[gegl/threaded-base-classes: 10/22] operation-composer3: bail earlier on 0x0 roi

[Øyvind Kolås <ok src gnome org>]

commit 3fd633552f41ab37cfd1f895bdabbebc7d52f3fa
Author: Øyvind Kolås <pippin gimp org>
Date:   Tue Jun 24 05:42:51 2014 +0200

    operation-composer3: bail earlier on 0x0 roi

 gegl/operation/gegl-operation-composer3.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)
---
diff --git a/gegl/operation/gegl-operation-composer3.c b/gegl/operation/gegl-operation-composer3.c
index d9f5baa..08e0f82 100644
--- a/gegl/operation/gegl-operation-composer3.c
+++ b/gegl/operation/gegl-operation-composer3.c
@@ -192,11 +192,11 @@ gegl_operation_composer3_process (GeglOperation        *operation,
       aux != NULL ||
       aux2 != NULL)
     {
+      gint threads = gegl_config ()->threads;
       op_class->parallelize = 1;
-      if (op_class->parallelize && result->width * result->height > 64*64)
+      if (threads > 1 && op_class->parallelize && result->width * result->height > 64*64)
       {
         GThreadPool *pool = thread_pool ();
-        gint threads = gegl_config ()->threads;
         ThreadData thread_data[GEGL_MAX_THREADS];
         gint pending = threads;