diff --git a/ipc_benchmark.py b/ipc_benchmark.py
index 24b962f..5c24bde 100755
--- a/ipc_benchmark.py
+++ b/ipc_benchmark.py
@@ -103,6 +103,7 @@ def remove(self):
             self.ptr = None
         if self.shmid and self.is_creator:
             shmctl(self.shmid, IPC_RMID, 0)
+            print("Removed shmid %i" % self.shmid)
             self.shmid = None
 
     def __del__(self):
@@ -124,8 +125,9 @@ def next_power_of_two(n):
 
 class SharedNumpyArray:
     # cls members
-    server_instances = set()
-    extra_space = 4048
+    ServerInstances = set()
+    MaxServerInstances = 2
+    ExtraSpaceBytes = 4048
     # local members
     is_server = False
     mem = None
@@ -135,7 +137,7 @@ class SharedNumpyArray:
     @classmethod
     def needed_mem_size(cls, shape, typestr):
         itemsize = int(typestr[2:])
-        mem_size = cls.extra_space + itemsize * numpy.prod(shape)
+        mem_size = cls.ExtraSpaceBytes + itemsize * numpy.prod(shape)
         return mem_size
 
     @classmethod
@@ -153,10 +155,11 @@ def create_copy(cls, array):
     @classmethod
     def create_new(cls, shape, strides, typestr):
         needed_mem_size = cls.needed_mem_size(shape=shape, typestr=typestr)
-        for inst in cls.server_instances:
+        for inst in cls.ServerInstances:
             assert isinstance(inst, SharedNumpyArray)
             if inst.is_in_use(): continue
-            if inst.mem.size < needed_mem_size: continue
+            if inst.mem.size < needed_mem_size:
+                inst._init_mem(shape=shape, typestr=typestr)
             inst._set_is_used(1)
             inst._create_numpy(shape=shape, strides=strides, typestr=typestr)
             return inst
@@ -168,11 +171,11 @@ def create_from_shared(cls, shape, strides, typestr, mem):
 
     def __init__(self, shape, strides, typestr, mem=None):
         if not mem:
+            assert len(self.ServerInstances) < self.MaxServerInstances
             self.is_server = True
-            mem_size = next_power_of_two(self.needed_mem_size(shape=shape, typestr=typestr))
-            self.mem = SharedMem(size=mem_size)
+            self._init_mem(shape=shape, typestr=typestr)
             self._set_is_used(1)
-            self.server_instances.add(self)
+            self.ServerInstances.add(self)
         else:
             self.is_server = False
             mem_size = self.needed_mem_size(shape=shape, typestr=typestr)
@@ -183,6 +186,14 @@ def __init__(self, shape, strides, typestr, mem=None):
             self.mem = mem
         self._create_numpy(shape=shape, strides=strides, typestr=typestr)
 
+    def _init_mem(self, shape, typestr):
+        assert self.is_server
+        if self.mem:
+            self.mem.remove()
+            self.mem = None
+        mem_size = next_power_of_two(self.needed_mem_size(shape=shape, typestr=typestr))
+        self.mem = SharedMem(size=mem_size)
+
     def _create_numpy(self, shape, strides, typestr):
         assert self.mem.ptr > 0
         self.shape = shape
@@ -190,7 +201,7 @@ def _create_numpy(self, shape, strides, typestr):
         self.typestr = typestr
         # http://docs.scipy.org/doc/numpy/reference/arrays.interface.html
         array_intf = {
-            "data": (self.mem.ptr + self.extra_space, False),
+            "data": (self.mem.ptr + self.ExtraSpaceBytes, False),
             "shape": shape,
             "strides": strides,
             'typestr': typestr,
@@ -296,6 +307,8 @@ def demo():
         assert isinstance(m2, numpy.ndarray)
         assert m.shape == m2.shape
         assert numpy.isclose(m, m2).all()
+        del m2
+        gc.collect()
     print("Copying done, exiting.")
     pickle(p.stdin, ("exit",))
     out, = unpickle(p.stdout)
@@ -316,11 +329,12 @@ def demo_client():
             pickle(out_stream, ("exit",))
             break
         elif cmd[0] == "ping":
-            a = cmd[1]
-            assert isinstance(a, numpy.ndarray)
-            pickle(out_stream, ("pong", a))
+            assert isinstance(cmd[1], numpy.ndarray)
+            pickle(out_stream, ("pong", cmd[1]))
         else:
             assert False, "unknown: %r" % cmd
+        del cmd
+        gc.collect()
     print("Exit from client!")