Have the squashing system write the data (via a double queue system and multiprocessing) to both the client and the stack's storage. On subsequent calls, if the synthetic image exists, it will be returned directly instead of being recomputed

util/queuefile.py

@@ -0,0 +1,37 @@
+from multiprocessing import Queue
+import os
+
+class QueueFile(object):
+  """ Class which implements a file-like interface and reads from a blocking
+      multiprocessing queue.
+  """
+  def __init__(self, queue, name=None):
+    self._queue = queue
+    self._closed = False
+    self._done = False
+    self._buffer = ''
+    self._total_size = 0
+    self._name = name
+
+  def read(self, size=8192):
+    if self._closed or self._done:
+      return None
+
+    while len(self._buffer) < size:
+      result = self._queue.get(block=True)
+      if result is None:
+        self._done = True
+        break
+      
+      self._buffer += result
+      self._total_size += len(result)
+    
+    buf = self._buffer[0:size]
+    self._buffer = self._buffer[size:]
+    return buf
+
+  def flush(self):
+    pass
+
+  def close(self):
+    self._closed = True