From f7e288fa2599a93d33e605cb044b71cb0eecd27f Mon Sep 17 00:00:00 2001
From: David Wilson <dw@botanicus.net>
Date: Thu, 19 Jul 2018 15:12:54 -0400
Subject: [PATCH] core: fd 0/1 were accidently made non-blocking.

This breaks regular code. Triggered by a huge pprint() in the child to
stdout.
---
 mitogen/core.py | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/mitogen/core.py b/mitogen/core.py
index 6f536ec8..c0b864f7 100644
--- a/mitogen/core.py
+++ b/mitogen/core.py
@@ -851,7 +851,7 @@ class LogHandler(logging.Handler):
 class Side(object):
     _fork_refs = weakref.WeakValueDictionary()
 
-    def __init__(self, stream, fd, cloexec=True, keep_alive=True):
+    def __init__(self, stream, fd, cloexec=True, keep_alive=True, blocking=False):
         self.stream = stream
         self.fd = fd
         self.closed = False
@@ -859,7 +859,8 @@ class Side(object):
         self._fork_refs[id(self)] = self
         if cloexec:
             set_cloexec(fd)
-        set_nonblock(fd)
+        if not blocking:
+            set_nonblock(fd)
 
     def __repr__(self):
         return '<Side of %r fd %s>' % (self.stream, self.fd)
@@ -1520,7 +1521,7 @@ class IoLogger(BasicStream):
         set_cloexec(self._wsock.fileno())
 
         self.receive_side = Side(self, self._rsock.fileno())
-        self.transmit_side = Side(self, dest_fd, cloexec=False)
+        self.transmit_side = Side(self, dest_fd, cloexec=False, blocking=True)
         self._broker.start_receive(self)
 
     def __repr__(self):