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Optimizer State Memory

Optimizer state memory (Adam: 2x model size, AdamW: 2x) can exceed model size memory, dominating total usage.

Quick answer

Optimizer state memory (Adam: 2x model size, AdamW: 2x) can exceed model size memory, dominating total usage.

Root cause
Adam stores 2x model size (m and v). FP32 master weights for mixed precision. Gradient accumulation adds to state.
Recommended fix
Use Adam 8-bit: bitsandbytes.optim.Adam8bit
How Denpex helps
Denpex investigates Optimizer State 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#optimizer#adam#adamw#state#memory

What this failure is

Optimizer State Memory is a Memory failure seen during ML training runs. Optimizer state memory (Adam: 2x model size, AdamW: 2x) can exceed model size memory, dominating total usage. Common tags: Optimizer, Adam, Adamw, State.

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Why it happens (the mechanism)

Adam stores 2x model size (m and v). FP32 master weights for mixed precision. Gradient accumulation adds to state. Optimizer state not offloaded. 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 usage much higher than model size
  • Adam training OOM despite small model
  • Optimizer state uses more memory than expected

Common symptoms and what they mean

SymptomWhy it happens
Adam optimizer memory is 2x model sizeAdam stores 2x model size (m and v)
AdamW with weight decay adds to stateFP32 master weights for mixed precision
Mixed precision optimizer state with FP32 master weightsGradient accumulation adds to state

Which systems are affected

  • AdamW training
  • Large model training
  • Mixed precision training

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: Adam optimizer memory is 2x model size
  • ✓Verified signal present: AdamW with weight decay adds to state
  • ✓Verified signal present: Mixed precision optimizer state with FP32 master weights
  • ✓A targeted fix from the "How to fix it" section eliminates or substantially reduces the symptom within one validation pass.

Root cause

  • Adam stores 2x model size (m and v)
  • FP32 master weights for mixed precision
  • Gradient accumulation adds to state
  • Optimizer state not offloaded

The fix and how to prevent it

The fix and the prevention pattern

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Don't just read the fix, diagnose your run

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