gevent: Adds autoscaler support to gevent pool. Closes #599.

celery/concurrency/gevent.py

@@ -109,3 +109,16 @@ def on_apply(self, target, args=None, kwargs=None, callback=None,
             accept_callback=None, **_):
         return self._pool.spawn(apply_target, target, args, kwargs,
                                 callback, accept_callback)
+    def grow(self, n=1):
+        self._pool._semaphore.counter += n
+        self._pool.size += n
+        return None
+
+    def shrink(self, n=1):
+        self._pool._semaphore.counter -= n
+        self._pool.size -= n
+        return None
+
+    @property
+    def num_processes(self):
+        return len(self._pool)

celery/tests/test_concurrency/test_concurrency_gevent.py

@@ -0,0 +1,53 @@
+from __future__ import absolute_import
+
+from nose import SkipTest
+
+from celery.concurrency.gevent import TaskPool
+from celery.tests.utils import unittest
+
+
+class GeventCase(unittest.TestCase):
+
+    def setUp(self):
+        try:
+            self.gevent = __import__("gevent")
+        except ImportError:
+            raise SkipTest(
+                "gevent not installed, skipping related tests.")
+
+
+class test_TaskPool(GeventCase):
+
+    def test_grow(self):
+        pool = TaskPool(10)
+        pool.start()
+        self.assertEqual(pool._pool.size, 10)
+        pool.grow()
+        self.assertEqual(pool._pool.size, 11)
+
+    def test_grow_many(self):
+        pool = TaskPool(10)
+        pool.start()
+        self.assertEqual(pool._pool.size, 10)
+        pool.grow(2)
+        self.assertEqual(pool._pool.size, 12)
+
+    def test_shrink(self):
+        pool = TaskPool(10)
+        pool.start()
+        self.assertEqual(pool._pool.size, 10)
+        pool.shrink()
+        self.assertEqual(pool._pool.size, 9)
+
+    def test_shrink_many(self):
+        pool = TaskPool(10)
+        pool.start()
+        self.assertEqual(pool._pool.size, 10)
+        pool.shrink(2)
+        self.assertEqual(pool._pool.size, 8)
+
+    def test_num_processes(self):
+        pool = TaskPool(10)
+        pool.start()
+        pool.apply_async(lambda x: x, (2, ), {})
+        self.assertEqual(pool.num_processes, 1)