⚡ Bolt: Unblock FastAPI event loop for higher concurrency#83
⚡ Bolt: Unblock FastAPI event loop for higher concurrency#83Adityasingh-8858 wants to merge 1 commit into
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Switched from synchronous Groq client to `AsyncGroq` and wrapped all synchronous SQLite persistence calls in `asyncio.to_thread`. This resolves severe concurrency bottlenecks by ensuring the FastAPI main event loop is never blocked by external I/O operations. Co-authored-by: Deepaksingh7238 <110552872+Deepaksingh7238@users.noreply.github.com>
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Pull request overview
This PR aims to improve FastAPI concurrency by eliminating event-loop blocking work in async endpoints, primarily by switching Groq calls to the async client and offloading synchronous SQLite persistence operations to a thread pool.
Changes:
- Switched Groq usage in
backend/main.pyfromGroqtoAsyncGroqand awaited LLM generation calls in/ai-voiceand/initiate-transfer. - Offloaded synchronous SQLite persistence calls (
create_transfer_record,set_agent_b,list_transfers,get_transfer) usingawait asyncio.to_thread(...). - Added two local verification scripts under
backend/tests/plus a short engineering journal entry in.jules/bolt.md.
Reviewed changes
Copilot reviewed 4 out of 4 changed files in this pull request and generated 2 comments.
| File | Description |
|---|---|
backend/main.py |
Uses AsyncGroq with await and offloads synchronous persistence work via asyncio.to_thread to reduce event-loop blocking. |
backend/tests/verify_groq_blocking.py |
Adds a script intended to demonstrate sync Groq blocking behavior. |
backend/tests/verify_blocking.py |
Adds a script to demonstrate generic blocking vs asyncio.to_thread offloading behavior. |
.jules/bolt.md |
Adds a short note documenting the “Bolt” learning/action about avoiding blocking calls in async endpoints. |
Comments suppressed due to low confidence (1)
backend/main.py:496
- Using
asyncio.to_thread(...)requires Python 3.9+, and this file also uses PEP 604 union types (str | None) which require Python 3.10+. The README currently documents Python 3.8+; please update the documented runtime requirement (or provide a 3.8-compatible fallback such asloop.run_in_executor).
# ⚡ Bolt: Offload synchronous DB operations to thread pool
rec_id = await asyncio.to_thread(
persistence.create_transfer_record,
room_name=request.room_name or "unknown",
agent_a=request.agent_a_identity or "unknown",
summary=summary,
call_context=request.call_context
)
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| from groq import Groq | ||
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| def test_blocking(): | ||
| client = Groq(api_key="sk-test", max_retries=0) | ||
| try: | ||
| client.chat.completions.create( | ||
| messages=[{"role": "user", "content": "hi"}], | ||
| model="llama3-8b-8192" | ||
| ) |
| ticks = await task | ||
| print(f"Ticks with sync blocking: {ticks}") | ||
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| asyncio.run(main()) |
💡 What:
Groqclient imports withAsyncGroq./ai-voiceand/initiate-transferto correctlyawaittheir network requests.persistencedatabase calls (create_transfer_record,list_transfers,set_agent_b,get_transfer) to a thread pool viaawait asyncio.to_thread..jules/bolt.md.🎯 Why:
Synchronous network requests and database operations inside FastAPI
async defendpoints block the event loop entirely. This means while waiting for Groq LLM completions or disk I/O, the backend would stall and become completely unresponsive to other concurrent incoming HTTP connections, severely reducing throughput.📊 Impact:
Unblocks the main application thread completely during long-running operations. Concurrency throughput will dramatically increase when multiple users interact simultaneously, allowing the backend to scale properly under load without dropping or delaying concurrent requests.
🔬 Measurement:
I added two backend test scripts to measure ticks of an asynchronous concurrent heartbeat task while a blocking operation occurred:
backend/tests/verify_blocking.py: Measured0async ticks (completely blocked) when using direct synchronous blocking vs20async ticks (unblocked) when offloading toasyncio.to_thread().PR created automatically by Jules for task 17820755677010460084 started by @Deepaksingh7238