modal.functions

modal.functions.Function

class Function(modal.object.Provider)

Functions are the basic units of serverless execution on Modal.

Generally, you will not construct a Function directly. Instead, use the @stub.function decorator on the Stub object for your application.

persist

@typechecked
def persist(self, label: str, namespace=api_pb2.DEPLOYMENT_NAMESPACE_WORKSPACE):

Deploy a Modal app containing this object. This object can then be imported from other apps using the returned reference, or by calling modal.SharedVolume.from_name(label) (or the equivalent method on respective class).

Example Usage

import modal

volume = modal.SharedVolume().persist("my-volume")

stub = modal.Stub()

# Volume refers to the same object, even across instances of `stub`.
@stub.function(shared_volumes={"/vol": volume})
def f():
    pass

from_name

@classmethod
def from_name(
    cls: Type[P], app_name: str, tag: Optional[str] = None, namespace=api_pb2.DEPLOYMENT_NAMESPACE_WORKSPACE
) -> P:

Returns a reference to an Modal object of any type

Useful for referring to already created/deployed objects, e.g., Secrets

import modal

stub = modal.Stub()

@stub.function(secret=modal.Secret.from_name("my-secret-name"))
def some_function():
    pass

lookup

@classmethod
def lookup(
    cls: Type[P],
    app_name: str,
    tag: Optional[str] = None,
    namespace=api_pb2.DEPLOYMENT_NAMESPACE_WORKSPACE,
    client: Optional[_Client] = None,
) -> H:

General purpose method to retrieve Modal objects such as functions, shared volumes, and secrets.

import modal
square = modal.Function.lookup("my-shared-app", "square")
assert square(3) == 9
vol = modal.SharedVolume.lookup("my-shared-volume")
for chunk in vol.read_file("my_db_dump.csv"):
    ...

get_panel_items

def get_panel_items(self) -> List[str]:

modal.functions.FunctionCall

class FunctionCall(modal.object.Handle)

A reference to an executed function call

Constructed using .spawn(...) on a Modal function with the same arguments that a function normally takes. Acts as a reference to an ongoing function call that can be passed around and used to poll or fetch function results at some later time.

Conceptually similar to a Future/Promise/AsyncResult in other contexts and languages.

def __init__(self):

from_id

@classmethod
def from_id(cls: Type[H], object_id: str, client: Optional[_Client] = None) -> H:

Get an object of this type from a unique object id (retrieved from obj.object_id)

object_id

@property
def object_id(self) -> str:

A unique object id for this instance. Can be used to retrieve the object using .from_id()

from_app

@classmethod
def from_app(
    cls: Type[H],
    app_name: str,
    tag: Optional[str] = None,
    namespace=api_pb2.DEPLOYMENT_NAMESPACE_WORKSPACE,
    client: Optional[_Client] = None,
) -> H:

Returns a handle to a tagged object in a deployment on Modal.

get

def get(self, timeout: Optional[float] = None):

Gets the result of the function call

Raises TimeoutError if no results are returned within timeout seconds. Setting timeout to None (the default) waits indefinitely until there is a result

get_call_graph

def get_call_graph(self) -> List[InputInfo]:

Returns a nested dictionary structure representing the call graph from a given root call ID, along with the status of execution for each node.

cancel

def cancel(self):

modal.functions.FunctionHandle

class FunctionHandle(modal.object.Handle)

Interact with a Modal Function of a live app.

def __init__(self):

from_id

@classmethod
def from_id(cls: Type[H], object_id: str, client: Optional[_Client] = None) -> H:

Get an object of this type from a unique object id (retrieved from obj.object_id)

object_id

@property
def object_id(self) -> str:

A unique object id for this instance. Can be used to retrieve the object using .from_id()

from_app

@classmethod
def from_app(
    cls: Type[H],
    app_name: str,
    tag: Optional[str] = None,
    namespace=api_pb2.DEPLOYMENT_NAMESPACE_WORKSPACE,
    client: Optional[_Client] = None,
) -> H:

Returns a handle to a tagged object in a deployment on Modal.

web_url

@property
def web_url(self) -> str:

URL of a Function running as a web endpoint.

is_generator

@property
def is_generator(self) -> bool:

map

@warn_if_generator_is_not_consumed
def map(
    self,
    *input_iterators,  # one input iterator per argument in the mapped-over function/generator
    kwargs={},  # any extra keyword arguments for the function
    order_outputs=None,  # defaults to True for regular functions, False for generators
    return_exceptions=False,  # whether to propogate exceptions (False) or aggregate them in the results list (True)
):

Parallel map over a set of inputs.

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

Example:

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

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.

If applied to a stub.generator, the results are returned as they are finished and can be out of order. By yielding zero or more than once, mapping over generators can also be used as a “flat map”.

return_exceptions can be used to treat exceptions as successful results:

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

# [0, 1, UserCodeException(Exception('ohno'))]
print(list(my_func.map(range(3), return_exceptions=True)))

for_each

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

Execute function for all outputs, 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.

starmap

@warn_if_generator_is_not_consumed
def starmap(self, input_iterator, kwargs={}, order_outputs=None, return_exceptions=False):

Like map but spreads arguments over multiple function arguments

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

Example:

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

assert list(my_func.starmap([(1, 2), (3, 4)])) == [3, 7]

call

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

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

spawn

def spawn(self, *args, **kwargs) -> Optional["_FunctionCall"]:

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

Returns a modal.functions.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.

Note: .spawn() on a modal generator function does call and execute the generator, but does not currently return a function handle for polling the result.

get_raw_f

def get_raw_f(self) -> Callable:

Return the inner Python object wrapped by this Modal Function.

get_current_stats

def get_current_stats(self) -> FunctionStats:

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

modal.functions.FunctionStats

class FunctionStats(object)

Simple data structure storing stats for a running function.

def __init__(self, backlog: int, num_active_runners: int, num_total_runners: int) -> None

modal.functions.current_input_id

def current_input_id() -> str:

Returns the input ID for the currently processed input.

Can only be called from Modal function (i.e. in a container context).

from modal import current_input_id

@stub.function
def process_stuff():
    print(f"Starting to process {current_input_id()}")

modal.functions.gather

def gather(*function_calls: _FunctionCall):

Wait until all Modal function calls have results before returning

Accepts a variable number of FunctionCall objects as returned by Function.spawn().

Returns a list of results from each function call, or raises an exception of the first failing function call.

E.g.

function_call_1 = slow_func_1.spawn()
function_call_2 = slow_func_2.spawn()

result_1, result_2 = gather(function_call_1, function_call_2)