multiprocessing: Add AsyncResult.ready() with real async implementation.

multiprocessing/multiprocessing.py

@@ -1,5 +1,6 @@
 import os
 import pickle
+import select
 
 
 class Process:
@@ -67,12 +68,22 @@ class AsyncResult:
     def __init__(self, p, r):
         self.p = p
         self.r = r
+        self.ep = None
 
     def get(self):
         res = self.r.recv()
         self.p.join()
         return res
 
+    def ready(self):
+        if not self.ep:
+            self.ep = select.epoll()
+            self.ep.register(self.r.f.fileno(), select.EPOLLIN, None)
+        res = self.ep.poll(0)
+        if res:
+            self.ep.close()
+        return bool(res)
+
 
 class Pool:
 

multiprocessing/test_pool_async.py

@@ -1,3 +1,4 @@
+import time
 from multiprocessing import Pool
 
 def f(x):
@@ -6,3 +7,14 @@ def f(x):
 pool = Pool(4)
 future = pool.apply_async(f, (10,))
 print(future.get())
+
+def f2(x):
+    time.sleep(1)
+    return x + 1
+
+future = pool.apply_async(f2, (10,))
+while not future.ready():
+    print("not ready")
+    time.sleep(0.1)
+
+print(future.get())