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torch.compile Memory

torch.compile can use additional memory for graph compilation, guard evaluation, and dynamic shape handling.

Quick answer

torch.

Symptom
torch.compile causes OOM
Root cause
torch.compile keeps compiled graphs in memory. Recompilation on dynamic shapes.
Recommended fix
Set torch._dynamo.config.cache_size_limit=64
How Denpex helps
Denpex investigates torch.compile Memory using the evidence you provide or your connected workload collects. Earlier rank, host or application evidence is needed to distinguish an initiating failure from a downstream report.
Memory#torch-compile#dynamo#compilation#memory#performance

What this failure is

torch.compile Memory is a Memory failure seen during ML training runs. torch.compile can use additional memory for graph compilation, guard evaluation, and dynamic shape handling. Common tags: Torch Compile, Dynamo, Compilation, Memory.

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Why it happens (the mechanism)

Torch.compile keeps compiled graphs in memory. Recompilation on dynamic shapes. Different configs for different model parts. Guard evaluation overhead. Taken together, these mechanisms explain why the failure is reproducible, why it tends to surface on specific workloads or scales, and why generic mitigation attempts often fall short without addressing the underlying cause.

What you'll observe

  • Memory grows with torch.compile
  • First iterations are slow
  • Memory is fragmented after compile

Common symptoms and what they mean

SymptomWhy it happens
torch.compile causes OOMtorch.compile keeps compiled graphs in memory
Memory higher with torch.compile than eager modeRecompilation on dynamic shapes
torch.compile recompiles on shape changeDifferent configs for different model parts

Which systems are affected

  • Training with torch.compile
  • Inference with torch.compile
  • Using dynamo for performance

How to confirm this is the problem

Use this checklist to test the hypothesis against a small reproduction. No single line proves the root cause, so preserve the preceding events and compare one variable at a time.

  • ✓Reproduce the failure from a clean checkpoint/seed: the symptom must appear without warm-up state from a previous run.
  • ✓Verified signal present: torch.compile causes OOM
  • ✓Verified signal present: Memory higher with torch.compile than eager mode
  • ✓Verified signal present: torch.compile recompiles on shape change
  • ✓A targeted fix from the "How to fix it" section eliminates or substantially reduces the symptom within one validation pass.

Root cause

  • torch.compile keeps compiled graphs in memory
  • Recompilation on dynamic shapes
  • Different configs for different model parts
  • Guard evaluation overhead

The fix and how to prevent it

Searchable error signature

search key
torch.compile causes OOM
Memory higher with torch.compile than eager mode
torch.compile recompiles on shape change

Use this text as a lookup key in logs and upstream issue trackers. It is not presented as a captured customer log. Confirm the cause from your own preceding events, versions, configuration and the cited references.

The fix and the prevention pattern

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Don't just read the fix, diagnose your run

The encyclopedia tells you what went wrong. Denpex tells you what went wrong in YOUR training run. With your logs, your config, and your stack.