---
title: async_utils
sidebarTitle: async_utils
---

# `fastmcp.utilities.async_utils`


Async utilities for FastMCP.

## Functions

### `is_coroutine_function` <sup><a href="https://github.com/PrefectHQ/fastmcp/blob/main/fastmcp_slim/fastmcp/utilities/async_utils.py#L14" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

```python
is_coroutine_function(fn: Any) -> bool
```


Check if a callable is a coroutine function, unwrapping functools.partial.

``inspect.iscoroutinefunction`` returns ``False`` for
``functools.partial`` objects wrapping an async function on Python < 3.12.
This helper unwraps any layers of ``partial`` before checking.


### `call_sync_fn_in_threadpool` <sup><a href="https://github.com/PrefectHQ/fastmcp/blob/main/fastmcp_slim/fastmcp/utilities/async_utils.py#L26" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

```python
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` <sup><a href="https://github.com/PrefectHQ/fastmcp/blob/main/fastmcp_slim/fastmcp/utilities/async_utils.py#L51" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

```python
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.

