Fix flaky test_call_stack_future (#9277)

Author: crusaderky

distributed/tests/test_client.py

@@ -28,7 +28,6 @@
 from dataclasses import dataclass
 from functools import partial
 from operator import add
-from threading import Semaphore
 from time import sleep
 from typing import Any
 from unittest import mock
@@ -37,7 +36,7 @@
 import pytest
 import yaml
 from packaging.version import parse as parse_version
-from tlz import concat, first, identity, isdistinct, merge, pluck, valmap
+from tlz import concat, identity, isdistinct, merge, pluck, valmap
 
 import dask
 import dask.bag as db
@@ -3849,7 +3848,7 @@ def test_open_close_many_workers(loop, worker, count, repeat):
     with cluster(nworkers=0, active_rpc_timeout=2) as (s, _):
         gc.collect()
         before = proc.num_fds()
-        done = Semaphore(0)
+        done = threading.Semaphore(0)
         running = weakref.WeakKeyDictionary()
         workers = set()
         status = True
@@ -5409,63 +5408,43 @@ def test_quiet_quit_when_cluster_leaves(loop_in_thread):
         assert not text
 
 
-@gen_cluster([("127.0.0.1", 4)] * 2, client=True)
-async def test_call_stack_future(c, s, a, b):
-    x = c.submit(slowdec, 1, delay=0.5)
-    future = c.submit(slowinc, 1, delay=0.5)
-    await asyncio.sleep(0.1)
-    results = await asyncio.gather(
-        c.call_stack(future), c.call_stack(keys=[future.key])
-    )
-    assert all(list(first(result.values())) == [future.key] for result in results)
-    assert results[0] == results[1]
-    result = results[0]
-    ts = a.state.tasks.get(future.key)
-    if ts is not None and ts.state == "executing":
-        w = a
-    else:
-        w = b
+@gen_cluster(client=True)
+async def test_call_stack(c, s, a, b):
+    e1, e2, e3, ew = Event(), Event(), Event(), Event()
 
-    assert list(result) == [w.address]
-    assert list(result[w.address]) == [future.key]
-    assert "slowinc" in str(result)
-    assert "slowdec" not in str(result)
+    def f(es: Event, ew: Event) -> None:
+        es.set()
+        ew.wait()
 
+    f1 = c.submit(f, e1, ew, key="f1", workers=[a.address])
+    f2 = c.submit(f, e2, ew, key="f2", workers=[b.address])
+    d3 = c.persist(delayed(f)(e3, ew, dask_key_name="d3"), workers=[b.address])
+    await e1.wait()
+    await e2.wait()
+    await e3.wait()
 
-@gen_cluster([("127.0.0.1", 4)] * 2, client=True)
-async def test_call_stack_all(c, s, a, b):
-    future = c.submit(slowinc, 1, delay=0.8)
-    while not a.state.executing_count and not b.state.executing_count:
-        await asyncio.sleep(0.01)
-    result = await c.call_stack()
-    w = a if a.state.executing_count else b
-    assert list(result) == [w.address]
-    assert list(result[w.address]) == [future.key]
-    assert "slowinc" in str(result)
+    # Test future or keys
+    r1a = await c.call_stack(f1)
+    r1b = await c.call_stack([f1])
+    r1c = await c.call_stack(keys=[f1.key])
 
+    assert r1a == r1b == r1c
+    assert r1a.keys() == {a.address}
+    assert r1a[a.address].keys() == {"f1"}
+    assert any("event.py" in frame for frame in r1a[a.address]["f1"])
 
-@gen_cluster([("127.0.0.1", 4)] * 2, client=True)
-async def test_call_stack_collections(c, s, a, b):
-    pytest.importorskip("numpy")
-    da = pytest.importorskip("dask.array")
-
-    x = c.persist(da.random.random(100, chunks=(10,)).map_blocks(slowinc, delay=0.5))
-    while not a.state.executing_count and not b.state.executing_count:
-        await asyncio.sleep(0.001)
-    result = await c.call_stack(x)
-    assert result
+    # test collection
+    r3 = await c.call_stack(d3)
+    assert r3.keys() == {b.address}
+    assert r3[b.address].keys() == {"d3"}
 
+    # test all
+    r4 = await c.call_stack()
+    assert r4.keys() == {a.address, b.address}
+    assert r4[a.address].keys() == {"f1"}
+    assert r4[b.address].keys() == {"f2", "d3"}
 
-@gen_cluster([("127.0.0.1", 4)] * 2, client=True)
-async def test_call_stack_collections_all(c, s, a, b):
-    pytest.importorskip("numpy")
-    da = pytest.importorskip("dask.array")
-
-    x = c.persist(da.random.random(100, chunks=(10,)).map_blocks(slowinc, delay=0.5))
-    while not a.state.executing_count and not b.state.executing_count:
-        await asyncio.sleep(0.001)
-    result = await c.call_stack()
-    assert result
+    await ew.set()
 
 
 @pytest.mark.skipif(sys.version_info.minor == 11, reason="Profiler disabled")