PGVector / Postgres connection is not automatically closed, and remains idle

[Lengo46]

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

from datetime import datetime
from langchain_postgres import PGVector
from langchain_openai import OpenAIEmbeddings
from dotenv import load_dotenv

load_dotenv()

connection = os.getenv('POSTGRES_CONNECTION_STRING')  
embeddings = OpenAIEmbeddings(model="text-embedding-ada-002")

async def vectorStore(pg_table_name: str, remove = False):
    return PGVector(
        embeddings=embeddings,
        collection_name=pg_table_name,
        connection=connection,
        use_jsonb=True,
        pre_delete_collection=remove,
    )

### Error Message and Stack Trace (if applicable)

`psql: FATAL: remaining connection slots are reserved for non-replication superuser connections`

If I query the database, it's clearly that all connections remain idle and open.



### Description

This is a bug that was fixed in the past, see https://github.com/langchain-ai/langchain/issues/9696.  The PG Vector file has move to an import to  lanchain_postgres somewhere in the last year, which doesn't contain the fix for this issue.



### System Info

System Information
------------------
> OS:  Darwin
> OS Version:  Darwin Kernel Version 24.1.0: Thu Oct 10 21:03:15 PDT 2024; root:xnu-11215.41.3~2/RELEASE_ARM64_T6000
> Python Version:  3.11.1 (main, Jan  4 2023, 15:58:50) [Clang 14.0.0 (clang-1400.0.29.202)]

Package Information
-------------------
> langchain_core: 0.3.21
> langchain: 0.3.9
> langchain_community: 0.3.8
> langsmith: 0.1.135
> langchain_ollama: 0.2.0
> langchain_openai: 0.2.2
> langchain_postgres: 0.0.12
> langchain_text_splitters: 0.3.0

Optional packages not installed
-------------------------------
> langserve

Other Dependencies
------------------
> aiohttp: 3.10.10
> async-timeout: 4.0.3
> dataclasses-json: 0.6.7
> httpx: 0.27.2
> httpx-sse: 0.4.0
> jsonpatch: 1.33
> numpy: 1.26.4
> ollama: 0.3.3
> openai: 1.51.2
> orjson: 3.10.7
> packaging: 24.1
> pgvector: 0.2.5
> psycopg: 3.2.3
> psycopg-pool: 3.2.3
> pydantic: 2.10.4
> pydantic-settings: 2.5.2
> PyYAML: 6.0.2
> requests: 2.32.3
> requests-toolbelt: 1.0.0
> SQLAlchemy: 2.0.35
> sqlalchemy: 2.0.35
> tenacity: 8.5.0
> tiktoken: 0.8.0
> typing-extensions: 4.12.2