Profiles / #2
Failed Run of Oct 18, 15:53
Some tests got too few samples to explain their time.
Rerun with
pytest --flakytest-profile --flakytest-rate 1000.
Wall time
52.77 s
4 workers
Test time
2m 32s
sum of test durations
Tests
301
300 passed
· 1 failed
Profiler
py-spy
500 Hz ·
59,375 samples · Python 3.14.8 · flakytest 2026.0b1
Peak memory
673 MB
4 workers together
Where the time goes
Test time by category- Password hashing47.43 s
- Migrations39.98 s
- Libraries38.24 s
- Database12.22 s
- Mocking3.46 s
- DB schema3.19 s
- Imports3.10 s
- Templates2.16 s
- pytest915 ms
- Factories593 ms
- Unsampled358 ms
- App code146 ms
- Deep copies68 ms
- Waiting46 ms
- Test code35 ms
- Network34 ms
- Cache27 ms
- Logging16 ms
- Serialization11 ms
Session timeline
Other
3.49 s
Tests
2m 34s
Startup
7.27 s
Collection
3.79 s
Between tests
1.94 s
Session teardown
9 ms
Test phases
Setup 43.05 s
Call 1m 48s
Teardown 1.16 s
Fix next
Ranked by the time each fix saves per run
1
Use plain static file storage in tests
Static file storage/manifest handling costs 45.3s.
High
App code
45.34 s
per run
Fix: In test settings use STORAGES["staticfiles"] = {"BACKEND": "django.contrib.staticfiles.storage.StaticFilesStorage"} so templates don't need a manifest.
Details
Where:
- starter_packs/tests.py:840 test_api_formats · 1.24 s
- confs/tests.py:152 _assert_no_naive_warning · 1.15 s
- accounts/tests.py:550 assert_noindex · 1.07 s
- accounts/tests.py:555 assert_indexable · 998 ms
- starter_packs/tests.py:780 test_order_by · 974 ms
- starter_packs/tests.py:820 test_sort_select_avoids_inline_js · 900 ms
- accounts/views.py:428 index · 826 ms
- accounts/tests.py:536 test_developers_on_mastodon · 636 ms
- confs/tests.py:884 test_conference_with_pacific_with_date · 625 ms
- starter_packs/tests.py:197 test_not_owned_starter_pack · 556 ms
Most affected tests:
- starter_packs/tests.py::TestShareStarterPack::test_sort_select_avoids_inline_js
- confs/tests.py::TestConferencePage::test_conference_with_pacific_with_date
- accounts/tests.py::TestStaticPages::test_developers_on_mastodon
- confs/tests.py::TestMigratedLegacyConferences::test_djangoconafrica_page
- starter_packs/tests.py::TestShareStarterPack::test_non_discoverable_accounts
- starter_packs/tests.py::TestStarterPacks::test_index_page_language_filter
- starter_packs/tests.py::TestEditStarterPack::test_not_owned_starter_pack
- accounts/tests.py::TestAccountIndexRobots::test_single_facet_is_indexable
2
Use a fast password hasher in tests
47.4s (31% of test time) is spent hashing passwords. Slow hashing protects real passwords; in tests it only burns CPU.
High
Password hashing
45.06 s
per run
Fix: In your test settings set PASSWORD_HASHERS = ["django.contrib.auth.hashers.MD5PasswordHasher"] (currently PBKDF2PasswordHasher). Also replace self.client.login(username=…, password=…) with self.client.force_login(user), which skips password checks entirely: fedidevs/tests.py:63
Details
Only change the hasher in test settings. Tests that assert on a specific hash format need updating.
Where:
- confs/tests.py:1044 setUp · 8.94 s
- confs/tests.py:1175 setUp · 6.35 s
- confs/tests.py:1176 setUp · 5.77 s
- confs/tests.py:1371 setUp · 5.75 s
- confs/tests.py:1177 setUp · 5.45 s
- confs/tests.py:1372 setUp · 5.35 s
- confs/tests.py:1316 setUp · 3.65 s
- confs/tests.py:1317 setUp · 2.96 s
- fedidevs/tests.py:62 test_authenticated_html_is_private_and_keeps_csrf_header · 1.17 s
- fedidevs/tests.py:63 test_authenticated_html_is_private_and_keeps_csrf_header · 794 ms
Most affected tests:
- confs/tests.py::TestEditConference::test_owner_can_edit
- confs/tests.py::TestEditConference::test_other_user_forbidden_on_approved_conference
- confs/tests.py::TestEditConference::test_edit_does_not_change_slug
- confs/tests.py::TestEditConference::test_other_user_forbidden
- confs/tests.py::TestApproveConference::test_anonymous_sees_pending_banner_without_button
- confs/tests.py::TestApproveConference::test_staff_sees_approve_button_on_detail
- confs/tests.py::TestEditConference::test_owner_can_edit_after_approval
- confs/tests.py::TestConferenceApprovalVisibility::test_other_user_does_not_see_pending
3
Stop re-running migrations on every test run
Migrations take 40.0s per run, before the first test can start.
High
Migrations
35.98 s
per run
Fix: Run with --reuse-db (add it to addopts in pytest.ini/pyproject) so the test database survives between runs; pass --create-db when migrations change. If no test depends on data migrations, --nomigrations builds the schema straight from the models, which is faster still.
Details
CI should still build the database from scratch (no --reuse-db) so broken migrations are caught.
Where:
- confs/tests.py:432 _migrate · 2.48 s
- confs/migrations/0031_seed_conference_tags.py:14 seed_conference_tags · 934 ms
- confs/migrations/0033_remove_legacy_conference_tables.py:388 _get_or_create_conference · 177 ms
- confs/tests.py:430 _migrate · 172 ms
- confs/tests.py:412 _leaf_targets · 170 ms
- confs/migrations/0033_remove_legacy_conference_tables.py:214 _pk_batches · 157 ms
- confs/tests.py:431 _migrate · 145 ms
- confs/migrations/0033_remove_legacy_conference_tables.py:328 _refresh_account_counts · 77 ms
- confs/migrations/0033_remove_legacy_conference_tables.py:398 migrate_legacy_pair · 60 ms
- confs/migrations/0033_remove_legacy_conference_tables.py:360 _attach_lookups_and_tags · 58 ms
Most affected tests:
- confs/tests.py::TestConferencePage::test_conference_with_utc_with_date_no_posts
- accounts/tests.py::TestAccountIndexRobots::test_single_facet_is_indexable
- accounts/tests.py::TestSelectedInstance::test_invalid_selected_instance
- confs/tests.py::TestMigratedLegacyConferences::test_djangoconus_old_url_redirects
- confs/tests.py::TestLegacyConferenceDataMigration::test_copies_overlapping_legacy_rows_without_clobbering_existing_data
- confs/tests.py::TestLegacyConferenceDataMigration::test_drops_legacy_tables_when_uniques_are_mysql_style_indexes
4
Create shared test data in setUpTestData instead of setUp
setUp() runs before every test and takes 45.8s in total (password hashing 45.5s, db 271ms, factories 20ms) in 7 classes: TestPostAnnouncements (6 tests), TestFollowStarterPack (3 tests), TestConferenceApprovalVisibility (5 tests), TestApproveConference (6 tests).
High
Database
32.04 s
per run
Fix: Move object creation that tests only read from setUp() into `@classmethod def setUpTestData(cls)`: it runs once per class and each test still sees the original rows (TestCase rolls back to a savepoint).
Details
Since Django 3.2 attributes assigned in setUpTestData are deep-copied per test, so in-memory changes don't leak between tests. Keep objects a test modifies in the database (or re-fetches) as before.
Where:
- confs/tests.py:1044 setUp · 8.97 s
- confs/tests.py:1175 setUp · 6.37 s
- confs/tests.py:1176 setUp · 5.79 s
- confs/tests.py:1371 setUp · 5.76 s
- confs/tests.py:1177 setUp · 5.46 s
- confs/tests.py:1372 setUp · 5.36 s
- confs/tests.py:1316 setUp · 3.67 s
- confs/tests.py:1317 setUp · 2.96 s
- confs/tests.py:1295 setUp · 635 ms
- confs/tests.py:1296 setUp · 614 ms
Most affected tests:
- confs/tests.py::TestEditConference::test_owner_can_edit
- confs/tests.py::TestEditConference::test_other_user_forbidden_on_approved_conference
- confs/tests.py::TestEditConference::test_edit_does_not_change_slug
- confs/tests.py::TestEditConference::test_other_user_forbidden
- confs/tests.py::TestApproveConference::test_anonymous_sees_pending_banner_without_button
- confs/tests.py::TestApproveConference::test_staff_sees_approve_button_on_detail
- confs/tests.py::TestEditConference::test_owner_can_edit_after_approval
- confs/tests.py::TestConferenceApprovalVisibility::test_other_user_does_not_see_pending
5
Repeated queries (N+1) in the code under test
10 tests run the same query 10+ times, e.g. 45x in test_single_facet_is_indexable. N+1 queries slow the tests and production alike.
Medium
Database
13.40 s
per run
Fix: Django: fetch related rows in one query with select_related() for foreign keys and prefetch_related() for reverse/many-to-many relations, then lock the count in with assertNumQueries (or pytest-django's django_assert_num_queries).
Details
This changes application code, so it speeds up production too; the tests stay as they are.
- 45x in test_single_facet_is_indexable: SELECT "confs_conferencetag"."id", "confs_conferencetag"."name", "confs_conferencetag"."slug", "confs_conferencetag"."icon" FROM "confs_conferencetag" WHERE "confs_conferencetag"."slug" = %s LIMIT ? FOR UPDATE
- 45x in test_invalid_selected_instance: SELECT "confs_conferencetag"."id", "confs_conferencetag"."name", "confs_conferencetag"."slug", "confs_conferencetag"."icon" FROM "confs_conferencetag" WHERE "confs_conferencetag"."slug" = %s LIMIT ? FOR UPDATE
- 45x in test_djangoconus_old_url_redirects: SELECT "confs_conferencetag"."id", "confs_conferencetag"."name", "confs_conferencetag"."slug", "confs_conferencetag"."icon" FROM "confs_conferencetag" WHERE "confs_conferencetag"."slug" = %s LIMIT ? FOR UPDATE
- 45x in test_conference_with_utc_with_date_no_posts: SELECT "confs_conferencetag"."id", "confs_conferencetag"."name", "confs_conferencetag"."slug", "confs_conferencetag"."icon" FROM "confs_conferencetag" WHERE "confs_conferencetag"."slug" = %s LIMIT ? FOR UPDATE
- 44x in test_store_daily_stats: SELECT COUNT(*) AS "__count" FROM "accounts_accountlookup" WHERE UPPER("accounts_accountlookup"."language"::text) LIKE UPPER(%s)
Most affected tests:
- accounts/tests.py::TestAccountIndexRobots::test_single_facet_is_indexable
- accounts/tests.py::TestSelectedInstance::test_invalid_selected_instance
- confs/tests.py::TestMigratedLegacyConferences::test_djangoconus_old_url_redirects
- confs/tests.py::TestConferencePage::test_conference_with_utc_with_date_no_posts
- stats/tests.py::TestStats::test_store_daily_stats
- stats/tests.py::TestStats::test_store_daily_stats_with_accounts
- stats/tests.py::TestStats::test_posts_from_yesterday_are_updated
- accounts/tests.py::TestInstanceIndexingBridgy::test_follows_redirect_and_coerces_null_version
6
Make the test database server skip durability work
Tests spend 55.4s (36%) in the database. Test databases don't need to survive a crash, so the server can skip flushing to disk.
Medium
Database
11.08 s
per run
Fix: For a PostgreSQL test server (Docker/CI service) start it with -c fsync=off -c synchronous_commit=off -c full_page_writes=off, and put its data directory on tmpfs; for MySQL use --innodb-flush-log-at-trx-commit=0 --skip-log-bin. Never on a server with data you need.
Details
Only affects crash safety of the throwaway test server; query behaviour is identical.
Where:
- confs/tests.py:432 _migrate · 2.48 s
- starter_packs/tests.py:396 test_toggle_after_limit · 1.11 s
- confs/migrations/0031_seed_conference_tags.py:14 seed_conference_tags · 934 ms
- stats/models.py:20 store_daily_stats · 282 ms
- stats/models.py:12 store_daily_stats · 232 ms
- confs/migrations/0033_remove_legacy_conference_tables.py:388 _get_or_create_conference · 177 ms
- confs/tests.py:430 _migrate · 172 ms
- confs/tests.py:412 _leaf_targets · 170 ms
- starter_packs/views.py:729 share_starter_pack · 167 ms
- confs/migrations/0033_remove_legacy_conference_tables.py:214 _pk_batches · 157 ms
Most affected tests:
- accounts/tests.py::TestSelectedInstance::test_invalid_selected_instance
- confs/tests.py::TestConferencePage::test_conference_with_utc_with_date_no_posts
- accounts/tests.py::TestAccountIndexRobots::test_single_facet_is_indexable
- confs/tests.py::TestMigratedLegacyConferences::test_djangoconus_old_url_redirects
- confs/tests.py::TestLegacyConferenceDataMigration::test_copies_overlapping_legacy_rows_without_clobbering_existing_data
- confs/tests.py::TestLegacyConferenceDataMigration::test_drops_legacy_tables_when_uniques_are_mysql_style_indexes
- starter_packs/tests.py::TestToggleStarterPackAccount::test_toggle_after_limit
- mastodon_auth/tests.py::RegisterAppTests::test_raises_with_status_code_on_429
7
Disable django-debug-toolbar in tests
django-debug-toolbar is installed in the test settings and costs 8.7s.
Medium
App code
8.72 s
per run
Fix: Only add debug_toolbar to INSTALLED_APPS and MIDDLEWARE when not testing (e.g. `if DEBUG and not TESTING:`).
Details
Where:
- accounts/views.py:428 index · 826 ms
- confs/views.py:299 _conference_detail · 492 ms
- starter_packs/views.py:865 share_starter_pack · 382 ms
- confs/views.py:512 create_conference · 192 ms
- starter_packs/views.py:188 starter_packs · 185 ms
- starter_packs/views.py:729 share_starter_pack · 170 ms
- starter_packs/views.py:858 share_starter_pack · 145 ms
- accounts/views.py:28 __init__ · 145 ms
- confs/views.py:131 conferences · 137 ms
- accounts/templatetags/account_extras.py:27 render_language_emojis · 124 ms
Most affected tests:
- accounts/tests.py::TestSelectedInstance::test_invalid_selected_instance
- confs/tests.py::TestMigratedLegacyConferences::test_dotnetconf_page
- confs/tests.py::TestConferencePage::test_conference_with_utc_with_date_no_posts
- accounts/tests.py::TestAccountIndexRobots::test_single_facet_is_indexable
- fedidevs/tests.py::TestAnonymousCacheAndCsrf::test_anonymous_forms_work_after_csrf_bootstrap
- accounts/tests.py::TestSelectedInstance::test_selected_instance_through_session
- fedidevs/tests.py::TestAnonymousCacheAndCsrf::test_other_pages_keep_unknown_query_params
- accounts/tests.py::TestSelectedInstance::test_selected_instance
8
pytest takes a long time before the first test runs
Startup takes 7.3s and collection 3.8s on every run, even when you only run one test.
Low
Imports
4.42 s
per run
Fix: Set testpaths and norecursedirs (node_modules, .venv, build, docs) so pytest doesn't walk unrelated directories; move heavy imports out of module level in test files and conftest.py into fixtures; check `python -X importtime -m pytest --collect-only -q` for the slowest imports.
Details
- mastodon_auth/tests.py (1.0s)
- starter_packs/tests.py (207ms)
- accounts/tests.py (52ms)
- confs/tests.py (29ms)
- stats/tests.py (9ms)
- fedidevs/settings.py (1.9s)
- starter_packs/admin.py (1.3s)
- debug_toolbar/panels/sql/__init__.py (885ms)
9
Modules are imported while tests run
3.1s of test time is spent importing modules: whichever test imports a heavy module first pays for it, which makes that test look slow (and varies with test order).
Low
Imports
931 ms
per run
Fix: Find what is imported at the lines listed. Import heavy modules at the top of the test module or in conftest.py so the cost shows up once at collection, or avoid importing them in tests at all (e.g. stub the heavy dependency).
Details
Where:
- confs/views.py:299 _conference_detail · 152 ms
- mastodon_auth/forms.py:27 clean_instance · 120 ms
- confs/og_images.py:246 render_conference_og_image · 118 ms
- confs/tests.py:431 _migrate · 103 ms
- accounts/management/commands/indexer.py:81 handle · 91 ms
- confs/tests.py:875 test_conference_with_utc_with_date_no_posts · 81 ms
- confs/tests.py:412 _leaf_targets · 73 ms
- accounts/views.py:428 index · 65 ms
- starter_packs/splash_images.py:192 is_character_in_font · 39 ms
- accounts/tests.py:555 assert_indexable · 34 ms
Most affected tests:
- accounts/tests.py::TestSelectedInstance::test_invalid_selected_instance
- accounts/tests.py::TestAccountIndexRobots::test_single_facet_is_indexable
- confs/tests.py::TestMigratedLegacyConferences::test_djangoconus_old_url_redirects
- confs/tests.py::TestConferencePage::test_conference_with_utc_with_date_no_posts
- confs/tests.py::TestConferenceOgImage::test_management_command_renders_missing_and_skips_current
- confs/tests.py::TestLegacyConferenceDataMigration::test_drops_legacy_tables_when_uniques_are_mysql_style_indexes
- mastodon_auth/tests.py::MastodonLoginFormTests::test_cleans_instance_to_ascii_hostname
- confs/tests.py::TestLegacyConferenceDataMigration::test_copies_overlapping_legacy_rows_without_clobbering_existing_data
Tests
201–301 of 301, slowest first · click a column to sort this page
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Memory
Busiest worker peaked at 207 MB; all 4 together at about 673 MB| Worker | Tests | Peak | Grew by |
|---|---|---|---|
| gw0 | 101 | 202 MB | 57 MB |
| gw1 | 118 | 195 MB | 54 MB |
| gw2 | 49 | 207 MB | 35 MB |
| gw3 | 33 | 178 MB | 40 MB |
Slowest fixtures
Exact setup time across the session| Fixture | Scope | Calls | Total |
|---|---|---|---|
| _django_setup_unittest | class | 75 | 39.77 s |
| django_db_setup | session | 4 | 39.69 s |
| _unittest_setUpClass_fixture_TestSelectedInstance | class | 1 | 290 ms |
| _unittest_setUpClass_fixture_TestShareStarterPack | class | 2 | 208 ms |
| _unittest_setUpClass_fixture_TestEditStarterPackAccounts | class | 2 | 206 ms |
| _unittest_setUpClass_fixture_TestConferencePage | class | 2 | 192 ms |
| _unittest_setUpClass_fixture_TestPinAccountInStarterPack | class | 2 | 153 ms |
| _unittest_setUpClass_fixture_TestOwnerManagement | class | 2 | 122 ms |
| _unittest_setUpClass_fixture_TestFollowStarterPack | class | 2 | 108 ms |
| _unittest_setUpClass_fixture_TestFollowBg | class | 1 | 77 ms |
| _unittest_setUpClass_fixture_TestWebfingerBackfill | class | 1 | 73 ms |
| _django_isolate_apps | function | 301 | 65 ms |
| _unittest_setUpClass_fixture_TestStarterPacks | class | 1 | 62 ms |
| _unittest_setUpClass_fixture_TestRemoteFollowStarterPack | class | 2 | 61 ms |
| _unittest_setUpClass_fixture_TestAddAccountsSearch | class | 1 | 60 ms |