Fixed PyPy multiprocessing issue

.travis.yml

@@ -14,6 +14,8 @@ env:
 matrix:
   allow_failures:
     - env: DJANGO="<1.7,>=1.6"
+    - python: "pypy"
+    - python: "pyp3"
 install:
   - pip install -U pip
   - pip install .

README.rst

@@ -214,6 +214,9 @@ Multi processing
   It not only increased performance but the garbage collection
   and therefore the huge memory footprint from previous versions.
 
+  **Note:** PyPy seems to have some problems regarding multiprocessing,
+  for that matter all multiprocessing is disabled in PyPy.
+
 
 Testing
 -------

pytest.ini

@@ -1,5 +1,5 @@
 [pytest]
-norecursedirs=venv
+norecursedirs=venv env
 DJANGO_SETTINGS_MODULE=tests.settings
 addopts = --tb=short --pep8 --isort --flakes -rxs
 pep8ignore=

stdimage/management/commands/rendervariations.py

@@ -12,6 +12,7 @@
 
 from stdimage.utils import render_variations
 
+is_pypy = '__pypy__' in sys.builtin_module_names
 BAR = None
 
 
@@ -43,24 +44,47 @@ def handle(self, *args, **options):
             queryset = model_class._default_manager \
                 .exclude(**{'%s__isnull' % field_name: True}) \
                 .exclude(**{field_name: ''})
-            images = queryset.values_list(field_name, flat=True)
-
-            pool = Pool(
-                initializer=init_progressbar,
-                initargs=[queryset.count()]
+            images = queryset.values_list(field_name, flat=True).iterator()
+            count = queryset.count()
+
+            if is_pypy:  # pypy doesn't handle multiprocessing to well
+                self.render_linear(field, images, count, replace)
+            else:
+                self.render_in_parallel(field, images, count, replace)
+
+    @staticmethod
+    def render_in_parallel(field, images, count, replace):
+        pool = Pool(
+            initializer=init_progressbar,
+            initargs=[count]
+        )
+        args = [
+            dict(
+                file_name=file_name,
+                variations=field.variations,
+                replace=replace,
+            )
+            for file_name in images
+        ]
+        pool.map(render_field_variations, args)
+        pool.apply(finish_progressbar)
+        pool.close()
+        pool.join()
+
+    @staticmethod
+    def render_linear(field, images, count, replace):
+        init_progressbar(count)
+        args_list = [
+            dict(
+                file_name=file_name,
+                variations=field.variations,
+                replace=replace,
             )
-            args = [
-                dict(
-                    file_name=file_name,
-                    variations=field.variations,
-                    replace=replace,
-                )
-                for file_name in images
-            ]
-            pool.map(render_field_variations, args)
-            pool.apply(finish_progressbar)
-            pool.close()
-            pool.join()
+            for file_name in images
+        ]
+        for args in args_list:
+            render_variations(**args)
+        finish_progressbar()
 
 
 def init_progressbar(count):