[Bug]: Async operation is not working as expected for search in collection by using pymilvus

[V-N-Bhat]

Is there an existing issue for this?

• I have searched the existing issues

Describe the bug

I am trying to perform searching in the collection asynchronously and using pymilvus by passing _async as true along with a call back function it was running in the sync way instead of async . And tried to run the same collection.search. on different threads then also the database it self is running the search operation one by one .

Expected Behavior

The queries should run parallel or asynchronously.

Steps/Code To Reproduce behavior

def milvus_search(embedding_query):
    collection = Collection("bank")
    return collection.search(data=[embedding_query],
                                      anns_field="vector",
                                      param=search_params,
                                      limit=10,
                                      kwargs={"_async": True, "_callback": handle_result}
                                      )

async def search() -> SearchResult:
    embedding_function = HuggingFaceEmbeddings(model_name="sentence-transformers/all-MiniLM-L6-v2")
    embedding_query = embedding_function.embed_query("sso")
    search_future = await asyncio.to_thread(
        milvus_search,
        embedding_query
    )
return search_future


async def something() -> None:
    start =time.time()

    search_tasks = [search() for _ in range(2)]
    await asyncio.gather(*search_tasks)
    end = time.time()

    print(f"took{start - end} ")


if __name__ == "__main__":
    asyncio.run(something())

Environment details

- Hardware/Softward conditions (OS, CPU, GPU, Memory):
- Method of installation (Docker, or from source):
- Milvus version (v0.3.1, or v0.4.0):
- Milvus configuration (Settings you made in `server_config.yaml`):

Anything else?

No response