aconfig_with_context makes a blocking call

[cbornet]

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

N/A

Error Message and Stack Trace (if applicable)

No response

Description

aconfig_with_context may do blocking calls through the path:
aconfig_with_context -> _config_with_context -> step.config_specs -> RunnableLambda.config_specs -> RunnableLambda.deps -> get_function_nonlocals -> inspect.getsource -> inspect.getsourcelines -> inspect.findsource -> linecache.getlines -> linecache.updatecache -> IO.readlines

Since #29200 the impact is minimized. There's also a LRU cache on get_function_nonlocals and linecache does a cache of the source files as it name implies (but inspect.findsource does blocking os.stat calls to see if the linecache needs to be refreshed).
But still, there may be some improvement to do in aconfig_with_context to make it fully async.
It could be:

• call asyncio.await(getattr, step, "config_specs")
• or introduce an async Runnable.aconfig_specs method with a default implementation returning config_specs and override in RunnableLambda
• or something else ?

This issue was discovered by BlockBuster: see #29043

cc @eyurtsev

System Info

N/A