perf: Optimize PDF processing with parallel extraction and single-render highlights
Phase 1 - PDF Highlighting Optimization: - Render each page ONCE instead of once per chunk (N chunks = 1 render, not N) - Use PIL to draw bounding boxes on copied base images (fast) instead of re-rendering page via pymupdf (slow) - Add _find_chunk_bbox() to extract bbox without modifying page Phase 2 - Parallel Page Extraction: - Use anyio task group with run_sync() for parallel page extraction - Each page extracted in separate thread via anyio.to_thread.run_sync() - Event loop stays responsive during extraction - Remove obsolete _process_sync() method Expected improvement: 30-50% reduction in total PDF processing time. 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-Authored-By: Claude <noreply@anthropic.com>
This commit is contained in:
Chris Coutinho
@@ -99,129 +99,132 @@ class PyMuPDFProcessor(DocumentProcessor):
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try:
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if progress_callback:
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await progress_callback(0, 100, "Processing PDF in background thread")
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await progress_callback(0, 100, "Opening PDF document")
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# Run CPU-bound PDF processing in thread pool to avoid blocking event loop
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result = await anyio.to_thread.run_sync( # type: ignore[attr-defined]
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self._process_sync,
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content,
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filename,
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# Open document and extract metadata in thread
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doc = await anyio.to_thread.run_sync( # type: ignore[attr-defined]
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lambda: pymupdf.open("pdf", content)
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)
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metadata = self._extract_metadata(doc, filename)
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metadata["file_size"] = len(content)
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page_count = doc.page_count
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if progress_callback:
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await progress_callback(10, 100, f"Extracting {page_count} pages")
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# Prepare image directory if needed
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pdf_image_dir = None
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if self.extract_images:
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pdf_id = filename.replace("/", "_") if filename else "unknown"
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pdf_image_dir = self.image_dir / pdf_id
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pdf_image_dir.mkdir(exist_ok=True, parents=True)
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# OPTIMIZATION: Extract pages in parallel using anyio task group
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page_texts = await self._extract_pages_parallel(
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doc, page_count, pdf_image_dir
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)
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if progress_callback:
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await progress_callback(90, 100, "Building result")
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# Calculate page boundaries (sequential, fast)
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page_boundaries = []
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current_offset = 0
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for page_num, page_md in enumerate(page_texts):
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page_boundaries.append(
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{
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"page": page_num + 1,
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"start_offset": current_offset,
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"end_offset": current_offset + len(page_md),
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}
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)
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current_offset += len(page_md)
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# Collect image paths
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image_paths = []
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if pdf_image_dir and pdf_image_dir.exists():
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image_paths = [str(p) for p in pdf_image_dir.glob("*")]
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# Build final text and metadata
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md_text = "".join(page_texts)
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metadata["has_images"] = len(image_paths) > 0
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if image_paths:
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metadata["image_count"] = len(image_paths)
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metadata["image_paths"] = image_paths
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metadata["page_boundaries"] = page_boundaries
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# Close document
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doc.close()
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if progress_callback:
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await progress_callback(100, 100, "Processing complete")
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return result
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logger.info(
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f"Successfully processed PDF {filename or '<bytes>'}: "
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f"{metadata['page_count']} pages, {len(md_text)} chars, "
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f"{metadata.get('image_count', 0)} images"
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)
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return ProcessingResult(
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text=md_text,
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metadata=metadata,
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processor=self.name,
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success=True,
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)
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except Exception as e:
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error_msg = f"Failed to process PDF {filename or '<bytes>'}: {e}"
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logger.error(error_msg, exc_info=True)
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raise ProcessorError(error_msg) from e
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def _process_sync(
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async def _extract_pages_parallel(
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self,
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content: bytes,
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filename: Optional[str] = None,
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) -> ProcessingResult:
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"""Synchronous PDF processing (runs in thread pool).
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doc: pymupdf.Document,
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page_count: int,
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pdf_image_dir: pathlib.Path | None,
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) -> list[str]:
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"""Extract text from all pages in parallel using anyio.
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Args:
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content: PDF document bytes
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filename: Optional filename for better error messages
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doc: Opened PyMuPDF document
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page_count: Number of pages to extract
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pdf_image_dir: Directory for extracted images (or None)
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Returns:
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ProcessingResult with extracted text and metadata
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Raises:
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Exception: If PDF processing fails
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List of page texts in order
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"""
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# Open PDF from bytes
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doc = pymupdf.open("pdf", content)
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import anyio
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# Extract metadata from PDF
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metadata = self._extract_metadata(doc, filename)
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results: list[str | None] = [None] * page_count
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# Add file size to metadata
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metadata["file_size"] = len(content)
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async def extract_one(page_num: int) -> None:
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"""Extract single page in thread pool."""
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# Extract text page-by-page to preserve page boundaries
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# pymupdf.layout.activate() causes page_chunks=True to return a string,
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# so we manually extract text per page instead.
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page_boundaries = []
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current_offset = 0
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full_text_parts = []
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image_paths = []
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for page_num in range(doc.page_count):
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if self.extract_images:
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# Generate unique directory for this PDF's images
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pdf_id = filename.replace("/", "_") if filename else "unknown"
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pdf_image_dir = self.image_dir / pdf_id
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pdf_image_dir.mkdir(exist_ok=True, parents=True)
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# Extract page as markdown with images
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page_md = pymupdf4llm.to_markdown(
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def do_extract() -> str:
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return pymupdf4llm.to_markdown(
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doc,
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pages=[page_num], # Extract single page
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write_images=True,
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image_path=pdf_image_dir,
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page_chunks=False, # Single page, no chunking needed
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pages=[page_num],
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write_images=self.extract_images,
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image_path=pdf_image_dir if self.extract_images else None,
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page_chunks=False,
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)
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# Collect image paths
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if pdf_image_dir.exists():
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page_images = [str(p) for p in pdf_image_dir.glob("*")]
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image_paths.extend(page_images)
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else:
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# Extract page as markdown without images
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page_md = pymupdf4llm.to_markdown(
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doc,
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pages=[page_num], # Extract single page
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write_images=False,
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page_chunks=False, # Single page, no chunking needed
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)
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results[page_num] = await anyio.to_thread.run_sync(do_extract) # type: ignore[attr-defined]
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# Store page text
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full_text_parts.append(page_md)
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# Run all page extractions in parallel
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async with anyio.create_task_group() as tg:
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for page_num in range(page_count):
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tg.start_soon(extract_one, page_num)
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# Store boundary info: {page (1-indexed), start, end}
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page_boundaries.append(
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{
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"page": page_num + 1, # Convert to 1-indexed
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"start_offset": current_offset,
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"end_offset": current_offset + len(page_md),
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}
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)
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# Verify all pages extracted
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final_results: list[str] = []
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for i, text in enumerate(results):
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if text is None:
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raise ProcessorError(f"Page {i} extraction failed")
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final_results.append(text)
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current_offset += len(page_md)
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# Join all page texts
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md_text = "".join(full_text_parts)
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# Store image metadata
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metadata["has_images"] = len(image_paths) > 0
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if image_paths:
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metadata["image_count"] = len(image_paths)
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metadata["image_paths"] = image_paths
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# Add page boundaries to metadata for chunker to use
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metadata["page_boundaries"] = page_boundaries
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# Close the document
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doc.close()
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logger.info(
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f"Successfully processed PDF {filename or '<bytes>'}: "
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f"{metadata['page_count']} pages, {len(md_text)} chars, "
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f"{metadata.get('image_count', 0)} images"
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)
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return ProcessingResult(
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text=md_text,
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metadata=metadata,
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processor=self.name,
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success=True,
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)
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return final_results
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def _extract_metadata(
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self, doc: pymupdf.Document, filename: Optional[str]
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@@ -393,6 +393,65 @@ class PDFHighlighter:
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return clean_text if clean_text else None
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@staticmethod
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def _find_chunk_bbox(
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page: pymupdf.Page,
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chunk_text: str,
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page_relative_start: int,
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page_relative_end: int,
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page_text_length: int,
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) -> tuple[float, float, float, float] | None:
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"""Find bounding box for a chunk without modifying the page.
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Returns (x0, y0, x1, y1) in page coordinates, or None if not found.
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"""
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page_rect = page.rect
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# Strip markdown for searching
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search_text = PDFHighlighter.strip_markdown(chunk_text)
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# Try to find chunk location using text search
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anchor_rect = None
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search_phrases = []
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# Build search phrases from chunk text
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sentences = re.split(r"[.!?]\s+", search_text)
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for sentence in sentences[:3]:
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sentence = sentence.strip()
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if len(sentence) >= 20:
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search_phrases.append(sentence[:80])
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if len(sentence) >= 40:
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search_phrases.append(sentence[:40])
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# Also try first N characters
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if len(search_text) >= 30:
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search_phrases.append(search_text[:60])
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search_phrases.append(search_text[:30])
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for phrase in search_phrases:
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if not phrase:
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continue
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rects = page.search_for(phrase.strip())
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if rects:
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anchor_rect = rects[0]
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break
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if not anchor_rect:
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return None
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# Calculate chunk height based on character count
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chunk_chars = len(search_text)
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estimated_lines = max(1, chunk_chars / 60)
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estimated_height = estimated_lines * 14
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# Build bounding box
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return (
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page_rect.x0 + 30, # Left margin
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anchor_rect.y0 - 5, # Start slightly above anchor
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page_rect.x1 - 30, # Right margin
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min(anchor_rect.y0 + estimated_height + 10, page_rect.y1 - 30),
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)
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@staticmethod
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def highlight_chunk_on_page(
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page: pymupdf.Page,
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@@ -739,20 +798,32 @@ class PDFHighlighter:
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f"Chunks distributed across {len(chunks_by_page)} unique pages"
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)
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# Process each chunk, rendering with only its own highlights
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# Store original page contents to restore between chunks
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page_contents_cache: dict[int, list[bytes]] = {}
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# OPTIMIZATION: Render each page ONCE, then draw highlights using PIL
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# This avoids expensive page.get_pixmap() calls per chunk
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from io import BytesIO
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from PIL import Image, ImageDraw
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# PIL color for bounding box (RGB tuple)
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rgb = PDFHighlighter.COLORS.get(color, PDFHighlighter.COLORS["yellow"])
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pil_color = tuple(int(c * 255) for c in rgb)
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fill_color = (255, 255, 178, 38) # Light yellow with alpha
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for page_num, page_chunks in chunks_by_page.items():
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page = doc[page_num - 1]
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# Cache original page contents (before any highlights added)
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# xref is the PDF object reference for each content stream
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if page_num not in page_contents_cache:
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page_contents_cache[page_num] = []
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xrefs = page.get_contents()
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for xref in xrefs:
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page_contents_cache[page_num].append(doc.xref_stream(xref))
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# Render page ONCE to get base image (most expensive operation)
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mat = pymupdf.Matrix(zoom, zoom)
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base_pix = page.get_pixmap(matrix=mat, alpha=False)
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base_png = base_pix.tobytes("png")
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# Convert to PIL Image for fast highlight drawing
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base_image = Image.open(BytesIO(base_png)).convert("RGBA")
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page_rect = page.rect
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logger.debug(
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f"Page {page_num}: rendered once, processing {len(page_chunks)} chunks"
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)
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for (
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chunk_index,
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@@ -761,42 +832,48 @@ class PDFHighlighter:
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page_text_length,
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) in page_chunks:
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try:
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# Restore original page contents to remove previous highlights
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# Highlights are drawn shapes, not annotations, so we must
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# restore the content stream to clear them
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xrefs = page.get_contents()
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for i, xref in enumerate(xrefs):
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if i < len(page_contents_cache[page_num]):
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doc.update_stream(
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xref, page_contents_cache[page_num][i]
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)
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# Add highlights for this chunk with region constraint
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page_relative_start = chunk_page_info["page_relative_start"]
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page_relative_end = chunk_page_info["page_relative_end"]
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highlight_count = PDFHighlighter.highlight_chunk_on_page(
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# Find chunk bounding box using text search
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bbox = PDFHighlighter._find_chunk_bbox(
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page,
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chunk_text,
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color,
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page_relative_start=page_relative_start,
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page_relative_end=page_relative_end,
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page_text_length=page_text_length,
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chunk_page_info["page_relative_start"],
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chunk_page_info["page_relative_end"],
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page_text_length,
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)
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if highlight_count == 0:
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logger.warning(f"Chunk {chunk_index}: no highlights added")
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if bbox is None:
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logger.warning(f"Chunk {chunk_index}: could not find bbox")
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continue
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# Render page to PNG
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mat = pymupdf.Matrix(zoom, zoom)
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pix = page.get_pixmap(matrix=mat, alpha=False)
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png_bytes = pix.tobytes("png")
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# Copy base image and draw highlight using PIL (fast!)
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chunk_image = base_image.copy()
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draw = ImageDraw.Draw(chunk_image, "RGBA")
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results[chunk_index] = (png_bytes, page_num, highlight_count)
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# Scale bbox coordinates to pixmap coordinates
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scale_x = base_pix.width / page_rect.width
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scale_y = base_pix.height / page_rect.height
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pil_bbox = (
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int(bbox[0] * scale_x),
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int(bbox[1] * scale_y),
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int(bbox[2] * scale_x),
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int(bbox[3] * scale_y),
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)
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# Draw semi-transparent fill
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draw.rectangle(pil_bbox, fill=fill_color)
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# Draw dashed border (PIL doesn't support dashes, use solid)
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draw.rectangle(pil_bbox, outline=pil_color, width=3)
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# Convert back to PNG bytes
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output = BytesIO()
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chunk_image.convert("RGB").save(output, format="PNG")
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png_bytes = output.getvalue()
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results[chunk_index] = (png_bytes, page_num, 1)
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logger.debug(
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f"Chunk {chunk_index}: {len(png_bytes):,} bytes, "
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f"page {page_num}, {highlight_count} highlights"
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f"page {page_num}, bbox {pil_bbox}"
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)
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except Exception as e:
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Reference in New Issue
Block a user