diff --git a/groupConnectivity.pyx b/groupConnectivity.pyx
index 007c5deaee2ddd6f2ae1bdb3e39ce1f5b4057fad..bb11b0d8036b118f07035cd6fc6d03227faadbb6 100644
--- a/groupConnectivity.pyx
+++ b/groupConnectivity.pyx
@@ -139,7 +139,7 @@ def subdivisionIterator(G, edges = None):
 
 def generateSubdivisions(file, G, edges = None,
                          function = lambda H: H.graph6_string(),
-                         parallel = 0):
+                         parallel = 0, chunksize = 1):
   f = open(file, 'w+')
   f.write("# Subdivisions of edges '%s' of graph '%s' (%s)\n" %
           (edges, G.graph6_string(), G))
@@ -147,7 +147,8 @@ def generateSubdivisions(file, G, edges = None,
   if parallel == 0:
     iterator = map(function, subdivisionIterator(G, edges))
   else:
-    iterator = parmap(function, subdivisionIterator(G, edges), parallel)
+    iterator = parmap(function, subdivisionIterator(G, edges),
+                      nprocs = parallel, chunksize = chunksize)
 
   for line in iterator:
     f.write(line)
diff --git a/parmap.py b/parmap.py
index 040e8ddce735f1e3a5982bb953dbe3a146b83505..dcb8521873d82301a1a98f8c04b5e3c6e14ae27c 100644
--- a/parmap.py
+++ b/parmap.py
@@ -2,10 +2,21 @@
 # http://stackoverflow.com/a/16071616
 
 import multiprocessing
+from itertools import chain
 
-def producer_fun(X, q_in, q_control, nprocs):
+def chunkme(X, chunksize):
+  chunk = []
+  for x in X:
+    if len(chunk) >= chunksize:
+      yield chunk
+      chunk = []
+    chunk.append(x)
+  if len(chunk):
+    yield chunk
+
+def producer_fun(X, q_in, q_control, nprocs, chunksize):
   sent = 0
-  for i, x in enumerate(X):
+  for i, x in enumerate(chunkme(X, chunksize)):
     q_in.put((i, x))
     sent += 1
 
@@ -16,12 +27,12 @@ def producer_fun(X, q_in, q_control, nprocs):
 
 def worker_fun(f, q_in, q_out):
     while True:
-        i, x = q_in.get()
+        i, chunk = q_in.get()
         if i is None:
             break
-        q_out.put((i, f(x)))
+        q_out.put((i, [ f(x) for x in chunk ]))
 
-def parmap(f, X, nprocs = None):
+def parmap(f, X, nprocs = None, chunksize = 1):
     if nprocs is None:
       nprocs = multiprocessing.cpu_count()
 
@@ -34,7 +45,7 @@ def parmap(f, X, nprocs = None):
 
     proc.append(multiprocessing.Process(
       target = producer_fun,
-      args = (X, q_in, q_out, nprocs)
+      args = (X, q_in, q_out, nprocs, chunksize)
     ))
 
     for p in proc:
@@ -57,5 +68,5 @@ def parmap(f, X, nprocs = None):
     for p in proc:
       p.join()
 
-    return [ ret[i] for i in range(len(ret)) ]
+    return chain.from_iterable([ ret[i] for i in range(len(ret)) ])