async_utils

fastmcp.utilities.async_utils

Async utilities for FastMCP.

Functions

call_sync_fn_in_threadpool

call_sync_fn_in_threadpool(fn: Callable[..., Any], *args: Any, **kwargs: Any) -> Any

Call a sync function in a threadpool to avoid blocking the event loop.

Uses anyio.to_thread.run_sync which properly propagates contextvars, making this safe for functions that depend on context (like dependency injection).

gather

gather(*awaitables: Awaitable[T]) -> list[T] | list[T | BaseException]

Run awaitables concurrently and return results in order.

Uses anyio TaskGroup for structured concurrency.

Args:

• *awaitables: Awaitables to run concurrently
• return_exceptions: If True, exceptions are returned in results. If False, first exception cancels all and raises.

Returns:

• List of results in the same order as input awaitables.