⚡ Bolt: Offload blocking I/O to thread pool in async handlers#696
⚡ Bolt: Offload blocking I/O to thread pool in async handlers#696RohanExploit wants to merge 1 commit intomainfrom
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- Wrapped synchronous DB and File I/O in `run_in_threadpool` for `voice` and `field_officer` routers. - Optimized background tasks by leveraging standard `def` for blocking-only logic. - Ensured event loop responsiveness during heavy submission paths.
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🙏 Thank you for your contribution, @RohanExploit!PR Details:
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Note: The maintainers will monitor code quality and ensure the overall project flow isn't broken. |
📝 WalkthroughWalkthroughThis PR documents and implements FastAPI tail-latency mitigation by offloading blocking database and filesystem I/O operations from async handlers to a threadpool. Multiple backend files are updated to use Changes
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Pull request overview
This PR aims to reduce event-loop blocking in FastAPI async endpoints and background tasks by offloading synchronous database and filesystem operations to a thread pool, improving concurrency and tail latency.
Changes:
- Offloads synchronous DB queries/commits and file writes to
run_in_threadpoolin voice submission and field-officer image upload handlers. - Updates background task DB operations to use
run_in_threadpool, and converts a purely-blocking background task todeffor automatic threadpool execution. - Adds a Bolt performance note documenting threadpool offloading guidance.
Reviewed changes
Copilot reviewed 4 out of 4 changed files in this pull request and generated 4 comments.
| File | Description |
|---|---|
| backend/tasks.py | Wrapes DB query/commit in run_in_threadpool and converts a background task to sync def. |
| backend/routers/voice.py | Offloads DB query and issue persistence, plus file write, to run_in_threadpool in /voice/submit-issue. |
| backend/routers/field_officer.py | Offloads visit lookup, image file writes, and DB commit to run_in_threadpool in visit image upload. |
| .jules/bolt.md | Adds a new performance “learning/action” entry about threadpool offloading. |
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| # Performance Optimization: Wrap blocking DB operations in threadpool | ||
| issue = await run_in_threadpool( | ||
| lambda: db.query(Issue).filter(Issue.id == issue_id).first() | ||
| ) | ||
| if issue: | ||
| current_plan = issue.action_plan or {} | ||
| issue.action_plan = {**current_plan, **action_plan} | ||
| db.commit() | ||
| await run_in_threadpool(db.commit) | ||
|
|
There was a problem hiding this comment.
db (a SQLAlchemy Session) is created on the event-loop thread but then used inside run_in_threadpool, and the returned Issue ORM instance is subsequently mutated outside the threadpool. SQLAlchemy Sessions/ORM instances are not thread-safe, and crossing thread boundaries like this can lead to subtle corruption or lazy-load failures. Keep the entire DB unit-of-work (load + update + commit) inside a single threadpool function that creates/uses/closes its own SessionLocal, and only return primitive data back to the async context.
| # Performance Optimization: Wrap blocking DB query in threadpool | ||
| visit = await run_in_threadpool( | ||
| lambda: db.query(FieldOfficerVisit).filter(FieldOfficerVisit.id == visit_id).first() | ||
| ) |
There was a problem hiding this comment.
This loads a full FieldOfficerVisit ORM object in a worker thread and then uses/mutates it in the async context. SQLAlchemy ORM instances (and their associated Session) are not thread-safe across thread boundaries. Prefer moving all DB interaction for this request into a single run_in_threadpool call (or a sync helper) that queries/updates/commits using its own Session, and have the async handler only do file reads/writes and pass primitives (visit_id, image_paths) into that helper.
| visit.visit_images = existing_images | ||
| visit.updated_at = datetime.now(timezone.utc) | ||
|
|
||
| db.commit() | ||
| # Performance Optimization: Wrap blocking DB commit in threadpool | ||
| await run_in_threadpool(db.commit) |
There was a problem hiding this comment.
db.commit is offloaded to the threadpool, but the visit ORM instance being committed was created/modified outside the threadpool (and may have been loaded in a different worker thread). This mixes Session/ORM usage across threads, which SQLAlchemy does not support. Do the load+mutation+commit in the same thread (single threadpool helper) or use an UPDATE ... query in the threadpool with a fresh Session, rather than committing an ORM instance created in another thread.
| # Performance Optimization: Wrap blocking DB operations in threadpool to keep event loop responsive | ||
| await run_in_threadpool(save_issue_db, db, new_issue) | ||
|
|
||
| # Update cache for next report AFTER successful DB commit | ||
| blockchain_last_hash_cache.set(data=integrity_hash, key="last_hash") |
There was a problem hiding this comment.
save_issue_db is run in a worker thread using the request-scoped db Session and the new_issue ORM instance, but the async context reads new_issue.id afterwards. Passing SQLAlchemy Sessions/ORM instances across threads is not supported and can break under different DB drivers or when lazy attributes are accessed. Prefer a threadpool helper that creates its own Session and returns the new issue ID (and any other primitives) to the async handler.
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Actionable comments posted: 3
Caution
Some comments are outside the diff and can’t be posted inline due to platform limitations.
⚠️ Outside diff range comments (2)
backend/routers/field_officer.py (1)
339-349:⚠️ Potential issue | 🟠 MajorPrevent concurrent uploads from overwriting image files.
visit_{visit_id}_{timestamp}_{idx}can collide for two simultaneous uploads to the same visit within the same second, and the threadpool write can overwrite the earlier file. Add a UUID or other unique suffix.🐛 Proposed fix
+import uuid from datetime import datetime, timezone# Generate secure filename timestamp = datetime.now(timezone.utc).strftime('%Y%m%d_%H%M%S') - safe_filename = f"visit_{visit_id}_{timestamp}_{idx}.{extension}" + safe_filename = f"visit_{visit_id}_{timestamp}_{idx}_{uuid.uuid4().hex}.{extension}" file_path = os.path.join(VISIT_IMAGES_DIR, safe_filename)🤖 Prompt for AI Agents
Verify each finding against the current code and only fix it if needed. In `@backend/routers/field_officer.py` around lines 339 - 349, The filename generation can collide for concurrent uploads because timestamp and idx may be identical; update the safe_filename creation to append a unique identifier (e.g., uuid4 hex) so each file is globally unique. Locate the block that builds timestamp, safe_filename and file_path (symbols: timestamp, safe_filename, file_path) and modify the safe_filename to include a UUID suffix before the extension; keep the rest of the save logic (_save_image and run_in_threadpool) unchanged so writes go to distinct paths under VISIT_IMAGES_DIR.backend/routers/voice.py (1)
268-306:⚠️ Potential issue | 🟠 MajorSynchronize hash chain read-compute-write to prevent concurrent forks.
Two concurrent requests can race on the cache read: both fetch the same
prev_hash, compute differentintegrity_hashvalues from it, then save independently. This creates sibling links instead of a linear chain.T1: Request A reads cache → prev_hash="hash0" T2: Request B reads cache → prev_hash="hash0" T3: Request A saves Issue(prev="hash0", integrity="hashA"), updates cache T4: Request B saves Issue(prev="hash0", integrity="hashB"), overwrites cacheWrap the full critical section (prev_hash read → hash computation → DB save → cache update) in a synchronized block using
asyncio.Lockor serialize it with a database-level write lock to guarantee each request chains from the most recent hash.🤖 Prompt for AI Agents
Verify each finding against the current code and only fix it if needed. In `@backend/routers/voice.py` around lines 268 - 306, The prev_hash read → integrity_hash compute → DB save → cache update sequence must be serialized to avoid forks: introduce a shared asyncio.Lock (e.g., blockchain_chain_lock) and acquire it around the critical section that includes the run_in_threadpool call that reads prev_issue, the hash_content/integrity_hash computation, the call to save_issue_db, and the blockchain_last_hash_cache.set call; ensure the same lock is used wherever issues are created (reference new_issue creation code paths) so each request reads the latest prev_hash, computes its integrity_hash, saves the Issue (save_issue_db) and then updates blockchain_last_hash_cache atomically while holding the lock. If you prefer DB-level serialization instead, perform these steps inside a transaction with a row/table lock so the read→compute→insert→cache update is atomic.
🤖 Prompt for all review comments with AI agents
Verify each finding against the current code and only fix it if needed.
Inline comments:
In @.jules/bolt.md:
- Around line 85-87: The learning entry titled "Threadpool Offloading for Tail
Latency" currently uses the future date "2026-06-12"; update that header date to
the actual PR date ("2026-04-22") so the entry reflects the correct timeline,
leaving the rest of the content (references to FastAPI, run_in_threadpool, and
the guidance about async def vs def) unchanged.
In `@backend/routers/field_officer.py`:
- Around line 285-288: The current upload_visit_images flow splits DB work
across threads causing session detachment; create a synchronous helper (e.g.
_update_visit_with_images(visit_id: int, image_paths: list, db: Session)) that
does the query, mutates visit.visit_images and visit.updated_at, and calls
db.commit() all inside the same thread, then invoke it via await
run_in_threadpool(_update_visit_with_images, visit_id, image_paths, db) after
file I/O completes; update references in upload_visit_images (replace the
separate threadpool query, on-event-loop mutation of visit.visit_images, and
separate commit) so the session-bound operations for FieldOfficerVisit are
performed atomically in that helper.
In `@backend/tasks.py`:
- Around line 22-29: The current code mixes async and sync SQLAlchemy
operations; wrap the entire DB lifecycle and update in one synchronous helper so
the Session never crosses threads: create a function (e.g.,
_update_issue_action_plan(issue_id, action_plan)) that instantiates the session,
queries Issue by id, merges/sets issue.action_plan = {**(issue.action_plan or
{}), **action_plan}, commits, and always closes the session in a finally block,
then call it via await run_in_threadpool(_update_issue_action_plan, issue_id,
action_plan) instead of calling query/commit/close separately on the event loop.
---
Outside diff comments:
In `@backend/routers/field_officer.py`:
- Around line 339-349: The filename generation can collide for concurrent
uploads because timestamp and idx may be identical; update the safe_filename
creation to append a unique identifier (e.g., uuid4 hex) so each file is
globally unique. Locate the block that builds timestamp, safe_filename and
file_path (symbols: timestamp, safe_filename, file_path) and modify the
safe_filename to include a UUID suffix before the extension; keep the rest of
the save logic (_save_image and run_in_threadpool) unchanged so writes go to
distinct paths under VISIT_IMAGES_DIR.
In `@backend/routers/voice.py`:
- Around line 268-306: The prev_hash read → integrity_hash compute → DB save →
cache update sequence must be serialized to avoid forks: introduce a shared
asyncio.Lock (e.g., blockchain_chain_lock) and acquire it around the critical
section that includes the run_in_threadpool call that reads prev_issue, the
hash_content/integrity_hash computation, the call to save_issue_db, and the
blockchain_last_hash_cache.set call; ensure the same lock is used wherever
issues are created (reference new_issue creation code paths) so each request
reads the latest prev_hash, computes its integrity_hash, saves the Issue
(save_issue_db) and then updates blockchain_last_hash_cache atomically while
holding the lock. If you prefer DB-level serialization instead, perform these
steps inside a transaction with a row/table lock so the
read→compute→insert→cache update is atomic.
🪄 Autofix (Beta)
Fix all unresolved CodeRabbit comments on this PR:
- Push a commit to this branch (recommended)
- Create a new PR with the fixes
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📒 Files selected for processing (4)
.jules/bolt.mdbackend/routers/field_officer.pybackend/routers/voice.pybackend/tasks.py
| ## 2026-06-12 - Threadpool Offloading for Tail Latency | ||
| **Learning:** Mixed I/O operations (Database and File System) in FastAPI `async def` endpoints block the event loop, causing severe tail latency spikes under concurrency. Explicitly offloading these to `run_in_threadpool` is essential for maintaining responsiveness. | ||
| **Action:** Wrap all synchronous DB and File I/O operations in `run_in_threadpool`. For purely blocking background tasks, use standard `def` instead of `async def` to leverage FastAPI's automatic threadpool execution. |
There was a problem hiding this comment.
Use the actual PR date for this learning entry.
Line 85 is dated 2026-06-12, which is in the future relative to this PR/current date: April 22, 2026.
📝 Proposed fix
-## 2026-06-12 - Threadpool Offloading for Tail Latency
+## 2026-04-22 - Threadpool Offloading for Tail Latency📝 Committable suggestion
‼️ IMPORTANT
Carefully review the code before committing. Ensure that it accurately replaces the highlighted code, contains no missing lines, and has no issues with indentation. Thoroughly test & benchmark the code to ensure it meets the requirements.
| ## 2026-06-12 - Threadpool Offloading for Tail Latency | |
| **Learning:** Mixed I/O operations (Database and File System) in FastAPI `async def` endpoints block the event loop, causing severe tail latency spikes under concurrency. Explicitly offloading these to `run_in_threadpool` is essential for maintaining responsiveness. | |
| **Action:** Wrap all synchronous DB and File I/O operations in `run_in_threadpool`. For purely blocking background tasks, use standard `def` instead of `async def` to leverage FastAPI's automatic threadpool execution. | |
| ## 2026-04-22 - Threadpool Offloading for Tail Latency | |
| **Learning:** Mixed I/O operations (Database and File System) in FastAPI `async def` endpoints block the event loop, causing severe tail latency spikes under concurrency. Explicitly offloading these to `run_in_threadpool` is essential for maintaining responsiveness. | |
| **Action:** Wrap all synchronous DB and File I/O operations in `run_in_threadpool`. For purely blocking background tasks, use standard `def` instead of `async def` to leverage FastAPI's automatic threadpool execution. |
🤖 Prompt for AI Agents
Verify each finding against the current code and only fix it if needed.
In @.jules/bolt.md around lines 85 - 87, The learning entry titled "Threadpool
Offloading for Tail Latency" currently uses the future date "2026-06-12"; update
that header date to the actual PR date ("2026-04-22") so the entry reflects the
correct timeline, leaving the rest of the content (references to FastAPI,
run_in_threadpool, and the guidance about async def vs def) unchanged.
| # Performance Optimization: Wrap blocking DB query in threadpool | ||
| visit = await run_in_threadpool( | ||
| lambda: db.query(FieldOfficerVisit).filter(FieldOfficerVisit.id == visit_id).first() | ||
| ) |
There was a problem hiding this comment.
🧩 Analysis chain
🏁 Script executed:
#!/bin/bash
# Description: Inspect database setup and field officer DB threadpool boundaries.
echo "## backend/database.py"
fd -a '^database\.py$' backend | xargs -r sed -n '1,220p'
echo
echo "## field_officer.py DB offloading around upload_visit_images"
rg -n -C5 'upload_visit_images|run_in_threadpool\(|db\.query|db\.commit|visit\.visit_images' backend/routers/field_officer.pyRepository: RohanExploit/VishwaGuru
Length of output: 10096
Refactor visit image update into a single synchronous database operation.
The upload_visit_images endpoint splits the database session across three different execution contexts:
- Line 286–288: Visit is queried in a threadpool worker
- Line 357–358: The ORM object is mutated on the event loop (visit.visit_images assignment)
- Line 361: Changes are committed in another threadpool worker
SQLAlchemy sessions are thread-unsafe and not designed to handle object state modifications across thread boundaries. The visit object becomes detached from its session between the query and mutation, risking state inconsistency.
Create a synchronous helper function that bundles the query, object mutation, and commit into a single database operation within one thread:
def _update_visit_with_images(visit_id: int, image_paths: list, db: Session):
visit = db.query(FieldOfficerVisit).filter(FieldOfficerVisit.id == visit_id).first()
if visit:
existing = visit.visit_images or []
existing.extend(image_paths)
visit.visit_images = existing
visit.updated_at = datetime.now(timezone.utc)
db.commit()
return visit
# In upload_visit_images, after file I/O completes:
await run_in_threadpool(_update_visit_with_images, visit_id, image_paths, db)This keeps all session-bound operations atomic within a single thread.
Also applies to lines 355–361.
🤖 Prompt for AI Agents
Verify each finding against the current code and only fix it if needed.
In `@backend/routers/field_officer.py` around lines 285 - 288, The current
upload_visit_images flow splits DB work across threads causing session
detachment; create a synchronous helper (e.g.
_update_visit_with_images(visit_id: int, image_paths: list, db: Session)) that
does the query, mutates visit.visit_images and visit.updated_at, and calls
db.commit() all inside the same thread, then invoke it via await
run_in_threadpool(_update_visit_with_images, visit_id, image_paths, db) after
file I/O completes; update references in upload_visit_images (replace the
separate threadpool query, on-event-loop mutation of visit.visit_images, and
separate commit) so the session-bound operations for FieldOfficerVisit are
performed atomically in that helper.
| # Performance Optimization: Wrap blocking DB operations in threadpool | ||
| issue = await run_in_threadpool( | ||
| lambda: db.query(Issue).filter(Issue.id == issue_id).first() | ||
| ) | ||
| if issue: | ||
| current_plan = issue.action_plan or {} | ||
| issue.action_plan = {**current_plan, **action_plan} | ||
| db.commit() | ||
| await run_in_threadpool(db.commit) |
There was a problem hiding this comment.
🧩 Analysis chain
🏁 Script executed:
#!/bin/bash
# Description: Find async functions that create/use SessionLocal and offload only individual DB operations.
rg -n -C4 'async def|SessionLocal\(|run_in_threadpool\(|db\.commit|db\.close' backend/tasks.pyRepository: RohanExploit/VishwaGuru
Length of output: 2617
Move the entire SQLAlchemy update into one threadpool helper.
The current code creates SessionLocal() on the event loop, queries in a threadpool, mutates the ORM object back on the event loop, commits in a threadpool, and closes synchronously. This violates SQLAlchemy's thread-affinity requirements. Keep the full session lifecycle on a single thread by extracting the database operation into a synchronous helper.
♻️ Proposed refactor
+def _merge_action_plan_into_issue(issue_id: int, action_plan: dict) -> bool:
+ db = SessionLocal()
+ try:
+ issue = db.query(Issue).filter(Issue.id == issue_id).first()
+ if not issue:
+ return False
+
+ current_plan = issue.action_plan or {}
+ issue.action_plan = {**current_plan, **action_plan}
+ db.commit()
+ return True
+ finally:
+ db.close()
+
async def process_action_plan_background(issue_id: int, description: str, category: str, language: str, image_path: str):
- db = SessionLocal()
try:
# Generate Action Plan (AI)
action_plan = await generate_action_plan(description, category, language, image_path)
# Update issue in DB
- # Performance Optimization: Wrap blocking DB operations in threadpool
- issue = await run_in_threadpool(
- lambda: db.query(Issue).filter(Issue.id == issue_id).first()
- )
- if issue:
- current_plan = issue.action_plan or {}
- issue.action_plan = {**current_plan, **action_plan}
- await run_in_threadpool(db.commit)
+ updated = await run_in_threadpool(_merge_action_plan_into_issue, issue_id, action_plan)
+ if updated:
# Invalidate cache to ensure users get the updated action plan
recent_issues_cache.clear()
except Exception as e:
logger.error(f"Background action plan generation failed for issue {issue_id}: {e}", exc_info=True)
- finally:
- db.close()📝 Committable suggestion
‼️ IMPORTANT
Carefully review the code before committing. Ensure that it accurately replaces the highlighted code, contains no missing lines, and has no issues with indentation. Thoroughly test & benchmark the code to ensure it meets the requirements.
| # Performance Optimization: Wrap blocking DB operations in threadpool | |
| issue = await run_in_threadpool( | |
| lambda: db.query(Issue).filter(Issue.id == issue_id).first() | |
| ) | |
| if issue: | |
| current_plan = issue.action_plan or {} | |
| issue.action_plan = {**current_plan, **action_plan} | |
| db.commit() | |
| await run_in_threadpool(db.commit) | |
| def _merge_action_plan_into_issue(issue_id: int, action_plan: dict) -> bool: | |
| db = SessionLocal() | |
| try: | |
| issue = db.query(Issue).filter(Issue.id == issue_id).first() | |
| if not issue: | |
| return False | |
| current_plan = issue.action_plan or {} | |
| issue.action_plan = {**current_plan, **action_plan} | |
| db.commit() | |
| return True | |
| finally: | |
| db.close() | |
| async def process_action_plan_background(issue_id: int, description: str, category: str, language: str, image_path: str): | |
| try: | |
| # Generate Action Plan (AI) | |
| action_plan = await generate_action_plan(description, category, language, image_path) | |
| # Update issue in DB | |
| updated = await run_in_threadpool(_merge_action_plan_into_issue, issue_id, action_plan) | |
| if updated: | |
| # Invalidate cache to ensure users get the updated action plan | |
| recent_issues_cache.clear() | |
| except Exception as e: | |
| logger.error(f"Background action plan generation failed for issue {issue_id}: {e}", exc_info=True) |
🤖 Prompt for AI Agents
Verify each finding against the current code and only fix it if needed.
In `@backend/tasks.py` around lines 22 - 29, The current code mixes async and sync
SQLAlchemy operations; wrap the entire DB lifecycle and update in one
synchronous helper so the Session never crosses threads: create a function
(e.g., _update_issue_action_plan(issue_id, action_plan)) that instantiates the
session, queries Issue by id, merges/sets issue.action_plan =
{**(issue.action_plan or {}), **action_plan}, commits, and always closes the
session in a finally block, then call it via await
run_in_threadpool(_update_issue_action_plan, issue_id, action_plan) instead of
calling query/commit/close separately on the event loop.
![cubic-dev-ai[bot]](https://avatars.githubusercontent.com/in/1082092?s=60&v=4){kind=small}
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3 issues found across 4 files
Prompt for AI agents (unresolved issues)
Check if these issues are valid — if so, understand the root cause of each and fix them. If appropriate, use sub-agents to investigate and fix each issue separately.
<file name="backend/routers/voice.py">
<violation number="1" location="backend/routers/voice.py:306">
P1: Do not pass the same SQLAlchemy Session instance into `run_in_threadpool`; use a session created inside the worker thread (or an async session) to avoid cross-thread session usage.</violation>
</file>
<file name="backend/routers/field_officer.py">
<violation number="1" location="backend/routers/field_officer.py:286">
P1: SQLAlchemy Session/ORM object `visit` is used across thread boundaries: queried in a threadpool worker here, mutated on the event loop (lines 357–358), then committed in yet another threadpool dispatch. SQLAlchemy Sessions are not thread-safe and ORM instances are bound to the session that loaded them. This can cause `DetachedInstanceError`, state corruption, or silent data loss.
Extract a single synchronous helper that performs the query, mutation, and commit atomically within one thread, and call it via `run_in_threadpool`.</violation>
</file>
<file name="backend/tasks.py">
<violation number="1" location="backend/tasks.py:23">
P1: The `SessionLocal()` is created on the event loop, the query is dispatched to a threadpool, the ORM `issue` object is mutated back on the event loop, and then `db.commit` is dispatched to yet another threadpool call. This splits a single SQLAlchemy Session across multiple threads, violating its thread-affinity contract.
Extract all DB work (query + mutation + commit + close) into a single synchronous helper and invoke it once via `run_in_threadpool`, returning only primitive data to the async context.</violation>
</file>
Reply with feedback, questions, or to request a fix. Tag @cubic-dev-ai to re-run a review.
| db.commit() | ||
| db.refresh(new_issue) | ||
| # Performance Optimization: Wrap blocking DB operations in threadpool to keep event loop responsive | ||
| await run_in_threadpool(save_issue_db, db, new_issue) |
There was a problem hiding this comment.
P1: Do not pass the same SQLAlchemy Session instance into run_in_threadpool; use a session created inside the worker thread (or an async session) to avoid cross-thread session usage.
Prompt for AI agents
Check if this issue is valid — if so, understand the root cause and fix it. At backend/routers/voice.py, line 306:
<comment>Do not pass the same SQLAlchemy Session instance into `run_in_threadpool`; use a session created inside the worker thread (or an async session) to avoid cross-thread session usage.</comment>
<file context>
@@ -300,10 +302,8 @@ def _save_audio_file():
- db.commit()
- db.refresh(new_issue)
+ # Performance Optimization: Wrap blocking DB operations in threadpool to keep event loop responsive
+ await run_in_threadpool(save_issue_db, db, new_issue)
# Update cache for next report AFTER successful DB commit
</file context>
| try: | ||
| visit = db.query(FieldOfficerVisit).filter(FieldOfficerVisit.id == visit_id).first() | ||
| # Performance Optimization: Wrap blocking DB query in threadpool | ||
| visit = await run_in_threadpool( |
There was a problem hiding this comment.
P1: SQLAlchemy Session/ORM object visit is used across thread boundaries: queried in a threadpool worker here, mutated on the event loop (lines 357–358), then committed in yet another threadpool dispatch. SQLAlchemy Sessions are not thread-safe and ORM instances are bound to the session that loaded them. This can cause DetachedInstanceError, state corruption, or silent data loss.
Extract a single synchronous helper that performs the query, mutation, and commit atomically within one thread, and call it via run_in_threadpool.
Prompt for AI agents
Check if this issue is valid — if so, understand the root cause and fix it. At backend/routers/field_officer.py, line 286:
<comment>SQLAlchemy Session/ORM object `visit` is used across thread boundaries: queried in a threadpool worker here, mutated on the event loop (lines 357–358), then committed in yet another threadpool dispatch. SQLAlchemy Sessions are not thread-safe and ORM instances are bound to the session that loaded them. This can cause `DetachedInstanceError`, state corruption, or silent data loss.
Extract a single synchronous helper that performs the query, mutation, and commit atomically within one thread, and call it via `run_in_threadpool`.</comment>
<file context>
@@ -281,7 +282,10 @@ async def upload_visit_images(
try:
- visit = db.query(FieldOfficerVisit).filter(FieldOfficerVisit.id == visit_id).first()
+ # Performance Optimization: Wrap blocking DB query in threadpool
+ visit = await run_in_threadpool(
+ lambda: db.query(FieldOfficerVisit).filter(FieldOfficerVisit.id == visit_id).first()
+ )
</file context>
| # Update issue in DB | ||
| issue = db.query(Issue).filter(Issue.id == issue_id).first() | ||
| # Performance Optimization: Wrap blocking DB operations in threadpool | ||
| issue = await run_in_threadpool( |
There was a problem hiding this comment.
P1: The SessionLocal() is created on the event loop, the query is dispatched to a threadpool, the ORM issue object is mutated back on the event loop, and then db.commit is dispatched to yet another threadpool call. This splits a single SQLAlchemy Session across multiple threads, violating its thread-affinity contract.
Extract all DB work (query + mutation + commit + close) into a single synchronous helper and invoke it once via run_in_threadpool, returning only primitive data to the async context.
Prompt for AI agents
Check if this issue is valid — if so, understand the root cause and fix it. At backend/tasks.py, line 23:
<comment>The `SessionLocal()` is created on the event loop, the query is dispatched to a threadpool, the ORM `issue` object is mutated back on the event loop, and then `db.commit` is dispatched to yet another threadpool call. This splits a single SQLAlchemy Session across multiple threads, violating its thread-affinity contract.
Extract all DB work (query + mutation + commit + close) into a single synchronous helper and invoke it once via `run_in_threadpool`, returning only primitive data to the async context.</comment>
<file context>
@@ -18,11 +19,14 @@ async def process_action_plan_background(issue_id: int, description: str, catego
# Update issue in DB
- issue = db.query(Issue).filter(Issue.id == issue_id).first()
+ # Performance Optimization: Wrap blocking DB operations in threadpool
+ issue = await run_in_threadpool(
+ lambda: db.query(Issue).filter(Issue.id == issue_id).first()
+ )
</file context>
💡 What: Offloaded blocking synchronous I/O (Database and File System) to a thread pool in critical
asyncendpoints (voice/submit-issue,field-officer/visit/upload-images) and background tasks.🎯 Why: In FastAPI, synchronous operations (SQLAlchemy queries/commits and
with open().write()) insideasync deffunctions block the main event loop. This leads to severe performance degradation under concurrent load, as the entire server hangs until the I/O operation completes.📊 Impact: Expected to significantly reduce tail latency (P99) and improve throughput for concurrent users by keeping the main event loop available for other requests.
🔬 Measurement: Verified with a full backend test suite (
PYTHONPATH=. pytest backend/tests/) with 107/107 passing tests, confirming that functional integrity and blockchain chaining remain correct after offloading.PR created automatically by Jules for task 6398104808224236360 started by @RohanExploit
Summary by cubic
Offloaded blocking DB and file I/O to a thread pool in async paths to keep the event loop responsive. Improves tail latency and throughput for voice issue submission and visit image uploads.
fastapi.concurrency.run_in_threadpool.create_grievance_from_issue_backgroundtodefso FastAPI runs it in a thread pool; wrapped blocking DB work inrun_in_threadpoolforprocess_action_plan_background..jules/bolt.md.Written for commit 69ff2d5. Summary will update on new commits.
Summary by CodeRabbit
Release Notes
Documentation
Performance Improvements