Podder now runs with an associated thread pool.

This allows podder to parallelize requests to docker.

Change-Id: Iacae80a63bcd68ef7b471d63dbb41b7314d3af20
diff --git a/podder/main.py b/podder/main.py
index d02fc63..412ae58 100755
--- a/podder/main.py
+++ b/podder/main.py
@@ -35,7 +35,8 @@
     instance_id=os.environ.get('INSTANCE_ID', os.environ.get('HOSTNAME', '1')),
     internal_host_address=os.environ.get('INTERNAL_HOST_ADDRESS',
                                          get_my_primary_local_ipv4()),
-    work_dir=os.environ.get('WORK_DIR', '/tmp/podder')
+    work_dir=os.environ.get('WORK_DIR', '/tmp/podder'),
+    threads=os.environ.get('PODDER_THREADS', 5)
 )
 
 def parse_args():
@@ -103,6 +104,14 @@
                         action='count',
                         help=_help)
 
+    _help = 'Number of events to handle in parallel'
+    parser.add_argument('-e', '--events-in-parallel',
+                        dest='threads',
+                        type=int,
+                        default=defs['threads'],
+                        action='store',
+                        help=_help)
+
 
     args = parser.parse_args()