fix: resolve potential deadlock in AsyncInMemoryCache

[dhlidongming]

This pull request resolves potential concurrency issues in the AsyncInMemoryCache class.

In the upsert function:

langflow/src/backend/base/langflow/services/cache/service.py

Lines 357 to 360 in 1e4594a

	async def upsert(self, key, value, lock: asyncio.Lock | None = None) -> None:
	if not lock:
	async with self.lock:
	await self._upsert(key, value)

if the lock parameter is not provided, the self.lock object is used to acquire a lock before calling the _upsert function. Within the _upsert function, the get function is invoked without a lock parameter:

langflow/src/backend/base/langflow/services/cache/service.py

Lines 364 to 365 in 1e4594a

	async def _upsert(self, key, value) -> None:
	existing_value = await self.get(key)

which causes the get function to acquire the self.lock object again, leading to a deadlock:

langflow/src/backend/base/langflow/services/cache/service.py

Lines 300 to 303 in 1e4594a

	async def get(self, key, lock: asyncio.Lock | None = None):
	if not lock:
	async with self.lock:
	return await self._get(key)

[dhlidongming]

@ogabrielluiz The PR contains an error: the lock parameter cannot be removed, even though it is not used.
Because the base class abstract method includes this parameter:

langflow/src/backend/base/langflow/services/cache/base.py

Line 40 in 0bf7dda

def upsert(self, key, value, lock: LockType | None = None):

It will also be passed in during the call.

[ogabrielluiz]

@ogabrielluiz The PR contains an error: the lock parameter cannot be removed, even though it is not used. Because the base class abstract method includes this parameter:

langflow/src/backend/base/langflow/services/cache/base.py

Line 40 in 0bf7dda

def upsert(self, key, value, lock: LockType | None = None):

It will also be passed in during the call.

Hey @dhlidongming

Thanks for this fix.

Maybe you could pass the lock all the way down to the get method.

[cbornet]

Could also use a rentrant lock asyncio.RLock ?

[cbornet]

Annotate the method with @override (from typing_extensions) to solve the ARG002 rule error.

[codspeed-hq]

CodSpeed Performance Report

Merging #4464 will degrade performances by 15.55%

_{Comparing dhlidongming:fix/async-memory-cache-lock-issues (8279837) with main (0f5c31f)}

Summary

⚡ 2 improvements
❌ 1 regressions
✅ 12 untouched benchmarks

⚠️ Please fix the performance issues or acknowledge them on CodSpeed.

Benchmarks breakdown

	Benchmark	main	dhlidongming:fix/async-memory-cache-lock-issues	Change
⚡	test_get_all	5,192.8 ms	520.5 ms	×10
❌	test_invalid_run_with_input_type_chat	13.8 ms	16.4 ms	-15.55%
⚡	test_successful_run_with_input_type_text	172.3 ms	141.6 ms	+21.7%

[ogabrielluiz]

LGTM