Change interprocess communication from synced dict to pipe

Author: rotu

colcon_core/package_identification/python.py

@@ -66,32 +66,33 @@ def get_setup_result(setup_py, env=None):
     :param env: environment variables to set before running setup.py
     :return: Dictionary of data describing the package.
     """
-    with multiprocessing.Manager() as manager:
-        d = manager.dict()
-        p = multiprocessing.Process(
-            target=_get_setup_result_target,
-            args=(setup_py, env, d)
-        )
-        p.start()
-        p.join()
-        if p.exitcode:
-            logger.warn("setup script %s terminated with exit code %d",
-                        setup_py, p.exitcode)
-
-        # turn the DictProxy into a dict
-        return dict(d)
-
-
-def _get_setup_result_target(setup_py, env, out_dict):
+
+    conn_recv, conn_send = multiprocessing.Pipe(duplex=False)
+    p = multiprocessing.Process(
+        target=_get_setup_result_target,
+        args=(setup_py, env, conn_send)
+    )
+    p.start()
+    p.join()
+    if p.exitcode:
+        logger.warn("Python setup script '%s' terminated with exit code %d",
+                    setup_py, p.exitcode)
+
+    if not conn_recv.poll():
+        return None
+    return conn_recv.recv()
+
+
+def _get_setup_result_target(setup_py, env, conn_send):
     """
     Run setup.py in a modified environment.
 
     Helper function for get_setup_metadata.
 
     :param setup_py: path to a setup.py script
     :param env: environment variables to set before running setup.py
-    :param out_dict: dict to populate with the results of setup.py
-    :return: None
+    :param conn_send: Connection to send the results dictionary
+    :return: None. Results are transmitted via conn_send.
     """
     import os
     import distutils.core
@@ -108,8 +109,8 @@ def _get_setup_result_target(setup_py, env, out_dict):
 
     # could just return all attrs in result.__dict__, but we take this
     # opportunity to filter a few things that don't need to be there
-    out_dict.update([
-        (attr, value) for attr, value in result.__dict__.items()
+    conn_send.send({
+        attr: value for attr, value in result.__dict__.items()
         if (
             # These *seem* useful but always have the value 0.
             # Look for their values in the 'metadata' object instead.
@@ -118,7 +119,7 @@ def _get_setup_result_target(setup_py, env, out_dict):
             and not callable(value)
             # Private properties
             and not attr.startswith('_')
-        )])
+        )})
 
 
 def create_dependency_descriptor(requirement_string):