Click performance is poor

[jonathan-s]

When I'm running click using a group I'm seeing pretty terrible performance. It's slow.

my_command  0.74s user 0.24s system 29% cpu 3.307 total

The only thing this executes is the help output, so most of the code it should be executing would be click code. The output is time my_command.

I don't know if I'm doing something wrong here myself, I'd be happy to take any suggestions for debugging the slowness here.

Environment:

• Python version: 3.8.16
• Click version: 8.1.7

[ThiefMaster]

Are you sure your command isn't simply importing lots of stuff from your application? Deferring imports until you actually need them will likely give you a massive performance increase if you're importing a big application behind.

[jonathan-s]

Thanks for putting me on the right track!

[ThiefMaster]

You may find this useful, I use it in my own application for exactly that reason:

class LazyGroup(click.Group):
    """
    A click Group that imports the actual implementation only when
    needed.  This allows for more resilient CLIs where the top-level
    command does not fail when a subcommand is broken enough to fail
    at import time.
    """

    def __init__(self, import_name, **kwargs):
        self._import_name = import_name
        super().__init__(**kwargs)

    @cached_property
    def _impl(self):
        module, name = self._import_name.split(':', 1)
        return getattr(import_module(module), name)

    def get_command(self, ctx, cmd_name):
        return self._impl.get_command(ctx, cmd_name)

    def list_commands(self, ctx):
        return self._impl.list_commands(ctx)

    def invoke(self, ctx):
        return self._impl.invoke(ctx)

    def get_usage(self, ctx):
        return self._impl.get_usage(ctx)

    def get_params(self, ctx):
        return self._impl.get_params(ctx)

An example of how I'm using it:

@cli.group(cls=LazyGroup, import_name='indico.cli.setup:cli')
def setup():
    """Setup Indico."""

The cli inside the referenced module is simply another click group.

[jonathan-s]

ah, that's pretty sweet! Thanks a lot!