3d2da94ce2
- Complete transformer implementation from scratch - Training pipeline with gradient accumulation and mixed precision - Optimized inference with KV caching - Multi-format data processing (PDFs, images, code, text) - Comprehensive documentation - Apache 2.0 license - Example training plots included in docs/images/
268 lines
8.6 KiB
Python
268 lines
8.6 KiB
Python
"""
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Prefetching mechanism for parallel data loading and processing
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Optimizes RAG systems by prefetching retrieval results
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"""
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import torch
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from torch.utils.data import DataLoader
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from typing import List, Dict, Optional, Callable, Any
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from threading import Thread
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from queue import Queue
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import time
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class PrefetchDataLoader:
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"""
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DataLoader with prefetching for parallel data loading.
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Reduces GPU idle time by prefetching batches in background threads.
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"""
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def __init__(
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self,
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dataloader: DataLoader,
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prefetch_factor: int = 2,
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device: torch.device = None,
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):
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"""
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Args:
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dataloader: Base DataLoader to wrap
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prefetch_factor: Number of batches to prefetch
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device: Device to prefetch batches to
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"""
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self.dataloader = dataloader
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self.prefetch_factor = prefetch_factor
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self.device = device
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self.queue = Queue(maxsize=prefetch_factor)
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self.thread = None
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self._stop_thread = False
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def _prefetch_worker(self):
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"""Worker thread that prefetches batches."""
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for batch in self.dataloader:
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if self._stop_thread:
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break
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# Move to device if specified
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if self.device is not None:
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batch = {k: v.to(self.device, non_blocking=True)
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for k, v in batch.items()}
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self.queue.put(batch)
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self.queue.put(None) # Signal end of data
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def __iter__(self):
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"""Start prefetching thread and return iterator."""
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self._stop_thread = False
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self.thread = Thread(target=self._prefetch_worker, daemon=True)
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self.thread.start()
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return self
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def __next__(self):
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"""Get next prefetched batch."""
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batch = self.queue.get()
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if batch is None:
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raise StopIteration
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return batch
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def __len__(self):
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"""Return length of underlying dataloader."""
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return len(self.dataloader)
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def stop(self):
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"""Stop prefetching thread."""
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self._stop_thread = True
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if self.thread is not None:
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self.thread.join()
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class LookaheadRetriever:
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"""
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Lookahead retrieval mechanism for RAG systems.
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Prefetches retrieval results for anticipated queries.
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"""
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def __init__(
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self,
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retrieval_fn: Callable[[str], List[Dict]],
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lookahead_window: int = 3,
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prefetch_queue_size: int = 10,
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):
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"""
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Args:
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retrieval_fn: Function that takes a query and returns retrieved documents
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lookahead_window: Number of queries to look ahead
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prefetch_queue_size: Maximum size of prefetch queue
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"""
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self.retrieval_fn = retrieval_fn
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self.lookahead_window = lookahead_window
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self.prefetch_queue_size = prefetch_queue_size
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self.prefetch_queue: Queue = Queue(maxsize=prefetch_queue_size)
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self.prefetch_thread: Optional[Thread] = None
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self._stop_thread = False
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def _prefetch_worker(self, query_queue: Queue):
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"""Worker thread that prefetches retrieval results."""
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while not self._stop_thread:
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try:
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query = query_queue.get(timeout=1.0)
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if query is None:
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break
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# Perform retrieval
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results = self.retrieval_fn(query)
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# Add to prefetch queue
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try:
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self.prefetch_queue.put((query, results), timeout=0.1)
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except:
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pass # Queue full, skip
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except:
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continue
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def start_prefetching(self, query_stream: List[str]):
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"""Start prefetching retrieval results for query stream."""
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query_queue = Queue()
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# Add queries to queue
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for query in query_stream:
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query_queue.put(query)
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query_queue.put(None) # Signal end
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self._stop_thread = False
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self.prefetch_thread = Thread(target=self._prefetch_worker, args=(query_queue,), daemon=True)
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self.prefetch_thread.start()
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def get(self, query: str, timeout: float = 1.0) -> Optional[List[Dict]]:
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"""
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Get retrieval results, checking prefetch queue first.
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Args:
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query: Query string
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timeout: Timeout for checking prefetch queue
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Returns:
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Retrieved documents or None if not found
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"""
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# Check prefetch queue
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while not self.prefetch_queue.empty():
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try:
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cached_query, results = self.prefetch_queue.get(timeout=timeout)
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if cached_query == query:
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return results
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# Put back if not matching
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self.prefetch_queue.put((cached_query, results))
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except:
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break
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# Fallback to direct retrieval
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return self.retrieval_fn(query)
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def stop(self):
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"""Stop prefetching thread."""
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self._stop_thread = True
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if self.prefetch_thread is not None:
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self.prefetch_thread.join()
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class BatchPrefetcher:
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"""
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Batched prefetching for multiple queries.
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Groups queries into batches for efficient retrieval.
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"""
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def __init__(
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self,
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batch_retrieval_fn: Callable[[List[str]], List[List[Dict]]],
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batch_size: int = 8,
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prefetch_factor: int = 2,
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):
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"""
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Args:
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batch_retrieval_fn: Function that takes list of queries and returns list of results
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batch_size: Size of batches for retrieval
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prefetch_factor: Number of batches to prefetch
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"""
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self.batch_retrieval_fn = batch_retrieval_fn
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self.batch_size = batch_size
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self.prefetch_factor = prefetch_factor
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self.prefetch_queue: Queue = Queue(maxsize=prefetch_factor)
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self.prefetch_thread: Optional[Thread] = None
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self._stop_thread = False
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def _prefetch_worker(self, query_queue: Queue):
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"""Worker thread that prefetches batches of retrieval results."""
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batch = []
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while not self._stop_thread:
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try:
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query = query_queue.get(timeout=1.0)
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if query is None:
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# Process remaining batch
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if batch:
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results = self.batch_retrieval_fn(batch)
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for q, r in zip(batch, results):
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self.prefetch_queue.put((q, r))
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break
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batch.append(query)
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# Process batch when full
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if len(batch) >= self.batch_size:
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results = self.batch_retrieval_fn(batch)
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for q, r in zip(batch, results):
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try:
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self.prefetch_queue.put((q, r), timeout=0.1)
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except:
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pass # Queue full
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batch = []
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except:
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continue
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def start_prefetching(self, query_stream: List[str]):
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"""Start prefetching retrieval results for query stream."""
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query_queue = Queue()
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for query in query_stream:
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query_queue.put(query)
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query_queue.put(None) # Signal end
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self._stop_thread = False
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self.prefetch_thread = Thread(target=self._prefetch_worker, args=(query_queue,), daemon=True)
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self.prefetch_thread.start()
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def get(self, query: str, timeout: float = 1.0) -> Optional[List[Dict]]:
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"""
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Get retrieval results from prefetch queue.
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Args:
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query: Query string
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timeout: Timeout for checking prefetch queue
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Returns:
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Retrieved documents or None if not found
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"""
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# Check prefetch queue
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while not self.prefetch_queue.empty():
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try:
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cached_query, results = self.prefetch_queue.get(timeout=timeout)
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if cached_query == query:
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return results
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# Put back if not matching
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self.prefetch_queue.put((cached_query, results))
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except:
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break
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return None
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def stop(self):
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"""Stop prefetching thread."""
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self._stop_thread = True
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if self.prefetch_thread is not None:
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self.prefetch_thread.join()
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