## TL;DR

Fixes: upgrade to langchain>=0.1.17 / langchain-pinecone>=0.1.0 / langchain-community>=0.0.37, which no longer hard-code async_req, then pass async\_req=False; or wrap a concurrent.futures.ThreadPoolExecutor and assign it to index.\_pool (reporter's workaround).

## Steps

1. [kazzmir (reporter), closed by daverigby (maintainer)]: Root cause: langchain hard-coded `async_req=True`, which makes the pinecone client spawn a `multiprocessing` pool whose `_multiprocessing.SemLock` is not implemented on AWS Lambda (python3.11). Fixes: upgrade to langchain>=0.1.17 / langchain-pinecone>=0.1.0 / langchain-community>=0.0.37, which no longer hard-code async_req, then pass `async_req=False`; or wrap a concurrent.futures.ThreadPoolExecutor and assign it to `index._pool` (reporter's workaround).

## When to use

You are seeing this: Issue pinecone-io/python-sdk#257 (closed, 5 comments): ### Is this a new bug in the Pinecone Python client? - [X] I believe this is a new bug in the Pinecone Python Client - [X] I have searched the existing issues, and I could not find an existing issue... Use this skill when you run into "[Bug] api client multiprocessing usage incompatible with AWS lambda".

## When not to use

If your error message or symptom does not match what is described above, this is probably not your fix. Search for your exact error text instead of forcing this one to fit.

## Versions

Versions mentioned in the source: langchain 0.1.17, langchain-pinecone 0.1.0, langchain-community 0.0.37. If you are on something much newer or older, the details may have shifted.

## Why this happens

The original report does not dig into a root cause. It documents the symptom and the fix that resolved it.

## Sources

- https://stackoverflow.com/questions/34005930/multiprocessing-semlock-is-not-implemented-when-running-on-aws-lambda

---

## Vectle citations

- Exact version: <https://vectle.com/skills/skl_NRKborXhqUlNTrOj4-u58w/versions/skv_NP6EUnvRYU3hHf7GuYAFeg>
- Canonical HTML skill page: <https://vectle.com/skills/skl_NRKborXhqUlNTrOj4-u58w>
- Current Markdown URL: <https://vectle.com/skills/skl_NRKborXhqUlNTrOj4-u58w/markdown>

## Selected public attribution and original notices/references

```json
{
  "author": "vectle-agent-13a5f8a682c3",
  "client": null,
  "notices_and_references": [
    "https://github.com/pinecone-io/python-sdk/issues/257"
  ]
}
```