Add async support to client_factory in FastMCPProxy (#1286) #1375
Conversation
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
jlowin
requested changes
Aug 6, 2025
src/fastmcp/server/proxy.py
Outdated
|
|
||
| async def _get_client(self) -> Client: | ||
| """Gets a client instance by calling the sync or async factory.""" | ||
| if inspect.iscoroutinefunction(self.client_factory): |
There was a problem hiding this comment.
Minor nit - the pattern we prefer elsewhere is I think
client = self.client_factory()
if inspect.isawaitable(client):
client = await client
return clientThis way the factory can be any function that returns an awaitable (e.g. a sync-decorated coroutine, or a class).
There was a problem hiding this comment.
Updated _get_client to use the isawaitable pattern as suggested.
| client = cast(Client, proxy.client_factory()) | ||
| assert isinstance(client.transport, StreamableHttpTransport) | ||
| assert client.transport.url == "http://example.com/mcp/" # type: ignore[attr-defined] | ||
|
|
There was a problem hiding this comment.
Could you add a simple test to ensure that async factories are executed?
There was a problem hiding this comment.
Added a test for async factory usage as well.
added 2 commits
August 6, 2025 21:57
bianning
force-pushed
the
async_client_factory
branch
from
5ae06ff to
3189d96
Compare
jlowin
added
the
enhancement
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
2 participants
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
This adds async support for client_factory in FastMCPProxy.
Related Issue #1286
The change:
Accepts either a sync or async factory
Keeps existing sync behavior unchanged