DeepSpeed Training Hangs at Start with HuggingFace auto_find_batch_size
DeepSpeed (ZeRO offload) training with HuggingFace Trainer auto_find_batch_size=True hangs right after model load at 0/N steps. The batch-size auto-search re-initializes the engine and desynchronizes collectives across ranks. Disable auto_find_batch_size for distributed runs.
DeepSpeed (ZeRO offload) training with HuggingFace Trainer auto_find_batch_size=True hangs right after model load at 0/N steps.
What this failure is
DeepSpeed Training Hangs at Start with HuggingFace auto_find_batch_size is a Training Stability failure seen during ML training runs. DeepSpeed (ZeRO offload) training with HuggingFace Trainer auto_find_batch_size=True hangs right after model load at 0/N steps. The batch-size auto-search re-initializes the engine and desynchronizes collectives across ranks. Disable auto_find_batch_size for distributed runs. Common tags: Deepspeed, Huggingface Trainer, Auto_find_batch_size, Hang.
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Why it happens (the mechanism)
Auto_find_batch_size retries the first step with progressively smaller batch sizes, re-initializing or re-synchronizing the DeepSpeed engine each attempt. These re-inits desync NCCL collectives across ranks, so the ranks deadlock waiting on each other. 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
- Training hangs at 0% right after model/optimizer load
- No error, just a stalled progress bar
- Removing auto_find_batch_size unblocks the run
Common symptoms and what they mean
| Symptom | Why it happens |
|---|---|
| Progress bar stuck at 0/N with cpu_adam loaded | auto_find_batch_size retries the first step with progressively smaller batch sizes, re-initializing or re-synchronizing the DeepSpeed engine each attempt |
| Multi-GPU DeepSpeed run never starts stepping | These re-inits desync NCCL collectives across ranks, so the ranks deadlock waiting on each other |
| Hang correlates with auto_find_batch_size=True | auto_find_batch_size retries the first step with progressively smaller batch sizes, re-initializing or re-synchronizing the DeepSpeed engine each attempt |
Which systems are affected
- DeepSpeed ZeRO-2/3 with optimizer/param offload
- HuggingFace Trainer auto_find_batch_size
- Multi-rank launches
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: Progress bar stuck at 0/N with cpu_adam loaded
- ✓Verified signal present: Multi-GPU DeepSpeed run never starts stepping
- ✓Verified signal present: Hang correlates with auto_find_batch_size=True
- ✓A targeted fix from the "How to fix it" section eliminates or substantially reduces the symptom within one validation pass.
The fix and the prevention pattern
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Diagnose this failure in VS Code
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Install the free VS Code extensionDeepSpeed errors in context
DeepSpeed changes when parameters, gradients and optimizer state are created, partitioned, gathered and offloaded. The hub separates ZeRO, memory, checkpoint and pipeline failures by lifecycle phase.
Compare every deepspeed error side by sideRelated failures to investigate next
Root cause
- auto_find_batch_size retries the first step with progressively smaller batch sizes, re-initializing or re-synchronizing the DeepSpeed engine each attempt
- These re-inits desync NCCL collectives across ranks, so the ranks deadlock waiting on each other
The fix and how to prevent it
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