From 39d9f94d132a69432f91eaaf893e38bc162623ad Mon Sep 17 00:00:00 2001
From: Sean Lip <sean@seanlip.org>
Date: Sat, 2 Nov 2024 03:13:38 +0800
Subject: [PATCH] Fix part of #21020: Upgrade Python to 3.9 (#21215)

* Update to python 3.9

* Fix isAlive

* Fix import ordering

* Fix import ordering

* Fix test

* use python3.9.20 for docker

* Fix lint errors, remove spurious changes

* Fix lint issues

* Address review comment.
---
 .../backend_associated_test_file_check.yml    |  4 +-
 .github/workflows/backend_tests.yml           | 12 +--
 .../workflows/check_test_suites_to_run.yml    |  4 +-
 ...ighthouse_performance_acceptance_tests.yml | 20 ++--
 .github/workflows/eslint_tests.yml            |  4 +-
 .github/workflows/frontend_tests.yml          |  4 +-
 .../workflows/lighthouse_accessibility.yml    |  8 +-
 .github/workflows/lint.yml                    |  4 +-
 .../workflows/pending-review-notification.yml |  4 +-
 .github/workflows/prettier.yml                |  4 +-
 .github/workflows/python_type_checks.yml      |  4 +-
 ...typescript_and_e2e_acceptance_coverage.yml |  4 +-
 app_dev.yaml                                  |  2 +-
 core/tests/test_utils.py                      | 99 +++----------------
 docker/Dockerfile.backend                     |  2 +-
 docker/dev-server.entrypoint.sh               |  2 +-
 mypy.ini                                      |  2 +-
 requirements.txt                              |  2 +-
 requirements_dev.txt                          |  2 +-
 scripts/concurrent_task_utils.py              |  2 +-
 scripts/install_python_prod_dependencies.py   |  4 +-
 .../install_python_prod_dependencies_test.py  |  4 +-
 scripts/linters/run_lint_checks.py            |  8 +-
 scripts/pre_commit_hook.py                    | 19 ++--
 scripts/pre_push_hook.py                      | 13 ++-
 .../repo_specific_changes_fetcher.py          |  8 +-
 scripts/run_e2e_tests.py                      | 15 +--
 scripts/run_frontend_tests.py                 | 16 ++-
 scripts/run_lighthouse_tests.py               | 15 +--
 scripts/run_portserver.py                     |  8 +-
 scripts/run_typescript_checks.py              | 14 +--
 scripts/setup.py                              |  4 +-
 scripts/setup_test.py                         |  8 +-
 scripts/third_party_size_check.py             | 10 +-
 stubs/threading/__init__.pyi                  |  8 +-
 35 files changed, 123 insertions(+), 220 deletions(-)

diff --git a/.github/workflows/backend_associated_test_file_check.yml b/.github/workflows/backend_associated_test_file_check.yml
index 08af0ae96535..bacec7c69677 100644
--- a/.github/workflows/backend_associated_test_file_check.yml
+++ b/.github/workflows/backend_associated_test_file_check.yml
@@ -21,10 +21,10 @@ jobs:
     steps:
       - name: Checkout repository
         uses: actions/checkout@v3
-      - name: Setup Python 3.8
+      - name: Setup Python 3.9.20
         uses: actions/setup-python@v4
         with:
-          python-version: '3.8.15'
+          python-version: '3.9.20'
           architecture: 'x64'
       - name: Merge develop branch into the current branch
         uses: ./.github/actions/merge
diff --git a/.github/workflows/backend_tests.yml b/.github/workflows/backend_tests.yml
index 22e3a126ecbc..535a3f0e3998 100644
--- a/.github/workflows/backend_tests.yml
+++ b/.github/workflows/backend_tests.yml
@@ -22,10 +22,10 @@ jobs:
     steps:
       - name: Checkout repository
         uses: actions/checkout@v3
-      - name: Setup Python 3.8
+      - name: Setup Python 3.9.20
         uses: actions/setup-python@v4
         with:
-          python-version: '3.8.15'
+          python-version: '3.9.20'
           architecture: 'x64'
       - name: Initialize Containers
         if: startsWith(github.head_ref, 'update-changelog-for-release') == false
@@ -60,10 +60,10 @@ jobs:
     steps:
       - name: Checkout repository
         uses: actions/checkout@v3
-      - name: Setup Python 3.8
+      - name: Setup Python 3.9.20
         uses: actions/setup-python@v4
         with:
-          python-version: '3.8.15'
+          python-version: '3.9.20'
           architecture: 'x64'
       - name: Install coverage
         if: startsWith(github.head_ref, 'update-changelog-for-release') == false
@@ -130,10 +130,10 @@ jobs:
     steps:
       - name: Checkout repository
         uses: actions/checkout@v3
-      - name: Setup Python 3.8
+      - name: Setup Python 3.9.20
         uses: actions/setup-python@v4
         with:
-          python-version: '3.8.15'
+          python-version: '3.9.20'
           architecture: 'x64'
       - name: Download time report for shard 1
         uses: actions/download-artifact@v3
diff --git a/.github/workflows/check_test_suites_to_run.yml b/.github/workflows/check_test_suites_to_run.yml
index 7c466631249d..33d10fdbf5ac 100644
--- a/.github/workflows/check_test_suites_to_run.yml
+++ b/.github/workflows/check_test_suites_to_run.yml
@@ -22,10 +22,10 @@ jobs:
           fetch-depth: 0
       - name: Merge develop branch into the current branch
         uses: ./.github/actions/merge
-      - name: Setup Python 3.8 with pip cache
+      - name: Setup Python 3.9.20 with pip cache
         uses: actions/setup-python@v4
         with:
-          python-version: '3.8.15'
+          python-version: '3.9.20'
           architecture: 'x64'
           cache: 'pip'
           cache-dependency-path: |
diff --git a/.github/workflows/e2e_lighthouse_performance_acceptance_tests.yml b/.github/workflows/e2e_lighthouse_performance_acceptance_tests.yml
index e4f716c13066..bdf1693a66d2 100644
--- a/.github/workflows/e2e_lighthouse_performance_acceptance_tests.yml
+++ b/.github/workflows/e2e_lighthouse_performance_acceptance_tests.yml
@@ -26,10 +26,10 @@ jobs:
     steps:
       - name: Checkout repository
         uses: actions/checkout@v3
-      - name: Setup Python 3.8 with pip cache
+      - name: Setup Python 3.9.20 with pip cache
         uses: actions/setup-python@v4
         with:
-          python-version: '3.8.15'
+          python-version: '3.9.20'
           architecture: 'x64'
           cache: 'pip'
           cache-dependency-path: |
@@ -84,10 +84,10 @@ jobs:
     steps:
       - name: Checkout repository
         uses: actions/checkout@v3
-      - name: Setup Python 3.8 with pip cache
+      - name: Setup Python 3.9.20 with pip cache
         uses: actions/setup-python@v4
         with:
-          python-version: '3.8.15'
+          python-version: '3.9.20'
           architecture: 'x64'
           cache: 'pip'
           cache-dependency-path: |
@@ -200,10 +200,10 @@ jobs:
     steps:
       - name: Checkout repository
         uses: actions/checkout@v3
-      - name: Setup Python 3.8
+      - name: Setup Python 3.9.20
         uses: actions/setup-python@v4
         with:
-          python-version: '3.8.15'
+          python-version: '3.9.20'
           architecture: 'x64'
       - name: Merge develop branch into the current branch
         uses: ./.github/actions/merge
@@ -290,10 +290,10 @@ jobs:
       steps:
         - name: Checkout repository
           uses: actions/checkout@v3
-        - name: Setup Python 3.8 with pip cache
+        - name: Setup Python 3.9.20 with pip cache
           uses: actions/setup-python@v4
           with:
-            python-version: '3.8.15'
+            python-version: '3.9.20'
             architecture: 'x64'
             cache: 'pip'
             cache-dependency-path: |
@@ -393,10 +393,10 @@ jobs:
     steps:
       - name: Checkout repository
         uses: actions/checkout@v3
-      - name: Setup Python 3.8
+      - name: Setup Python 3.9.20
         uses: actions/setup-python@v4
         with:
-          python-version: '3.8.15'
+          python-version: '3.9.20'
           architecture: 'x64'
       - name: Merge develop branch into the current branch
         uses: ./.github/actions/merge
diff --git a/.github/workflows/eslint_tests.yml b/.github/workflows/eslint_tests.yml
index 1e29e958211c..3494d4f2c7ea 100644
--- a/.github/workflows/eslint_tests.yml
+++ b/.github/workflows/eslint_tests.yml
@@ -21,10 +21,10 @@ jobs:
     steps:
       - name: Checkout repository
         uses: actions/checkout@v3
-      - name: Setup Python 3.8
+      - name: Setup Python 3.9.20
         uses: actions/setup-python@v4
         with:
-          python-version: '3.8.15'
+          python-version: '3.9.20'
           architecture: 'x64'
       - name: Merge develop branch into the current branch
         uses: ./.github/actions/merge
diff --git a/.github/workflows/frontend_tests.yml b/.github/workflows/frontend_tests.yml
index f8f153a655b5..0448dbc3db00 100644
--- a/.github/workflows/frontend_tests.yml
+++ b/.github/workflows/frontend_tests.yml
@@ -50,10 +50,10 @@ jobs:
           ls /home/runner/work/oppia
           ls /home/runner/work/oppia/oppia
           echo $GITHUB_WORKSPACE
-      - name: Setup Python 3.8
+      - name: Setup Python 3.9.20
         uses: actions/setup-python@v4
         with:
-          python-version: '3.8.15'
+          python-version: '3.9.20'
           architecture: 'x64'
       - name: Merge develop branch into the current branch
         uses: ./.github/actions/merge
diff --git a/.github/workflows/lighthouse_accessibility.yml b/.github/workflows/lighthouse_accessibility.yml
index ffa7912d6865..716d83ba9cff 100644
--- a/.github/workflows/lighthouse_accessibility.yml
+++ b/.github/workflows/lighthouse_accessibility.yml
@@ -26,10 +26,10 @@ jobs:
     steps:
       - name: Checkout repository
         uses: actions/checkout@v3
-      - name: Setup Python 3.8
+      - name: Setup Python 3.9.20
         uses: actions/setup-python@v4
         with:
-          python-version: '3.8.15'
+          python-version: '3.9.20'
           architecture: 'x64'
       - name: Merge develop branch into the current branch
         uses: ./.github/actions/merge
@@ -91,10 +91,10 @@ jobs:
     steps:
       - name: Checkout repository
         uses: actions/checkout@v3
-      - name: Setup Python 3.8
+      - name: Setup Python 3.9.20
         uses: actions/setup-python@v4
         with:
-          python-version: '3.8.15'
+          python-version: '3.9.20'
           architecture: 'x64'
       - name: Merge develop branch into the current branch
         uses: ./.github/actions/merge
diff --git a/.github/workflows/lint.yml b/.github/workflows/lint.yml
index 9acd447ef900..4af3b5e81fc9 100644
--- a/.github/workflows/lint.yml
+++ b/.github/workflows/lint.yml
@@ -21,10 +21,10 @@ jobs:
     steps:
       - name: Checkout repository
         uses: actions/checkout@v3
-      - name: Setup Python 3.8 with pip cache
+      - name: Setup Python 3.9.20 with pip cache
         uses: actions/setup-python@v4
         with:
-          python-version: '3.8.15'
+          python-version: '3.9.20'
           architecture: 'x64'
       - name: Free disk space
         run: |
diff --git a/.github/workflows/pending-review-notification.yml b/.github/workflows/pending-review-notification.yml
index 6324dd6ce775..c66f2d55943b 100644
--- a/.github/workflows/pending-review-notification.yml
+++ b/.github/workflows/pending-review-notification.yml
@@ -19,10 +19,10 @@ jobs:
     steps:
       - name: Checkout repository
         uses: actions/checkout@v3
-      - name: Setup Python 3.8
+      - name: Setup Python 3.9.20
         uses: actions/setup-python@v4
         with:
-          python-version: '3.8.15'
+          python-version: '3.9.20'
           architecture: 'x64'
         # SHA1 hash of the develop commit.
       - name: Notify reviewers
diff --git a/.github/workflows/prettier.yml b/.github/workflows/prettier.yml
index 5f9749fd7600..f041203d83bc 100644
--- a/.github/workflows/prettier.yml
+++ b/.github/workflows/prettier.yml
@@ -21,10 +21,10 @@ jobs:
     steps:
       - name: Checkout repository
         uses: actions/checkout@v3
-      - name: Setup Python 3.8
+      - name: Setup Python 3.9.20
         uses: actions/setup-python@v4
         with:
-          python-version: '3.8.15'
+          python-version: '3.9.20'
           architecture: 'x64'
       - name: Merge develop branch into the current branch
         uses: ./.github/actions/merge
diff --git a/.github/workflows/python_type_checks.yml b/.github/workflows/python_type_checks.yml
index afa09bbd3110..d8518286f581 100644
--- a/.github/workflows/python_type_checks.yml
+++ b/.github/workflows/python_type_checks.yml
@@ -21,10 +21,10 @@ jobs:
     steps:
       - name: Checkout repository
         uses: actions/checkout@v3
-      - name: Setup Python 3.8
+      - name: Setup Python 3.9.20
         uses: actions/setup-python@v4
         with:
-          python-version: '3.8.15'
+          python-version: '3.9.20'
           architecture: 'x64'
       - name: Merge develop branch into the current branch
         uses: ./.github/actions/merge
diff --git a/.github/workflows/typescript_and_e2e_acceptance_coverage.yml b/.github/workflows/typescript_and_e2e_acceptance_coverage.yml
index 81edd6e54a51..4bd63e401947 100644
--- a/.github/workflows/typescript_and_e2e_acceptance_coverage.yml
+++ b/.github/workflows/typescript_and_e2e_acceptance_coverage.yml
@@ -20,10 +20,10 @@ jobs:
     steps:
       - name: Checkout repository
         uses: actions/checkout@v3
-      - name: Setup Python 3.8
+      - name: Setup Python 3.9.20
         uses: actions/setup-python@v4
         with:
-          python-version: '3.8.15'
+          python-version: '3.9.20'
           architecture: 'x64'
       - name: Free disk space
         run: |
diff --git a/app_dev.yaml b/app_dev.yaml
index ad8f2fbb48d4..9d329d610393 100644
--- a/app_dev.yaml
+++ b/app_dev.yaml
@@ -1,4 +1,4 @@
-runtime: python38
+runtime: python39
 instance_class: F2
 # The "version" line is added here so that MR jobs can run locally (see issue
 # #6534 on oppia/oppia).
diff --git a/core/tests/test_utils.py b/core/tests/test_utils.py
index bd7ef38a1fec..4091d1fce02c 100644
--- a/core/tests/test_utils.py
+++ b/core/tests/test_utils.py
@@ -25,6 +25,7 @@
 import datetime
 import functools
 import inspect
+import io
 import itertools
 import json
 import logging
@@ -33,7 +34,6 @@
 import random
 import re
 import string
-from types import TracebackType
 import unittest
 
 from core import feature_flag_list
@@ -87,9 +87,9 @@
 import elasticsearch
 import requests_mock
 from typing import (
-    IO, Any, Callable, Collection, Dict, Final, Iterable, Iterator, List,
-    Literal, Mapping, Optional, OrderedDict, Pattern, Sequence, Set, Tuple,
-    Type, TypedDict, TypeVar, Union, cast, overload
+    Any, Callable, Collection, Dict, Final, Iterable, Iterator, List,
+    Literal, Mapping, Optional, OrderedDict, Pattern, Sequence, Set,
+    Tuple, Type, TypedDict, TypeVar, Union, cast, overload
 )
 import webapp2
 import webtest
@@ -1505,94 +1505,25 @@ def capture_logging(
         """
         captured_logs: List[str] = []
 
-        class ListStream(IO[str]):
+        class ListStream(io.StringIO):
             """Stream-like object that appends writes to the captured logs."""
 
-            # Here we use MyPy ignore because the signature of this
-            # method doesn't match with IO's write().
-            def write(self, msg: str) -> None:  # type: ignore[override]
-                """Appends stripped messages to captured logs."""
+            def write(self, msg: str) -> int:
+                """Appends stripped messages to captured logs.
+
+                Args:
+                    msg: str. The string to be written.
+
+                Returns:
+                    int. The length of the written string in bytes.
+                """
                 captured_logs.append(msg.strip())
+                return len(msg.strip())
 
             def flush(self) -> None:
                 """Does nothing."""
                 pass
 
-            # Here, class ListStream inherits from IO and making an instance
-            # below but due to the absence of some methods MyPy throws an error
-            # that 'Cannot instantiate abstract class 'ListStream' with abstract
-            # attributes'. So, to suppress the error, we defined all the methods
-            # that was present in super class. Since these are just added for
-            # type checking, we don't need to test them and so have excluded
-            # them from the coverage checks.
-            @property
-            def mode(self) -> str:
-                pass  # pragma: no cover
-
-            @property
-            def name(self) -> str:
-                pass  # pragma: no cover
-
-            def close(self) -> None:
-                pass  # pragma: no cover
-
-            @property
-            def closed(self) -> bool:
-                pass  # pragma: no cover
-
-            def fileno(self) -> int:
-                pass  # pragma: no cover
-
-            def isatty(self) -> bool:
-                pass  # pragma: no cover
-
-            def read(self, n: int = -1) -> str:
-                pass  # pragma: no cover
-
-            def readable(self) -> bool:
-                pass  # pragma: no cover
-
-            def readline(self, limit: int = -1) -> str:
-                pass  # pragma: no cover
-
-            def readlines(self, hint: int = -1) -> List[str]:
-                pass  # pragma: no cover
-
-            def seek(self, offset: int, whence: int = 0) -> int:
-                pass  # pragma: no cover
-
-            def seekable(self) -> bool:
-                pass  # pragma: no cover
-
-            def tell(self) -> int:
-                pass  # pragma: no cover
-
-            def truncate(self, size: Optional[int] = None) -> int:
-                pass  # pragma: no cover
-
-            def writable(self) -> bool:
-                pass  # pragma: no cover
-
-            def writelines(self, lines: Iterable[str]) -> None:
-                pass  # pragma: no cover
-
-            def __enter__(self) -> IO[str]:
-                pass  # pragma: no cover
-
-            def __exit__(
-                self,
-                type: Optional[Type[BaseException]], # pylint: disable=redefined-builtin
-                value: Optional[BaseException],
-                traceback: Optional[TracebackType]
-            ) -> None:
-                pass  # pragma: no cover
-
-            def __iter__(self) -> Iterator[str]:
-                pass  # pragma: no cover
-
-            def __next__(self) -> str:
-                pass  # pragma: no cover
-
         list_stream_handler = logging.StreamHandler(ListStream())
 
         logger = logging.getLogger()
diff --git a/docker/Dockerfile.backend b/docker/Dockerfile.backend
index 4112fcd83aa6..1c3c1e39de8f 100644
--- a/docker/Dockerfile.backend
+++ b/docker/Dockerfile.backend
@@ -1,5 +1,5 @@
 # Added platform flag here because -- https://stackoverflow.com/questions/71040681/qemu-x86-64-could-not-open-lib64-ld-linux-x86-64-so-2-no-such-file-or-direc
-FROM --platform=linux/amd64 python:3.8.17-slim-buster AS backend
+FROM --platform=linux/amd64 python:3.9.20-bullseye AS backend
 
 ENV OPPIA_IS_DOCKERIZED="true"
 
diff --git a/docker/dev-server.entrypoint.sh b/docker/dev-server.entrypoint.sh
index ffe054af5208..d7843d3bad49 100644
--- a/docker/dev-server.entrypoint.sh
+++ b/docker/dev-server.entrypoint.sh
@@ -15,7 +15,7 @@
 
 build_cmd="python -m scripts.build"
 dev_appserver_cmd="/app/vm_deps/google-cloud-sdk/bin/dev_appserver.py \
---runtime=python38 \
+--runtime=python39 \
 --host=0.0.0.0 \
 --port=8181 \
 --admin_host=0.0.0.0 \
diff --git a/mypy.ini b/mypy.ini
index 676ad5c03293..955a986302af 100644
--- a/mypy.ini
+++ b/mypy.ini
@@ -1,5 +1,5 @@
 [mypy]
-python_version = 3.8
+python_version = 3.9
 
 # Ignore if stubs of a third-party library is missing.
 ignore_missing_imports = True
diff --git a/requirements.txt b/requirements.txt
index 637775c8b877..2100082e8974 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -3,7 +3,7 @@
 # please change the `requirements.in` file, and then follow
 # the instructions there to regenerate this file.
 #
-# This file is autogenerated by pip-compile with Python 3.8
+# This file is autogenerated by pip-compile with Python 3.9
 # by the following command:
 #
 #    pip-compile --generate-hashes --no-emit-index-url --output-file=requirements.txt requirements.in
diff --git a/requirements_dev.txt b/requirements_dev.txt
index bb69ecd380a1..b749ba284a00 100644
--- a/requirements_dev.txt
+++ b/requirements_dev.txt
@@ -1,5 +1,5 @@
 #
-# This file is autogenerated by pip-compile with Python 3.8
+# This file is autogenerated by pip-compile with Python 3.9
 # by the following command:
 #
 #    pip-compile --generate-hashes --no-emit-index-url --output-file=requirements_dev.txt requirements_dev.in
diff --git a/scripts/concurrent_task_utils.py b/scripts/concurrent_task_utils.py
index 37eb8aabf55f..31a6f1aa73d6 100644
--- a/scripts/concurrent_task_utils.py
+++ b/scripts/concurrent_task_utils.py
@@ -152,7 +152,7 @@ def _check_all_tasks(tasks: List[TaskThread]) -> None:
     running_tasks_data = []
 
     for task in tasks:
-        if task.isAlive():
+        if task.is_alive():
             running_tasks_data.append('  %s (started %s)' % (
                 task.name,
                 time.strftime('%H:%M:%S', time.localtime(task.start_time))
diff --git a/scripts/install_python_prod_dependencies.py b/scripts/install_python_prod_dependencies.py
index 1e3ff48f6942..d3e98c924a6d 100644
--- a/scripts/install_python_prod_dependencies.py
+++ b/scripts/install_python_prod_dependencies.py
@@ -432,9 +432,9 @@ def _get_possible_normalized_metadata_directory_names(
             '%s-%s.egg-info' % (
                 library_name.replace('-', '_'), version_string)),
         normalize_directory_name(
-            '%s-%s-py3.8.egg-info' % (library_name, version_string)),
+            '%s-%s-py3.9.egg-info' % (library_name, version_string)),
         normalize_directory_name(
-            '%s-%s-py3.8.egg-info' % (
+            '%s-%s-py3.9.egg-info' % (
                 library_name.replace('-', '_'), version_string))
     }
 
diff --git a/scripts/install_python_prod_dependencies_test.py b/scripts/install_python_prod_dependencies_test.py
index 7db00693418e..21a2ba1f766f 100644
--- a/scripts/install_python_prod_dependencies_test.py
+++ b/scripts/install_python_prod_dependencies_test.py
@@ -629,8 +629,8 @@ def mock_list_dir(unused_path: str) -> List[str]:
             return [
                 'dependency-1-1.5.1.dist-info',
                 'dependency2-5.0.0.egg-info',
-                'dependency-5-0.5.3-py3.8.egg-info',
-                'dependency_6-0.5.3-py3.8.egg-info',
+                'dependency-5-0.5.3-py3.9.egg-info',
+                'dependency_6-0.5.3-py3.9.egg-info',
             ]
 
         def mock_is_dir(unused_path: str) -> bool:
diff --git a/scripts/linters/run_lint_checks.py b/scripts/linters/run_lint_checks.py
index 2a47e0a69fb0..f99aecb8bf45 100644
--- a/scripts/linters/run_lint_checks.py
+++ b/scripts/linters/run_lint_checks.py
@@ -63,13 +63,9 @@
 import sys
 import threading
 
+from core import utils
+from scripts import common
 from typing import Dict, List, Optional, Set, Tuple
-# TODO(#15567): This can be removed after Literal in utils.py is loaded
-# from typing instead of typing_extensions, this will be possible after
-# we migrate to Python 3.8.
-from scripts import common  # isort:skip pylint: disable=wrong-import-position
-
-from core import utils  # isort:skip
 
 # Install third party dependencies before proceeding.
 from . import codeowner_linter  # isort:skip
diff --git a/scripts/pre_commit_hook.py b/scripts/pre_commit_hook.py
index 12a893138195..fee4909600ff 100755
--- a/scripts/pre_commit_hook.py
+++ b/scripts/pre_commit_hook.py
@@ -34,13 +34,20 @@
 import subprocess
 import sys
 
-from typing import Final, List, Optional, Tuple
-
-# TODO(#15567): The order can be fixed after Literal in utils.py is loaded
-# from typing instead of typing_extensions, this will be possible after
-# we migrate to Python 3.8.
+# When executing Python scripts using `python -m ...` from oppia/oppia,
+# Python adds the repository root to sys.path. See the documentation at
+#
+#   https://docs.python.org/3.9/library/sys.html#sys.path
+#
+# However, when git executes pre_commit_hook.py from its symlink in
+# /.git/hooks, the shebang #!/usr/bin/env python at the top of this file
+# causes the python interpreter to execute this hook directly rather than
+# as a discovered module. So, Python instead adds /.git/hooks to sys.path,
+# rather than the opipa/oppia root. To correct this problem, we add the
+# current working directory to sys.path.
 sys.path.append(os.getcwd())
-from scripts import common  # isort:skip # pylint: disable=wrong-import-position
+from scripts import common  # isort:skip  # pylint: disable=wrong-import-position
+from typing import Final, List, Optional, Tuple  # isort:skip  # pylint: disable=wrong-import-position
 
 FECONF_FILEPATH: Final = os.path.join('core', 'feconf.py')
 CONSTANTS_FILEPATH: Final = os.path.join('.', 'assets', 'constants.ts')
diff --git a/scripts/pre_push_hook.py b/scripts/pre_push_hook.py
index 3eaf0c984776..a70319beab7e 100755
--- a/scripts/pre_push_hook.py
+++ b/scripts/pre_push_hook.py
@@ -39,8 +39,17 @@
 from types import TracebackType
 from typing import Final, List, Optional, Type
 
-# `pre_push_hook.py` is symlinked into `/.git/hooks`, so we explicitly import
-# the current working directory so that Git knows where to find python_utils.
+# When executing Python scripts using `python -m ...` from oppia/oppia,
+# Python adds the repository root to sys.path. See the documentation at
+#
+#   https://docs.python.org/3.9/library/sys.html#sys.path
+#
+# However, when git executes pre_push_hook.py from its symlink in
+# /.git/hooks, the shebang #!/usr/bin/env python at the top of this file
+# causes the python interpreter to execute this hook directly rather than
+# as a discovered module. So, Python instead adds /.git/hooks to sys.path,
+# rather than the opipa/oppia root. To correct this problem, we add the
+# current working directory to sys.path.
 sys.path.append(os.getcwd())
 from scripts import common  # isort:skip  # pylint: disable=wrong-import-position
 from scripts import install_python_prod_dependencies # isort:skip  # pylint: disable=wrong-import-position
diff --git a/scripts/release_scripts/repo_specific_changes_fetcher.py b/scripts/release_scripts/repo_specific_changes_fetcher.py
index 833b89f10384..3d11526d8365 100644
--- a/scripts/release_scripts/repo_specific_changes_fetcher.py
+++ b/scripts/release_scripts/repo_specific_changes_fetcher.py
@@ -24,14 +24,10 @@
 import os
 import re
 
+from core import utils
+from scripts import common
 from typing import Dict, Final, List, Optional
 
-# TODO(#15567): The order can be fixed after Literal in utils.py is loaded
-# from typing instead of typing_extensions, this will be possible after
-# we migrate to Python 3.8.
-from scripts import common  # isort:skip  # pylint: disable=wrong-import-position
-from core import utils  # isort:skip  # pylint: disable=wrong-import-position
-
 GIT_CMD_DIFF_NAMES_ONLY_FORMAT_STRING: Final = 'git diff --name-only %s %s'
 GIT_CMD_SHOW_FORMAT_STRING: Final = 'git show %s:core/feconf.py'
 VERSION_RE_FORMAT_STRING: Final = r'%s\s*=\s*(\d+|\.)+'
diff --git a/scripts/run_e2e_tests.py b/scripts/run_e2e_tests.py
index 375e9ccf4ee1..6a86a58d05da 100644
--- a/scripts/run_e2e_tests.py
+++ b/scripts/run_e2e_tests.py
@@ -22,18 +22,13 @@
 import subprocess
 import sys
 
+from core.constants import constants
+from scripts import build
+from scripts import common
+from scripts import install_third_party_libs
+from scripts import servers
 from typing import Final, List, Optional, Tuple
 
-# TODO(#15567): This can be removed after Literal in utils.py is loaded
-# from typing instead of typing_extensions, this will be possible after
-# we migrate to Python 3.8.
-from scripts import common  # isort:skip pylint: disable=wrong-import-position, unused-import
-
-from core.constants import constants  # isort:skip
-from scripts import build  # isort:skip
-from scripts import install_third_party_libs  # isort:skip
-from scripts import servers  # isort:skip
-
 MAX_RETRY_COUNT: Final = 3
 
 _PARSER: Final = argparse.ArgumentParser(
diff --git a/scripts/run_frontend_tests.py b/scripts/run_frontend_tests.py
index ab91b5b2f442..32bc36671b8a 100644
--- a/scripts/run_frontend_tests.py
+++ b/scripts/run_frontend_tests.py
@@ -21,17 +21,13 @@
 import subprocess
 import sys
 
-# TODO(#15567): This can be removed after Literal in utils.py is loaded
-# from typing instead of typing_extensions, this will be possible after
-# we migrate to Python 3.8.
-from scripts import common  # isort:skip pylint: disable=wrong-import-position, unused-import
-from scripts import git_changes_utils # isort:skip pylint: disable=wrong-import-position, unused-import
+from scripts import common
+from scripts import git_changes_utils
+from typing import Optional, Sequence, Set
 
-from typing import Optional, Sequence, Set  # isort:skip
-
-from . import build  # isort:skip
-from . import check_frontend_test_coverage  # isort:skip
-from . import install_third_party_libs  # isort:skip
+from . import build
+from . import check_frontend_test_coverage
+from . import install_third_party_libs
 
 # These is a relative path from the oppia/ folder. They are relative because the
 # dtslint command prepends the current working directory to the path, even if
diff --git a/scripts/run_lighthouse_tests.py b/scripts/run_lighthouse_tests.py
index 61a1831abc96..13d4457804b5 100644
--- a/scripts/run_lighthouse_tests.py
+++ b/scripts/run_lighthouse_tests.py
@@ -25,18 +25,13 @@
 import subprocess
 import sys
 
+from core import feconf
+from core.constants import constants
+from scripts import build
+from scripts import common
+from scripts import servers
 from typing import Final, List, Optional
 
-# TODO(#15567): This can be removed after Literal in utils.py is loaded
-# from typing instead of typing_extensions, this will be possible after
-# we migrate to Python 3.8.
-from scripts import common  # isort:skip pylint: disable=wrong-import-position
-
-from core import feconf # isort:skip
-from core.constants import constants  # isort:skip
-from scripts import build  # isort:skip
-from scripts import servers  # isort:skip
-
 LIGHTHOUSE_MODE_PERFORMANCE: Final = 'performance'
 LIGHTHOUSE_MODE_ACCESSIBILITY: Final = 'accessibility'
 SERVER_MODE_PROD: Final = 'dev'
diff --git a/scripts/run_portserver.py b/scripts/run_portserver.py
index dbf41972be92..1908d537b500 100644
--- a/scripts/run_portserver.py
+++ b/scripts/run_portserver.py
@@ -57,15 +57,9 @@
 import sys
 import threading
 
+from core import utils
 from typing import Callable, Deque, Final, List, Optional, Sequence
 
-# TODO(#15567): This can be removed after Literal in utils.py is loaded
-# from typing instead of typing_extensions, this will be possible after
-# we migrate to Python 3.8.
-from scripts import common  # isort:skip pylint: disable=wrong-import-position, unused-import
-
-from core import utils   # isort:skip
-
 _PROTOCOLS: Final = [
     (socket.SOCK_STREAM, socket.IPPROTO_TCP),
     (socket.SOCK_DGRAM, socket.IPPROTO_UDP)
diff --git a/scripts/run_typescript_checks.py b/scripts/run_typescript_checks.py
index 3faed844dc3a..ed1fa708669b 100644
--- a/scripts/run_typescript_checks.py
+++ b/scripts/run_typescript_checks.py
@@ -23,18 +23,12 @@
 import subprocess
 import sys
 
+from core import utils
+from scripts import common
 from typing import List, Optional, Sequence
+import yaml
 
-# TODO(#15567): This can be removed after Literal in utils.py is loaded
-# from typing instead of typing_extensions, this will be possible after
-# we migrate to Python 3.8.
-from scripts import common  # isort:skip pylint: disable=wrong-import-position, unused-import
-from . import build # isort:skip  pylint: disable=wrong-import-position, wrong-import-order
-
-from core import utils # isort:skip
-
-import yaml # isort:skip
-
+from . import build
 
 # Contains the name of all files that are not strictly typed.
 # This list must be kept up-to-date; the changes (only remove) should be done
diff --git a/scripts/setup.py b/scripts/setup.py
index ae71f3bf7226..ed38f00f842c 100644
--- a/scripts/setup.py
+++ b/scripts/setup.py
@@ -50,8 +50,8 @@ def create_directory(directory_path: str) -> None:
 # if it does not match the expected prefix.
 def test_python_version() -> None:
     running_python_version = '{0[0]}.{0[1]}.{0[2]}'.format(sys.version_info)
-    if running_python_version != '3.8.15':
-        print('Please use Python 3.8.15. Exiting...')
+    if running_python_version != '3.9.20':
+        print('Please use Python 3.9.20. Exiting...')
         # If OS is Windows, print helpful error message about adding Python to
         # path.
         if common.is_windows_os():
diff --git a/scripts/setup_test.py b/scripts/setup_test.py
index 806164737e66..0094540fac55 100644
--- a/scripts/setup_test.py
+++ b/scripts/setup_test.py
@@ -122,8 +122,8 @@ def mock_get(unused_var: str) -> None:
         self.cd_swap = self.swap(common, 'CD', MockCD)
         version_info = collections.namedtuple(
             'version_info', ['major', 'minor', 'micro'])
-        self.version_info_py38_swap = self.swap(
-            sys, 'version_info', version_info(major=3, minor=8, micro=15)
+        self.version_info_py39_swap = self.swap(
+            sys, 'version_info', version_info(major=3, minor=9, micro=20)
         )
         self.python2_print_swap = self.swap_with_checks(
             builtins,
@@ -161,7 +161,7 @@ def mock_makedirs(unused_path: str) -> None:
         self.assertFalse(check_function_calls['makedirs_is_called'])
 
     def test_python_version_testing_with_correct_version(self) -> None:
-        with self.version_info_py38_swap:
+        with self.version_info_py39_swap:
             setup.test_python_version()
 
     def test_python_version_testing_with_incorrect_version_and_linux_os(
@@ -224,7 +224,7 @@ def mock_print(msg_list: List[str]) -> None:
     def test_python_version_testing_with_python2_wrong_code(self) -> None:
         check_call_swap = self.swap_to_always_return(subprocess, 'call', 1)
 
-        with self.python2_print_swap, self.version_info_py38_swap:
+        with self.python2_print_swap, self.version_info_py39_swap:
             with check_call_swap, self.assertRaisesRegex(SystemExit, '1'):
                 setup.test_python_version()
 
diff --git a/scripts/third_party_size_check.py b/scripts/third_party_size_check.py
index f7c7f6265bf3..9cf12da35990 100644
--- a/scripts/third_party_size_check.py
+++ b/scripts/third_party_size_check.py
@@ -25,14 +25,8 @@
 import os
 import sys
 
-# TODO(#15567): This can be removed after Literal in utils.py is loaded
-# from typing instead of typing_extensions, this will be possible after
-# we migrate to Python 3.8.
-from scripts import common  # isort:skip pylint: disable=wrong-import-position, unused-import
-
-from core import utils  # isort:skip
-
-from typing import List  # isort:skip
+from core import utils
+from typing import List
 
 THIRD_PARTY_PATH = os.path.join(os.getcwd(), 'third_party')
 THIRD_PARTY_SIZE_LIMIT = 15000
diff --git a/stubs/threading/__init__.pyi b/stubs/threading/__init__.pyi
index 8ec4a97e6deb..9e9f79f3fe39 100644
--- a/stubs/threading/__init__.pyi
+++ b/stubs/threading/__init__.pyi
@@ -80,13 +80,9 @@ class Thread:
     def start(self) -> None: ...
     def run(self) -> None: ...
     def join(self, timeout: Optional[float] = ...) -> None: ...
-    if sys.version_info >= (3, 8):
-        @property
-        def native_id(self) -> Optional[int]: ...  # only available on some platforms
-
+    @property
+    def native_id(self) -> Optional[int]: ...  # only available on some platforms
     def is_alive(self) -> bool: ...
-    if sys.version_info < (3, 9):
-        def isAlive(self) -> bool: ...
 
 class _DummyThread(Thread):
     def __init__(self) -> None: ...