Fix race in daemon initialize using delegate_to

Ensure only one thread can start up an accelerate daemon on a target
host where multiple hosts may be specified in the play, gather facts is
disabled and the first task delegates to the same target host.

This will slow down the initial connection to only allowing a single
thread setup a connection at a time, however this should be of a
negligible impact overall.

1 files changed, 13 insertions, 1 deletions

diff --git a/lib/ansible/runner/connection_plugins/accelerate.py b/lib/ansible/runner/connection_plugins/accelerate.py
index 0627267c16..8b3d961854 100644
--- a/lib/ansible/runner/connection_plugins/accelerate.py
+++ b/lib/ansible/runner/connection_plugins/accelerate.py
@@ -21,6 +21,7 @@ import base64
 import socket
 import struct
 import time
+import threading
 from ansible.callbacks import vvv, vvvv
 from ansible.errors import AnsibleError, AnsibleFileNotFound
 from ansible.runner.connection_plugins.ssh import Connection as SSHConnection
@@ -35,6 +36,8 @@ from ansible import constants
 # multiple of the value to speed up file reads.
 CHUNK_SIZE=1044*20
 
+_LOCK = threading.Lock()
+
 class Connection(object):
     ''' raw socket accelerated connection '''
 
@@ -111,6 +114,15 @@ class Connection(object):
     def connect(self, allow_ssh=True):
         ''' activates the connection object '''
 
+        # ensure only one fork tries to setup the connection, in case the
+        # first task for multiple hosts is delegated to the same host.
+        if not self.is_connected:
+            with(_LOCK):
+                return self._connect(allow_ssh)
+
+        return self
+
+    def _connect(self, allow_ssh=True):
         try:
             if not self.is_connected:
                 wrong_user = False
@@ -150,7 +162,7 @@ class Connection(object):
                 res = self._execute_accelerate_module()
                 if not res.is_successful():
                     raise AnsibleError("Failed to launch the accelerated daemon on %s (reason: %s)" % (self.host,res.result.get('msg')))
-                return self.connect(allow_ssh=False)
+                return self._connect(allow_ssh=False)
             else:
                 raise AnsibleError("Failed to connect to %s:%s" % (self.host,self.accport))
         self.is_connected = True