From 99c19e1539aabb8053ee9221f62744bf76d63737 Mon Sep 17 00:00:00 2001
From: Tom Clegg <tclegg@veritasgenetics.com>
Date: Fri, 18 Aug 2017 15:43:49 -0400
Subject: [PATCH] 12134: Minimize multiprocessing worker startups.

Arvados-DCO-1.1-Signed-off-by: Tom Clegg <tclegg@veritasgenetics.com>
---
 services/fuse/tests/integration_test.py | 20 ++++++++++++--------
 services/fuse/tests/mount_test_base.py  |  6 +++---
 services/fuse/tests/test_exec.py        |  7 +++----
 3 files changed, 18 insertions(+), 15 deletions(-)

diff --git a/services/fuse/tests/integration_test.py b/services/fuse/tests/integration_test.py
index 6a0c5de899..3c11fa2920 100644
--- a/services/fuse/tests/integration_test.py
+++ b/services/fuse/tests/integration_test.py
@@ -17,12 +17,8 @@ import sys
 import tempfile
 import unittest
 
-_pool = None
-
-
 @atexit.register
 def _pool_cleanup():
-    global _pool
     if _pool is None:
         return
     _pool.close()
@@ -36,6 +32,17 @@ def wrap_static_test_method(modName, clsName, funcName, args, kwargs):
     Test().runTest(*args, **kwargs)
 
 
+# To avoid Python's threading+multiprocessing=deadlock problems, we
+# use a single global pool with maxtasksperchild=None for the entire
+# test suite.
+_pool = None
+def workerPool():
+    global _pool
+    if _pool is None:
+        _pool = multiprocessing.Pool(processes=1, maxtasksperchild=None)
+    return _pool
+
+
 class IntegrationTest(unittest.TestCase):
     def pool_test(self, *args, **kwargs):
         """Run a static method as a unit test, in a different process.
@@ -43,13 +50,10 @@ class IntegrationTest(unittest.TestCase):
         If called by method 'foobar', the static method '_foobar' of
         the same class will be called in the other process.
         """
-        global _pool
-        if _pool is None:
-            _pool = multiprocessing.Pool(1, maxtasksperchild=1)
         modName = inspect.getmodule(self).__name__
         clsName = self.__class__.__name__
         funcName = inspect.currentframe().f_back.f_code.co_name
-        _pool.apply(
+        workerPool().apply(
             wrap_static_test_method,
             (modName, clsName, '_'+funcName, args, kwargs))
 
diff --git a/services/fuse/tests/mount_test_base.py b/services/fuse/tests/mount_test_base.py
index 8518d8bbea..d476fc771b 100644
--- a/services/fuse/tests/mount_test_base.py
+++ b/services/fuse/tests/mount_test_base.py
@@ -21,6 +21,8 @@ import unittest
 
 logger = logging.getLogger('arvados.arv-mount')
 
+from .integration_test import workerPool
+
 class MountTestBase(unittest.TestCase):
     def setUp(self, api=None, local_store=True):
         # The underlying C implementation of open() makes a fstat() syscall
@@ -30,8 +32,8 @@ class MountTestBase(unittest.TestCase):
         # deadlocks.  The workaround is to run some of our test code in a
         # separate process.  Forturnately the multiprocessing module makes this
         # relatively easy.
-        self.pool = multiprocessing.Pool(1)
 
+        self.pool = workerPool()
         if local_store:
             self.keeptmp = tempfile.mkdtemp()
             os.environ['KEEP_LOCAL_STORE'] = self.keeptmp
@@ -89,8 +91,6 @@ class MountTestBase(unittest.TestCase):
             shutil.rmtree(self.keeptmp)
             os.environ.pop('KEEP_LOCAL_STORE')
         run_test_server.reset()
-        self.pool.close()
-        self.pool.join()
 
     def assertDirContents(self, subdir, expect_content):
         path = self.mounttmp
diff --git a/services/fuse/tests/test_exec.py b/services/fuse/tests/test_exec.py
index 85cb5e4698..ab6e13136b 100644
--- a/services/fuse/tests/test_exec.py
+++ b/services/fuse/tests/test_exec.py
@@ -10,6 +10,8 @@ import run_test_server
 import tempfile
 import unittest
 
+from .integration_test import workerPool
+
 try:
     from shlex import quote
 except:
@@ -44,16 +46,13 @@ class ExecMode(unittest.TestCase):
     def setUp(self):
         self.mnt = tempfile.mkdtemp()
         _, self.okfile = tempfile.mkstemp()
-        self.pool = multiprocessing.Pool(1)
 
     def tearDown(self):
-        self.pool.terminate()
-        self.pool.join()
         os.rmdir(self.mnt)
         os.unlink(self.okfile)
 
     def test_exec(self):
-        self.pool.apply(try_exec, (self.mnt, [
+        workerPool().apply(try_exec, (self.mnt, [
             'sh', '-c',
             'echo -n foo >{}; cp {} {}'.format(
                 quote(os.path.join(self.mnt, 'zzz', 'foo.txt')),
-- 
2.30.2