Speed up semaphore tests

distributed/tests/test_semaphore.py

@@ -126,11 +126,11 @@ async def test_async_ctx(s, a, b):
     assert await sem.acquire()
 
 
-@pytest.mark.slow
 def test_worker_dies():
     with cluster(
         config={
-            "distributed.scheduler.locks.lease-timeout": "0.1s",
+            "distributed.scheduler.locks.lease-timeout": "50ms",
+            "distributed.scheduler.locks.lease-validation-interval": "10ms",
         }
     ) as (scheduler, workers):
         with Client(scheduler["address"]) as client:
@@ -188,9 +188,8 @@ def f(x, release=True):
     assert result.count(False) == 9
 
 
-@pytest.mark.slow
-@gen_cluster(client=True, timeout=120)
-async def test_close_async(c, s, a, b):
+@gen_cluster(client=True, nthreads=[("", 1)])
+async def test_close_async(c, s, a):
     sem = await Semaphore(name="test")
 
     assert await sem.acquire()
@@ -209,7 +208,7 @@ async def test_close_async(c, s, a, b):
     assert await sem2.acquire()
 
     def f(sem_):
-        return sem_.acquire()
+        sem_.acquire(timeout="0.5s")
 
     semaphore_object = s.extensions["semaphores"]
     fire_and_forget(c.submit(f, sem_=sem2))
@@ -514,7 +513,7 @@ def access_limited(val, sem):
                     assert len(protected_resource) == 0
                     protected_resource.append(val)
                     # Interact with the DB
-                    time.sleep(0.2)
+                    time.sleep(0.01)
                     protected_resource.remove(val)
 
             client.gather(client.map(access_limited, range(10), sem=sem))