files:

• comfy/psutil_utils.py

🔇 Additional comments (3)

comfy/psutil_utils.py (3)

13-19: LGTM!

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36-43: LGTM!

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21-33: 🗄️ Data Integrity & Integration

Fallback shape is sufficient here; the only in-repo callers use total and available.

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📝 Walkthrough

Walkthrough

Changes

A new comfy.psutil_utils module wraps psutil.virtual_memory() with a RuntimeError fallback and one-time warning. comfy/model_management.py, comfy_execution/caching.py, and execution.py now import that helper module instead of psutil directly, and their RAM total/available checks use the new helper functions.

Related Issues: None specified.

Related PRs: None specified.

Suggested labels: memory-management, refactor

Suggested reviewers: None specified

Poem: A fallback woke on memory’s shore,
and psutil calls were used no more.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title accurately summarizes the main change: handling psutil.virtual_memory failures on macOS.
Description check	✅ Passed	The description clearly matches the changeset and explains the crash fix, helper, and fallback behavior.
Linked Issues check	✅ Passed	The changes add fallback memory handling and replace direct psutil memory checks in the affected paths, addressing the linked crash.
Out of Scope Changes check	✅ Passed	The modified files all support the memory-failure fix and do not introduce unrelated changes.

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[yuuki84573]

I pushed the docstring fix. The required workflows are awaiting maintainer approval.