modal.Function

class Function(typing.Generic, modal.object.Object)

Functions are the basic units of serverless execution on Modal.

Generally, you will not construct a Function directly. Instead, use the App.function() decorator to register your Python functions with your App.

def __init__(self, *args, **kwargs):

hydrate

def hydrate(self, client: Optional[_Client] = None) -> Self:

Synchronize the local object with its identity on the Modal server.

It is rarely necessary to call this method explicitly, as most operations will lazily hydrate when needed. The main use case is when you need to access object metadata, such as its ID.

Added in v0.72.39: This method replaces the deprecated .resolve() method.

keep_warm

@live_method
def keep_warm(self, warm_pool_size: int) -> None:

Set the warm pool size for the function.

Please exercise care when using this advanced feature! Setting and forgetting a warm pool on functions can lead to increased costs.

# Usage on a regular function.
f = modal.Function.from_name("my-app", "function")
f.keep_warm(2)

# Usage on a parametrized function.
Model = modal.Cls.from_name("my-app", "Model")
Model("fine-tuned-model").keep_warm(2)  # note that this applies to the class instance, not a method

from_name

@classmethod
@renamed_parameter((2024, 12, 18), "tag", "name")
def from_name(
    cls: type["_Function"],
    app_name: str,
    name: str,
    namespace=api_pb2.DEPLOYMENT_NAMESPACE_WORKSPACE,
    environment_name: Optional[str] = None,
) -> "_Function":

Reference a Function from a deployed App by its name.

In contrast to modal.Function.lookup, this is a lazy method that defers hydrating the local object with metadata from Modal servers until the first time it is actually used.

f = modal.Function.from_name("other-app", "function")

lookup

@staticmethod
@renamed_parameter((2024, 12, 18), "tag", "name")
def lookup(
    app_name: str,
    name: str,
    namespace=api_pb2.DEPLOYMENT_NAMESPACE_WORKSPACE,
    client: Optional[_Client] = None,
    environment_name: Optional[str] = None,
) -> "_Function":

Lookup a Function from a deployed App by its name.

DEPRECATED: This method is deprecated in favor of modal.Function.from_name.

In contrast to modal.Function.from_name, this is an eager method that will hydrate the local object with metadata from Modal servers.

f = modal.Function.lookup("other-app", "function")

web_url

@property
@live_method
def web_url(self) -> Optional[str]:

URL of a Function running as a web endpoint.

remote

@live_method
def remote(self, *args: P.args, **kwargs: P.kwargs) -> ReturnType:

Calls the function remotely, executing it with the given arguments and returning the execution’s result.

remote_gen

@live_method_gen
def remote_gen(self, *args, **kwargs) -> AsyncGenerator[Any, None]:

Calls the generator remotely, executing it with the given arguments and returning the execution’s result.

local

def local(self, *args: P.args, **kwargs: P.kwargs) -> OriginalReturnType:

Calls the function locally, executing it with the given arguments and returning the execution’s result.

The function will execute in the same environment as the caller, just like calling the underlying function directly in Python. In particular, only secrets available in the caller environment will be available through environment variables.

spawn

@live_method
def spawn(self, *args: P.args, **kwargs: P.kwargs) -> "_FunctionCall[ReturnType]":

Calls the function with the given arguments, without waiting for the results.

Returns a modal.FunctionCall object, that can later be polled or waited for using .get(timeout=...). Conceptually similar to multiprocessing.pool.apply_async, or a Future/Promise in other contexts.

get_raw_f

def get_raw_f(self) -> Callable[..., Any]:

Return the inner Python object wrapped by this Modal Function.

get_current_stats

@live_method
def get_current_stats(self) -> FunctionStats:

Return a FunctionStats object describing the current function’s queue and runner counts.

map

@warn_if_generator_is_not_consumed(function_name="Function.map")
def map(
    self,
    *input_iterators: typing.Iterable[Any],  # one input iterator per argument in the mapped-over function/generator
    kwargs={},  # any extra keyword arguments for the function
    order_outputs: bool = True,  # return outputs in order
    return_exceptions: bool = False,  # propagate exceptions (False) or aggregate them in the results list (True)
) -> AsyncOrSyncIterable:

Parallel map over a set of inputs.

Takes one iterator argument per argument in the function being mapped over.

Example:

@app.function()
def my_func(a):
    return a ** 2


@app.local_entrypoint()
def main():
    assert list(my_func.map([1, 2, 3, 4])) == [1, 4, 9, 16]

If applied to a stub.function, map() returns one result per input and the output order is guaranteed to be the same as the input order. Set order_outputs=False to return results in the order that they are completed instead.

return_exceptions can be used to treat exceptions as successful results:

@app.function()
def my_func(a):
    if a == 2:
        raise Exception("ohno")
    return a ** 2


@app.local_entrypoint()
def main():
    # [0, 1, UserCodeException(Exception('ohno'))]
    print(list(my_func.map(range(3), return_exceptions=True)))

starmap

@warn_if_generator_is_not_consumed(function_name="Function.starmap.aio")
def starmap(
    self,
    input_iterator: typing.Iterable[typing.Sequence[Any]],
    kwargs={},
    order_outputs: bool = True,
    return_exceptions: bool = False,
) -> AsyncOrSyncIterable:

Like map, but spreads arguments over multiple function arguments.

Assumes every input is a sequence (e.g. a tuple).

Example:

@app.function()
def my_func(a, b):
    return a + b


@app.local_entrypoint()
def main():
    assert list(my_func.starmap([(1, 2), (3, 4)])) == [3, 7]

for_each

def for_each(self, *input_iterators, kwargs={}, ignore_exceptions: bool = False):

Execute function for all inputs, ignoring outputs.

Convenient alias for .map() in cases where the function just needs to be called. as the caller doesn’t have to consume the generator to process the inputs.