Example of neo/debug.py script starting a debugger on RTMIN+2 signal

neo/debug.py

+"""Example of script starting a debugger on RTMIN+2 signal
+
+The pdb is launched in a separate thread in order not to trigger timeouts.
+The prompt is accessible through network in case that the process is daemonized:
+  $ socat READLINE TCP:127.0.0.1:54930
+  > neo/debug.py(63)pdb()
+  -> app # this is Application instance
+  (Pdb) app
+  <neo.master.app.Application object at 0x1fc9750>
+"""
+
+if 1:
+    import socket, sys, threading
+    #from neo.lib.debug import getPdb
+    from pdb import Pdb as getPdb
+
+    class Socket(object):
+
+        def __init__(self, socket):
+            self._socket = socket
+            self._buf = ''
+
+        def write(self, data):
+            self._socket.send(data)
+
+        def readline(self):
+            recv = self._socket.recv
+            data = self._buf
+            while True:
+                i = 1 + data.find('\n')
+                if i:
+                    self._buf = data[i:]
+                    return data[:i]
+                d = recv(4096)
+                data += d
+                if not d:
+                    self._buf = ''
+                    return data
+
+        def flush(self):
+            pass
+
+        def closed(self):
+            self._socket.setblocking(0)
+            try:
+                self._socket.recv(0)
+                return True
+            except socket.error, (err, _):
+                if err != errno.EAGAIN:
+                    raise
+                self._socket.setblocking(1)
+            return False
+
+    def pdb(app):
+        s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
+        try:
+            s.bind(('127.0.0.1', 0))
+            s.listen(0)
+            print 'Listening to %u' % s.getsockname()[1]
+            _socket = Socket(s.accept()[0])
+        finally:
+            s.close()
+        getPdb(stdin=_socket, stdout=_socket).set_trace()
+        app # this is Application instance
+
+    f = sys._getframe(3)
+    try:
+        while f.f_code.co_name != 'run' or \
+              f.f_locals.get('self').__class__.__name__ != 'Application':
+            f = f.f_back
+        threading.Thread(target=pdb, args=(f.f_locals['self'],)).start()
+    finally:
+        del f