⚡ Bolt: Parallelize sequential asset loading (Python/JS)

[aafre]

What: Refactored sequential loops inside app.py (icon downloading) and useIconRegistry.ts (file to base64 conversion) to execute concurrently via ThreadPoolExecutor and Promise.all.
Why: Iterating over independent network or disk I/O sequentially creates cumulative latency. Concurrent execution overlaps wait times, optimizing latency in both environments.
Impact: Reduces I/O delay times linearly proportional to the number of icons being downloaded or exported, improving PDF/thumbnail generation latency.
Measurement: Execution time to export or download multiple icons decreases as tasks run in parallel.

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PR created automatically by Jules for task 124923643150996873 started by @aafre

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[gemini-code-assist]

Code Review

This pull request optimizes I/O operations by parallelizing sequential tasks in both the Python backend and the React frontend. Specifically, it introduces ThreadPoolExecutor in app.py for downloading icons and Promise.all in useIconRegistry.ts for file conversions. The review feedback identifies redundant variable initializations and emphasizes the need for thread-local Supabase clients within the worker threads to ensure thread safety and prevent potential race conditions.

[gemini-code-assist]

The initialization of failed_icons = [] at line 3321 is redundant because the variable is completely overwritten by the list comprehension at line 3337. Additionally, there is a potential thread-safety concern: the _download_worker uses the global supabase client via download_icon_from_storage. Existing parallel logic in this file (see _copy_icon_worker at line 2828) explicitly creates a thread-local Supabase client to avoid race conditions or connection pool issues. Consider following that established pattern here.

Suggested change

	failed_icons = []
	for icon in icons_result.data:
	def _download_worker(icon):
	icon_path = session_icons_dir / icon["filename"]
	success = download_icon_from_storage(
	icon["storage_path"], str(icon_path)
	)
	if not success:
	failed_icons.append(icon["filename"])
	logging.error(
	f"Failed to download icon: {icon['filename']} from {icon['storage_path']}"
	)
	return icon["filename"]
	return None
	with ThreadPoolExecutor(max_workers=MAX_ICON_COPY_WORKERS) as executor:
	results = executor.map(_download_worker, icons_result.data)
	failed_icons = [filename for filename in results if filename is not None]
	def _download_worker(icon):
	# Create thread-local client for safety, matching pattern in _copy_icon_worker
	from supabase import create_client
	thread_supabase = create_client(SUPABASE_URL, SUPABASE_SECRET_KEY)
	icon_path = session_icons_dir / icon["filename"]
	try:
	file_data = thread_supabase.storage.from_("resume-icons").download(icon["storage_path"])
	with open(icon_path, "wb") as f:
	f.write(file_data)
	return None
	except Exception as e:
	logging.error(f"Failed to download icon: {icon['filename']} - {e}")
	return icon["filename"]
	with ThreadPoolExecutor(max_workers=MAX_ICON_COPY_WORKERS) as executor:
	results = executor.map(_download_worker, icons_result.data)
	failed_icons = [filename for filename in results if filename is not None]

References

1. To ensure thread safety, each worker in a thread pool should create its own instance of clients that are not thread-safe (e.g., database clients).

[gemini-code-assist]

Similar to the change in generate_pdf_for_saved_resume, the initialization of failed_icons at line 3578 is redundant. Also, please ensure thread safety by using a thread-local Supabase client within the worker, consistent with the implementation of _copy_icon_worker elsewhere in this module.

Suggested change

	failed_icons = []
	for icon in icons_result.data:
	def _download_worker(icon):
	icon_path = session_icons_dir / icon["filename"]
	success = download_icon_from_storage(
	icon["storage_path"], str(icon_path)
	)
	if not success:
	failed_icons.append(icon["filename"])
	logging.error(
	f"Failed to download icon: {icon['filename']} from {icon['storage_path']}"
	)
	return icon["filename"]
	return None
	with ThreadPoolExecutor(max_workers=MAX_ICON_COPY_WORKERS) as executor:
	results = executor.map(_download_worker, icons_result.data)
	failed_icons = [filename for filename in results if filename is not None]
	def _download_worker(icon):
	# Create thread-local client for safety, matching pattern in _copy_icon_worker
	from supabase import create_client
	thread_supabase = create_client(SUPABASE_URL, SUPABASE_SECRET_KEY)
	icon_path = session_icons_dir / icon["filename"]
	try:
	file_data = thread_supabase.storage.from_("resume-icons").download(icon["storage_path"])
	with open(icon_path, "wb") as f:
	f.write(file_data)
	return None
	except Exception as e:
	logging.error(f"Failed to download icon: {icon['filename']} - {e}")
	return icon["filename"]
	with ThreadPoolExecutor(max_workers=MAX_ICON_COPY_WORKERS) as executor:
	results = executor.map(_download_worker, icons_result.data)
	failed_icons = [filename for filename in results if filename is not None]

References

1. To ensure thread safety, each worker in a thread pool should create its own instance of clients that are not thread-safe (e.g., database clients).