From e21480855fd66fdb9161c8b77e49340a3713a9ba Mon Sep 17 00:00:00 2001
From: Luke Campagnola <>
Date: Fri, 17 Aug 2012 16:15:13 -0400
Subject: [PATCH] multiprocess updates:   - avoid sending keyboard interrupt
 signals to child processes   - parallelizer keeps better track of processes
 that die unexpectedly   - added ability to specify a different executable
 when starting new processes

---
 multiprocess/bootstrap.py    |  3 ++-
 multiprocess/parallelizer.py | 15 ++++++++++++---
 multiprocess/processes.py    |  9 ++++++---
 multiprocess/remoteproxy.py  | 11 ++++++++++-
 4 files changed, 30 insertions(+), 8 deletions(-)

diff --git a/multiprocess/bootstrap.py b/multiprocess/bootstrap.py
index 196d34c8..e0d1c02c 100644
--- a/multiprocess/bootstrap.py
+++ b/multiprocess/bootstrap.py
@@ -1,7 +1,8 @@
 """For starting up remote processes"""
-import sys, pickle
+import sys, pickle, os
 
 if __name__ == '__main__':
+    os.setpgrp()  ## prevents signals (notably keyboard interrupt) being forwarded from parent to this process
     name, port, authkey, targetStr, path = pickle.load(sys.stdin)
     if path is not None:
         ## rewrite sys.path without assigning a new object--no idea who already has a reference to the existing list.
diff --git a/multiprocess/parallelizer.py b/multiprocess/parallelizer.py
index eda82d31..6447efae 100644
--- a/multiprocess/parallelizer.py
+++ b/multiprocess/parallelizer.py
@@ -85,12 +85,14 @@ class Parallelize:
     def __exit__(self, *exc_info):
         
         if self.proc is not None:  ## worker 
+            exceptOccurred = exc_info[0] is not None ## hit an exception during processing.
+                
             try:
-                if exc_info[0] is not None:
+                if exceptOccurred:
                     sys.excepthook(*exc_info)
             finally:
                 #print os.getpid(), 'exit'
-                os._exit(0)
+                os._exit(1 if exceptOccurred else 0)
                 
         else:  ## parent
             if self.showProgress:
@@ -137,6 +139,7 @@ class Parallelize:
             ## process events from workers until all have exited.
                 
             activeChilds = self.childs[:]
+            self.exitCodes = []
             pollInterval = 0.01
             while len(activeChilds) > 0:
                 waitingChildren = 0
@@ -156,7 +159,8 @@ class Parallelize:
                     activeChilds.remove(ch)
                     while True:
                         try:
-                            os.waitpid(ch.childPid, 0)
+                            pid, exitcode = os.waitpid(ch.childPid, 0)
+                            self.exitCodes.append(exitcode)
                             break
                         except OSError as ex:
                             if ex.errno == 4:  ## If we get this error, just try again
@@ -183,6 +187,11 @@ class Parallelize:
         finally:
             if self.showProgress:
                 self.progressDlg.__exit__(None, None, None)
+        if len(self.exitCodes) < len(self.childs):
+            raise Exception("Parallelizer started %d processes but only received exit codes from %d." % (len(self.childs), len(self.exitCodes)))
+        for code in self.exitCodes:
+            if code != 0:
+                raise Exception("Error occurred in parallel-executed subprocess (console output may have more information).")
         return []  ## no tasks for parent process.
     
     
diff --git a/multiprocess/processes.py b/multiprocess/processes.py
index c14b8b0a..a4769679 100644
--- a/multiprocess/processes.py
+++ b/multiprocess/processes.py
@@ -31,7 +31,7 @@ class Process(RemoteEventHandler):
     ProxyObject for more information.
     """
     
-    def __init__(self, name=None, target=None, copySysPath=True):
+    def __init__(self, name=None, target=None, executable=None, copySysPath=True):
         """
         ============  =============================================================
         Arguments:
@@ -50,6 +50,8 @@ class Process(RemoteEventHandler):
             target = startEventLoop
         if name is None:
             name = str(self)
+        if executable is None:
+            executable = sys.executable
         
         ## random authentication key
         authkey = ''.join([chr(random.getrandbits(7)) for i in range(20)])
@@ -68,7 +70,7 @@ class Process(RemoteEventHandler):
         ## start remote process, instruct it to run target function
         sysPath = sys.path if copySysPath else None
         bootstrap = os.path.abspath(os.path.join(os.path.dirname(__file__), 'bootstrap.py'))
-        self.proc = subprocess.Popen((sys.executable, bootstrap), stdin=subprocess.PIPE)
+        self.proc = subprocess.Popen((executable, bootstrap), stdin=subprocess.PIPE)
         targetStr = pickle.dumps(target)  ## double-pickle target so that child has a chance to 
                                           ## set its sys.path properly before unpickling the target
         pickle.dump((name+'_child', port, authkey, targetStr, sysPath), self.proc.stdin)
@@ -166,7 +168,8 @@ class ForkedProcess(RemoteEventHandler):
             ##   - no reading/writing file handles/sockets owned by parent process (stdout is ok)
             ##   - don't touch QtGui or QApplication at all; these are landmines.
             ##   - don't let the process call exit handlers
-            ##   -  
+            
+            os.setpgrp()  ## prevents signals (notably keyboard interrupt) being forwarded from parent to this process
             
             ## close all file handles we do not want shared with parent
             conn.close()
diff --git a/multiprocess/remoteproxy.py b/multiprocess/remoteproxy.py
index c15c5b9d..4f13b5c6 100644
--- a/multiprocess/remoteproxy.py
+++ b/multiprocess/remoteproxy.py
@@ -60,7 +60,11 @@ class RemoteEventHandler(object):
     
     @classmethod
     def getHandler(cls, pid):
-        return cls.handlers[pid]
+        try:
+            return cls.handlers[pid]
+        except:
+            print pid, cls.handlers
+            raise
     
     def getProxyOption(self, opt):
         return self.proxyOptions[opt]
@@ -88,6 +92,11 @@ class RemoteEventHandler(object):
             except ExitError:
                 self.exited = True
                 raise
+            except IOError as err:
+                if err.errno == 4:  ## interrupted system call; try again
+                    continue
+                else:
+                    raise
             except:
                 print "Error in process %s" % self.name
                 sys.excepthook(*sys.exc_info())