Halve CI runtime! (#5074)

Author: crusaderky

.github/workflows/tests.yaml

@@ -18,6 +18,8 @@ jobs:
       matrix:
         os: [ubuntu-latest, windows-latest, macos-latest]
         python-version: ["3.7", "3.8", "3.9"]
+        # Cherry-pick test modules to split the overall runtime roughly in half
+        partition: [ci1, not ci1]
 
         # Uncomment to stress-test the test suite for random failures.
         # Must also change env.TEST_ID below.
@@ -113,7 +115,7 @@ jobs:
           fi
           source continuous_integration/scripts/set_ulimit.sh
 
-          pytest distributed -m "not avoid_ci" --runslow \
+          pytest distributed -m "not avoid_ci and ${{ matrix.partition }}" --runslow \
             --junitxml reports/pytest.xml -o junit_suite_name=$TEST_ID
 
       # - name: Debug with tmate on failure

distributed/tests/test_client.py

@@ -95,6 +95,8 @@
     wait_for,
 )
 
+pytestmark = pytest.mark.ci1
+
 
 @gen_cluster(client=True)
 async def test_submit(c, s, a, b):

distributed/tests/test_failed_workers.py

@@ -26,6 +26,8 @@
     slowinc,
 )
 
+pytestmark = pytest.mark.ci1
+
 
 def test_submit_after_failed_worker_sync(loop):
     with cluster() as (s, [a, b]):

distributed/tests/test_nanny.py

@@ -26,6 +26,8 @@
 from distributed.utils import TimeoutError, parse_ports, tmpfile
 from distributed.utils_test import captured_logger, gen_cluster, gen_test, inc
 
+pytestmark = pytest.mark.ci1
+
 
 # FIXME why does this leave behind unclosed Comm objects?
 @gen_cluster(nthreads=[], allow_unclosed=True)

distributed/tests/test_scheduler.py

@@ -53,6 +53,8 @@
 else:
     import pickle
 
+pytestmark = pytest.mark.ci1
+
 
 alice = "alice:1234"
 bob = "bob:1234"

distributed/tests/test_steal.py

@@ -28,6 +28,8 @@
     slowinc,
 )
 
+pytestmark = pytest.mark.ci1
+
 # Most tests here are timing-dependent
 setup_module = nodebug_setup_module
 teardown_module = nodebug_teardown_module

distributed/tests/test_worker.py

@@ -51,6 +51,8 @@
 )
 from distributed.worker import Worker, error_message, logger, parse_memory_limit
 
+pytestmark = pytest.mark.ci1
+
 
 @pytest.mark.asyncio
 async def test_worker_nthreads(cleanup):

setup.cfg

@@ -47,8 +47,9 @@ filterwarnings =
     error:Since distributed.*:PendingDeprecationWarning
 minversion = 4
 markers =
-    slow: marks tests as slow (deselect with '-m "not slow"')
-    avoid_ci: marks tests as flaky on CI on all OSs
+    ci1: marks tests as belonging to 1 out of 2 partitions to run on CI ('-m "not ci1"' for second partition)
+    slow: marks tests as slow (deselected by default; select with '--runslow')
+    avoid_ci: marks tests as flaky or broken on CI on all OSs
     ipython: marks tests as exercising IPython
     gpu: marks tests we want to run on GPUs