Blocking sync code is used when using rate limiting in async code

[esciara]

Checked other resources

• I added a very descriptive title to this issue.
• I searched the LangChain documentation with the integrated search.
• I used the GitHub search to find a similar question and didn't find it.
• I am sure that this is a bug in LangChain rather than my code.
• The bug is not resolved by updating to the latest stable version of LangChain (or the specific integration package).

Example Code

Not applicable as current code runs but is blocked by non async code.

Error Message and Stack Trace (if applicable)

N/A

Description

Async code is using sync (blocking code) when using rate limiting in two places:

In BaseChatModel.astream():

langchain/libs/core/langchain_core/language_models/chat_models.py

Lines 465 to 466 in 02f5962

	if self.rate_limiter:
	self.rate_limiter.acquire(blocking=True)

In BaseChatModel._agenerate_with_cache():

langchain/libs/core/langchain_core/language_models/chat_models.py

Lines 907 to 908 in 02f5962

	if self.rate_limiter:
	self.rate_limiter.acquire(blocking=True)

System Info

System Information

OS: Darwin
OS Version: Darwin Kernel Version 23.6.0: Mon Jul 29 21:14:30 PDT 2024; root:xnu-10063.141.2~1/RELEASE_ARM64_T6000
Python Version: 3.12.2 (main, Feb 27 2024, 16:53:46) [Clang 15.0.0 (clang-1500.1.0.2.5)]

Package Information

langchain_core: 0.3.6
langchain: 0.3.1
langchain_community: 0.3.1
langsmith: 0.1.128
langchain_openai: 0.2.1
langchain_text_splitters: 0.3.0

Optional packages not installed

langgraph
langserve

Other Dependencies

aiohttp: 3.10.6
async-timeout: Installed. No version info available.
dataclasses-json: 0.6.7
httpx: 0.27.2
jsonpatch: 1.33
numpy: 1.26.4
openai: 1.48.0
orjson: 3.10.7
packaging: 24.1
pydantic: 2.9.2
pydantic-settings: 2.5.2
PyYAML: 6.0.2
requests: 2.32.3
SQLAlchemy: 2.0.35
tenacity: 8.5.0
tiktoken: 0.7.0
typing-extensions: 4.12.2

[eyurtsev]

Closing as this was fixed with your PR! thank you