CI test the future loky-3.3.0 branch

CHANGES.rst

@@ -34,8 +34,9 @@ Development version
 
 - Vendor cloudpickle 2.2.0 which adds support for PyPy 3.8+.
 
-- Vendor loky 3.2.0 which fixes a bug with leaking processes in case of
-  nested loky parallel calls.
+- Vendor loky 3.3.0 which fixes a bug with leaking processes in case of
+  nested loky parallel calls and more reliability spawn the correct
+  number of reusable workers.
 
 Release 1.1.0
 --------------

azure-pipelines.yml

@@ -55,15 +55,15 @@ jobs:
         # dependencies.
         imageName: 'ubuntu-latest'
         PYTHON_VERSION: "3.10"
-        EXTRA_CONDA_PACKAGES: "numpy=1.22 distributed=2022.2.0"
+        EXTRA_CONDA_PACKAGES: "numpy=1.23 distributed=2022.2.0"
       linux_py37_distributed:
         imageName: 'ubuntu-latest'
         PYTHON_VERSION: "3.7"
         EXTRA_CONDA_PACKAGES: "numpy=1.15 distributed=2.13"
       linux_py310_cython:
         imageName: 'ubuntu-latest'
         PYTHON_VERSION: "3.10"
-        EXTRA_CONDA_PACKAGES: "numpy=1.22"
+        EXTRA_CONDA_PACKAGES: "numpy=1.23"
         CYTHON: "true"
       linux_py37_no_multiprocessing_no_lzma:
         imageName: 'ubuntu-latest'
@@ -78,12 +78,12 @@ jobs:
       windows_py310:
         imageName: "windows-latest"
         PYTHON_VERSION: "3.10"
-        EXTRA_CONDA_PACKAGES: "numpy=1.22"
+        EXTRA_CONDA_PACKAGES: "numpy=1.23"
 
       macos_py310:
         imageName: "macos-latest"
         PYTHON_VERSION: "3.10"
-        EXTRA_CONDA_PACKAGES: "numpy=1.22"
+        EXTRA_CONDA_PACKAGES: "numpy=1.23"
       macos_py37_no_numpy:
         imageName: "macos-latest"
         PYTHON_VERSION: "3.7"

joblib/externals/loky/__init__.py

@@ -29,4 +29,4 @@
            "wrap_non_picklable_objects", "set_loky_pickler"]
 
 
-__version__ = '3.2.0'
+__version__ = '3.3.0'

joblib/externals/loky/process_executor.py

@@ -678,9 +678,12 @@ def process_result_item(self, result_item):
             with self.processes_management_lock:
                 p = self.processes.pop(result_item, None)
 
-            # p can be None is the executor is concurrently shutting down.
+            # p can be None if the executor is concurrently shutting down.
             if p is not None:
                 p._worker_exit_lock.release()
+                mp.util.debug(
+                    f"joining {p.name} when processing {p.pid} as result_item"
+                )
                 p.join()
                 del p
 
@@ -699,7 +702,8 @@ def process_result_item(self, result_item):
                         "executor. This can be caused by a too short worker "
                         "timeout or by a memory leak.", UserWarning
                     )
-                    executor._adjust_process_count()
+                    with executor._processes_management_lock:
+                        executor._adjust_process_count()
                     executor = None
         else:
             # Received a _ResultItem so mark the future as completed.
@@ -837,15 +841,23 @@ def join_executor_internals(self):
             self.thread_wakeup.close()
 
         # If .join() is not called on the created processes then
-        # some ctx.Queue methods may deadlock on Mac OS X.
-        active_processes = list(self.processes.values())
-        mp.util.debug(f"joining {len(active_processes)} processes")
-        for p in active_processes:
-            mp.util.debug(f"joining process {p.name}")
-            p.join()
+        # some ctx.Queue methods may deadlock on macOS.
+        with self.processes_management_lock:
+            mp.util.debug(f"joining {len(self.processes)} processes")
+            n_joined_processes = 0
+            while True:
+                try:
+                    pid, p = self.processes.popitem()
+                    mp.util.debug(f"joining process {p.name} with pid {pid}")
+                    p.join()
+                    n_joined_processes += 1
+                except KeyError:
+                    break
 
-        mp.util.debug("executor management thread clean shutdown of worker "
-                      f"processes: {active_processes}")
+            mp.util.debug(
+                "executor management thread clean shutdown of "
+                f"{n_joined_processes} workers"
+            )
 
     def get_n_children_alive(self):
         # This is an upper bound on the number of children alive.
@@ -1082,7 +1094,7 @@ def _start_executor_manager_thread(self):
                         _python_exit)
 
     def _adjust_process_count(self):
-        for _ in range(len(self._processes), self._max_workers):
+        while len(self._processes) < self._max_workers:
             worker_exit_lock = self._context.BoundedSemaphore(1)
             args = (self._call_queue, self._result_queue, self._initializer,
                     self._initargs, self._processes_management_lock,
@@ -1098,7 +1110,10 @@ def _adjust_process_count(self):
             p._worker_exit_lock = worker_exit_lock
             p.start()
             self._processes[p.pid] = p
-        mp.util.debug(f'Adjust process count : {self._processes}')
+        mp.util.debug(
+            f"Adjusted process count to {self._max_workers}: "
+            f"{[(p.name, pid) for pid, p in self._processes.items()]}"
+        )
 
     def _ensure_executor_running(self):
         """ensures all workers and management thread are running

joblib/test/test_memmapping.py

@@ -613,29 +613,25 @@ def test_many_parallel_calls_on_same_object(backend):
                         delayed(return_slice_of_data)(data, 0, 20)
                         for _ in range(10)
                     )
-                slice_of_data = Parallel(
-                    n_jobs=2, max_nbytes=1, backend='{b}')(
-                        delayed(return_slice_of_data)(data, 0, 20)
-                        for _ in range(10)
-                    )
     '''.format(b=backend)
-
-    for _ in range(3):
-        env = os.environ.copy()
-        env['PYTHONPATH'] = os.path.dirname(__file__)
-        p = subprocess.Popen([sys.executable, '-c', cmd],
-                             stderr=subprocess.PIPE,
-                             stdout=subprocess.PIPE, env=env)
-        p.wait()
-        out, err = p.communicate()
-        assert p.returncode == 0, err
-        assert out == b''
-        if sys.version_info[:3] not in [(3, 8, 0), (3, 8, 1)]:
-            # In early versions of Python 3.8, a reference leak
-            # https://github.com/cloudpipe/cloudpickle/issues/327, holds
-            # references to pickled objects, generating race condition during
-            # cleanup finalizers of joblib and noisy resource_tracker outputs.
-            assert b'resource_tracker' not in err
+    env = os.environ.copy()
+    env['PYTHONPATH'] = os.path.dirname(__file__)
+    p = subprocess.Popen(
+        [sys.executable, '-c', cmd],
+        stderr=subprocess.PIPE,
+        stdout=subprocess.PIPE,
+        env=env,
+    )
+    p.wait()
+    out, err = p.communicate()
+    assert p.returncode == 0, err
+    assert out == b''
+    if sys.version_info[:3] not in [(3, 8, 0), (3, 8, 1)]:
+        # In early versions of Python 3.8, a reference leak
+        # https://github.com/cloudpipe/cloudpickle/issues/327, holds
+        # references to pickled objects, generating race condition during
+        # cleanup finalizers of joblib and noisy resource_tracker outputs.
+        assert b'resource_tracker' not in err
 
 
 @with_numpy