{"record":{"id":"a4ff86ff2b9e8730","repo":"rohitg00/ai-engineering-from-scratch","slug":"rank-rank-failed-payload-error","errorCode":null,"errorMessage":"rank {rank} failed: {payload[\"error\"]}","messagePattern":"rank (.+?) failed: (.+?)","errorType":"exception","errorClass":"RuntimeError","httpStatus":null,"severity":"error","filePath":"phases/19-capstone-projects/48-distributed-fsdp-ddp/code/main.py","lineNumber":355,"sourceCode":"            rank, payload, diff = result_queue.get(timeout=1.0)\n        except Exception:\n            continue\n        results[rank] = payload\n        if diff > max_diff:\n            max_diff = diff\n        collected += 1\n    for p in procs:\n        p.join(timeout=max(1.0, deadline - time.time()))\n    if any(p.is_alive() for p in procs):\n        for p in procs:\n            if p.is_alive():\n                p.terminate()\n        raise RuntimeError(\"ranks did not finish in time\")\n    if collected < world_size:\n        raise RuntimeError(f\"only got {collected}/{world_size} results: {results}\")\n    for rank, payload in results.items():\n        if \"error\" in payload:\n            raise RuntimeError(f\"rank {rank} failed: {payload['error']}\")\n    param_sums = {r: results[r][\"post_param_sum\"] for r in results}\n    spread = max(param_sums.values()) - min(param_sums.values())\n    losses = [results[r][\"final_loss\"] for r in results]\n    grad_norm = results[0][\"grad_norm_after_all_reduce\"]\n    return {\n        \"world_size\": world_size,\n        \"backend\": backend,\n        \"param_sum_per_rank\": param_sums,\n        \"param_sum_spread\": spread,\n        \"losses\": losses,\n        \"grad_norm_after_all_reduce\": grad_norm,\n        \"manual_all_reduce_max_diff_vs_single_process\": max_diff,\n        \"fsdp_round_trip_all_ranks_ok\": all(results[r][\"fsdp_round_trip_ok\"] for r in results),\n    }\n\n\ndef write_demo(payload: Dict[str, object], path: Path) -> None:\n    path.parent.mkdir(parents=True, exist_ok=True)","sourceCodeStart":337,"sourceCodeEnd":373,"githubUrl":"https://github.com/rohitg00/ai-engineering-from-scratch/blob/39ea8a1c6d0b61f071226eff7ede4d4105fed820/phases/19-capstone-projects/48-distributed-fsdp-ddp/code/main.py#L337-L373","documentation":"Error \"rank {rank} failed: {payload[\"error\"]}\" thrown in rohitg00/ai-engineering-from-scratch.","triggerScenarios":"Thrown at phases/19-capstone-projects/48-distributed-fsdp-ddp/code/main.py:355 when the library encounters an invalid state.","commonSituations":"See trigger scenarios.","solutions":[],"exampleFix":null,"handlingStrategy":null,"validationCode":null,"typeGuard":null,"tryCatchPattern":null,"preventionTips":[],"tags":[],"backgroundTag":null,"analyzedSha":"39ea8a1c6d0b61f071226eff7ede4d4105fed820","analyzedAt":"2026-08-26T03:13:46.626Z","schemaVersion":2},"datasetVersion":"2026-08-26T07:17:17.940Z"}