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Tensor Views Memory Leak

Tensor views (slices, reshapes, transposes) can hold references to large base tensors, preventing memory release.

Quick answer

Tensor views (slices, reshapes, transposes) can hold references to large base tensors, preventing memory release.

Symptom
torch.cuda.memory_allocated() shows large tensors
Root cause
Tensor view holds reference to base tensor. Base tensor not garbage collected. Python references prevent tensor release.
Recommended fix
Use .clone() if you need a copy: x.clone()
How Denpex helps
Denpex investigates Tensor Views Memory Leak 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#tensor-views#memory-leak#reference-counting#memory#debugging

What this failure is

Tensor Views Memory Leak is a Memory failure seen during ML training runs. Tensor views (slices, reshapes, transposes) can hold references to large base tensors, preventing memory release. Common tags: Tensor Views, Memory Leak, Reference Counting, Memory.

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Why it happens (the mechanism)

Tensor view holds reference to base tensor. Base tensor not garbage collected. Python references prevent tensor release. Storage vs tensor object confusion. 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 is higher than expected after slicing
  • Deleting a tensor doesn't free memory
  • Memory accumulates with many tensor operations

Common symptoms and what they mean

SymptomWhy it happens
GPU memory grows with operationsTensor view holds reference to base tensor
torch.cuda.memory_allocated() shows large tensorsBase tensor not garbage collected
Memory not freed after model deletionPython references prevent tensor release

Which systems are affected

  • Heavy tensor manipulation code
  • Large batch tensor slicing
  • Complex model architectures

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: GPU memory grows with operations
  • ✓Verified signal present: torch.cuda.memory_allocated() shows large tensors
  • ✓Verified signal present: Memory not freed after model deletion
  • ✓A targeted fix from the "How to fix it" section eliminates or substantially reduces the symptom within one validation pass.

Root cause

  • Tensor view holds reference to base tensor
  • Base tensor not garbage collected
  • Python references prevent tensor release
  • Storage vs tensor object confusion

The fix and how to prevent it

Searchable error signature

search key
torch.cuda.memory_allocated() shows large tensors

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The fix and the prevention pattern

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Don't just read the fix, diagnose your run

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