import pytorch_lightning is too slow

[junsoo-ha-unknot]

Bug description

import pytorch_lightning takes about 2 seconds (~1 second when import torch has been executed before), which is relatively ~30x slower than import numpy, and ~15x slower than import pandas.

While ~2 second latency could be considered negligible for a computation-heavy applications, it becomes annoying, for example, when you try to build a CLI tool with autocompletion features. User wants quick response, but a simple tab completion would take at least ~2 seconds, just because of the slow import statement.

How to reproduce the bug

import time
start = time.time()
import numpy
np_end = time.time()
import pandas
pd_end = time.time()
import torch
torch_end = time.time()
import pytorch_lightning
pl_end = time.time()


print(f"np: {np_end - start}")
print(f"pd: {pd_end - np_end}")
print(f"torch: {torch_end - pd_end}")
print(f"pl: {pl_end - torch_end}")

Error messages and logs

np: 0.06890726089477539
pd: 0.12215876579284668
torch: 0.7145488262176514
pl: 0.9180386066436768

Environment

Current environment

* CUDA:
        - GPU:
                - NVIDIA A30
                - NVIDIA A30
                - NVIDIA A30
                - NVIDIA A30
                - NVIDIA A30
                - NVIDIA A30
                - NVIDIA A30
                - NVIDIA A30
        - available:         True
        - version:           11.7
* Lightning:
        - pytorch-lightning: 1.6.3
        - torch:             1.13.0
        - torchmetrics:      0.7.3
        - torchtyping:       0.1.4
        - torchvision:       0.14.0
* Packages:
        - absl-py:           0.15.0
        - aiohttp:           3.8.1
        - aiosignal:         1.2.0
        - ansible:           6.5.0
        - ansible-core:      2.13.5
        - anyio:             3.6.2
        - appdirs:           1.4.4
        - argon2-cffi:       21.3.0
        - argon2-cffi-bindings: 21.2.0
        - asttokens:         2.2.0
        - async-timeout:     4.0.2
        - attrs:             21.4.0
        - babel:             2.11.0
        - backcall:          0.2.0
        - backports.functools-lru-cache: 1.6.4
        - bcrypt:            4.0.1
        - beautifulsoup4:    4.11.1
        - bleach:            5.0.1
        - blinker:           1.4
        - boto3:             1.24.96
        - botocore:          1.27.96
        - bottleneck:        1.3.5
        - brotlipy:          0.7.0
        - cachecontrol:      0.12.11
        - cached-property:   1.5.2
        - cachetools:        4.2.2
        - cachy:             0.3.0
        - certifi:           2022.9.24
        - cffi:              1.15.1
        - cfgv:              3.3.1
        - charset-normalizer: 2.0.4
        - chart-studio:      1.1.0
        - click:             8.1.3
        - click-default-group: 1.2.2
        - clikit:            0.6.2
        - coloredlogs:       15.0.1
        - conda-lock:        1.2.1
        - contourpy:         1.0.5
        - crashtest:         0.3.1
        - cryptography:      37.0.1
        - cycler:            0.11.0
        - debugpy:           1.6.3
        - decorator:         5.1.1
        - deepdiff:          6.2.1
        - defusedxml:        0.7.1
        - distlib:           0.3.6
        - docker-pycreds:    0.4.0
        - docstring-to-markdown: 0.10
        - einops:            0.4.1
        - ensureconda:       1.4.3
        - entrypoints:       0.4
        - exceptiongroup:    1.0.2
        - exchange-calendars: 4.2.3
        - execnet:           1.9.0
        - executing:         1.2.0
        - fancycompleter:    0.9.1
        - fastjsonschema:    2.16.2
        - filelock:          3.8.0
        - fire:              0.4.0
        - flake8:            5.0.4
        - flatbuffers:       2.0
        - flit-core:         3.8.0
        - fonttools:         4.37.4
        - frozenlist:        1.2.0
        - fsspec:            2022.7.1
        - future:            0.18.2
        - gitdb:             4.0.9
        - gitpython:         3.1.29
        - gmpy2:             2.1.2
        - google-auth:       2.6.0
        - google-auth-oauthlib: 0.4.4
        - greenlet:          1.1.3.post0
        - grpcio:            1.42.0
        - h5py:              3.6.0
        - html5lib:          1.1
        - humanfriendly:     10.0
        - hurst:             0.0.5
        - identify:          2.5.6
        - idna:              3.4
        - importlib-metadata: 4.11.3
        - importlib-resources: 5.10.0
        - iniconfig:         1.1.1
        - ipdb:              0.13.9
        - ipykernel:         6.16.1
        - ipython:           8.7.0
        - ipython-genutils:  0.2.0
        - ipywidgets:        8.0.2
        - jaraco.classes:    3.2.3
        - jedi:              0.18.2
        - jedi-language-server: 0.37.0
        - jeepney:           0.8.0
        - jinja2:            3.1.2
        - jmespath:          1.0.1
        - json5:             0.9.5
        - jsonschema:        4.17.3
        - jupyter:           1.0.0
        - jupyter-client:    7.4.3
        - jupyter-console:   6.4.4
        - jupyter-core:      5.1.0
        - jupyter-server:    1.23.3
        - jupyterlab:        3.5.0
        - jupyterlab-pygments: 0.2.2
        - jupyterlab-server: 2.16.3
        - jupyterlab-vim:    0.15.1
        - jupyterlab-widgets: 3.0.3
        - keyring:           23.9.3
        - kiwisolver:        1.4.4
        - korean-lunar-calendar: 0.2.1
        - llvmlite:          0.38.0
        - lockfile:          0.12.2
        - markdown:          3.3.4
        - markupsafe:        2.1.1
        - matplotlib:        3.6.0
        - matplotlib-inline: 0.1.6
        - mccabe:            0.7.0
        - mistune:           2.0.4
        - mkl-fft:           1.3.1
        - mkl-random:        1.2.2
        - mkl-service:       2.4.0
        - more-itertools:    9.0.0
        - mpmath:            1.2.1
        - msgpack:           1.0.4
        - multidict:         6.0.2
        - namegenerator:     1.0.6
        - nbclassic:         0.4.8
        - nbclient:          0.7.2
        - nbconvert:         7.2.5
        - nbformat:          5.7.0
        - neovim:            0.3.1
        - nest-asyncio:      1.5.6
        - nodeenv:           1.7.0
        - notebook:          6.5.2
        - notebook-shim:     0.2.2
        - numba:             0.55.1
        - numexpr:           2.8.3
        - numpy:             1.21.5
        - nvidia-cublas-cu11: 11.10.3.66
        - nvidia-cuda-nvrtc-cu11: 11.7.99
        - nvidia-cuda-runtime-cu11: 11.7.99
        - nvidia-cudnn-cu11: 8.5.0.96
        - oauthlib:          3.2.1
        - onnxruntime:       1.12.1
        - ordered-set:       4.1.0
        - packaging:         21.3
        - pandas:            1.4.4
        - pandas-market-calendars: 4.1.0
        - pandocfilters:     1.5.0
        - paramiko:          2.12.0
        - parso:             0.8.3
        - pastel:            0.2.1
        - pathtools:         0.1.2
        - patsy:             0.5.3
        - pdbpp:             0.10.3
        - pexpect:           4.8.0
        - pickleshare:       0.7.5
        - pillow:            9.3.0
        - pip:               21.0.1
        - pkginfo:           1.8.3
        - pkgutil-resolve-name: 1.3.10
        - platformdirs:      2.5.2
        - plotly:            5.11.0
        - pluggy:            1.0.0
        - pre-commit:        2.20.0
        - prettytable:       3.5.0
        - prometheus-client: 0.15.0
        - promise:           2.3
        - prompt-toolkit:    3.0.33
        - protobuf:          3.20.1
        - psutil:            5.9.3
        - ptyprocess:        0.7.0
        - pudb:              2022.1.3
        - pure-eval:         0.2.2
        - py:                1.11.0
        - pyasn1:            0.4.8
        - pyasn1-modules:    0.2.8
        - pycodestyle:       2.9.1
        - pycparser:         2.21
        - pydantic:          1.9.2
        - pydeprecate:       0.3.2
        - pyflakes:          2.5.0
        - pygls:             0.12.2
        - pygments:          2.13.0
        - pyjwt:             2.4.0
        - pylev:             1.4.0
        - pyluach:           2.0.2
        - pynacl:            1.5.0
        - pynvim:            0.4.3
        - pyopenssl:         22.0.0
        - pyparsing:         3.0.9
        - pyrepl:            0.9.0
        - pyrsistent:        0.18.1
        - pysocks:           1.7.1
        - pytest:            7.2.0
        - pytest-forked:     1.4.0
        - pytest-xdist:      3.0.2
        - python-box:        6.1.0
        - python-dateutil:   2.8.2
        - pytorch-lightning: 1.6.3
        - pytz:              2022.1
        - pyyaml:            6.0
        - pyzmq:             24.0.1
        - qtconsole:         5.3.2
        - qtpy:              2.2.1
        - requests:          2.28.1
        - requests-oauthlib: 1.3.0
        - resolvelib:        0.8.1
        - retrying:          1.3.4
        - rsa:               4.7.2
        - ruamel.yaml:       0.17.21
        - ruamel.yaml.clib:  0.2.7
        - s3transfer:        0.6.0
        - scipy:             1.9.1
        - seaborn:           0.12.1
        - secretstorage:     3.3.3
        - send2trash:        1.8.0
        - sentry-sdk:        1.10.0
        - setproctitle:      1.3.2
        - setuptools:        58.0.4
        - shortuuid:         1.0.9
        - six:               1.16.0
        - slackclient:       2.9.4
        - smmap:             5.0.0
        - sniffio:           1.3.0
        - soupsieve:         2.3.2.post1
        - stack-data:        0.6.2
        - statsmodels:       0.13.5
        - sympy:             1.10.1
        - tenacity:          8.1.0
        - tensorboard:       2.9.0
        - tensorboard-data-server: 0.6.0
        - tensorboard-plugin-wit: 1.8.1
        - termcolor:         2.1.0
        - terminado:         0.17.0
        - tinycss2:          1.2.1
        - toml:              0.10.2
        - tomli:             2.0.1
        - tomlkit:           0.11.5
        - toolz:             0.12.0
        - torch:             1.13.0
        - torchmetrics:      0.7.3
        - torchtyping:       0.1.4
        - torchvision:       0.14.0
        - tornado:           6.2
        - tqdm:              4.64.1
        - traitlets:         5.6.0
        - typeguard:         2.13.3
        - typing-extensions: 4.3.0
        - urllib3:           1.26.12
        - urwid:             2.1.2
        - urwid-readline:    0.13
        - virtualenv:        20.16.5
        - wandb:             0.13.5
        - wcwidth:           0.2.5
        - webencodings:      0.5.1
        - websocket-client:  1.4.2

More info

No response

cc @Borda

[semaphore-egg]

Version 1.7.x is faster.

[awaelchli]

Hi @junsoo-ha-unknot
We already have some work started here: #12786
Lots of imports have already been refactored to load lazily.
Closing it because it's a duplicate. Thanks for reporting it!