enable_attach() no longer hangs if called from top level of an imported module on Python 2.7. Fixes #1788

src/ptvsd/_vendored/pydevd/_pydevd_bundle/pydevd_comm.py

@@ -115,6 +115,9 @@ except:
 # CMD_XXX constants imported for backward compatibility
 from _pydevd_bundle.pydevd_comm_constants import *  # @UnusedWildImport
 
+if IS_WINDOWS:
+    from socket import SO_EXCLUSIVEADDRUSE
+
 if IS_JYTHON:
     import org.python.core as JyCore  # @UnresolvedImport
 
@@ -187,10 +190,8 @@ def run_as_pydevd_daemon_thread(func, *args, **kwargs):
 class ReaderThread(PyDBDaemonThread):
     ''' reader thread reads and dispatches commands in an infinite loop '''
 
-    def __init__(self, sock, py_db, terminate_on_socket_close=True):
+    def __init__(self, sock, py_db, PyDevJsonCommandProcessor, process_net_command, terminate_on_socket_close=True):
         assert sock is not None
-        from _pydevd_bundle.pydevd_process_net_command_json import PyDevJsonCommandProcessor
-        from _pydevd_bundle.pydevd_process_net_command import process_net_command
         PyDBDaemonThread.__init__(self)
         self._terminate_on_socket_close = terminate_on_socket_close
 
@@ -429,7 +430,6 @@ def create_server_socket(host, port):
     try:
         server = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP)
         if IS_WINDOWS:
-            from socket import SO_EXCLUSIVEADDRUSE
             server.setsockopt(SOL_SOCKET, SO_EXCLUSIVEADDRUSE, 1)
         else:
             server.setsockopt(SOL_SOCKET, SO_REUSEADDR, 1)

src/ptvsd/_vendored/pydevd/_pydevd_bundle/pydevd_constants.py

@@ -18,6 +18,11 @@ except NameError:
 
 import sys  # Note: the sys import must be here anyways (others depend on it)
 
+# Preload codecs to avoid imports to them later on which can potentially halt the debugger.
+import codecs as _codecs
+for _codec in ["ascii", "utf8", "utf-8", "latin1", "latin-1", "idna"]:
+    _codecs.lookup(_codec)
+
 
 class DebugInfoHolder:
     # we have to put it here because it can be set through the command line (so, the

src/ptvsd/_vendored/pydevd/pydevd.py

@@ -67,6 +67,9 @@ from _pydevd_bundle.pydevd_comm import(InternalConsoleExec,
     start_client, start_server, InternalGetBreakpointException, InternalSendCurrExceptionTrace,
     InternalSendCurrExceptionTraceProceeded, run_as_pydevd_daemon_thread)
 
+from _pydevd_bundle.pydevd_process_net_command_json import PyDevJsonCommandProcessor
+from _pydevd_bundle.pydevd_process_net_command import process_net_command
+
 from _pydevd_bundle.pydevd_breakpoints import stop_on_unhandled_exception
 from _pydevd_bundle.pydevd_collect_try_except_info import collect_try_except_info
 from _pydevd_bundle.pydevd_suspended_frames import SuspendedFramesManager
@@ -1127,7 +1130,13 @@ class PyDB(object):
             curr_writer.do_kill_pydev_thread()
 
         self.writer = WriterThread(sock, self, terminate_on_socket_close=terminate_on_socket_close)
-        self.reader = ReaderThread(sock, self, terminate_on_socket_close=terminate_on_socket_close)
+        self.reader = ReaderThread(
+            sock,
+            self,
+            PyDevJsonCommandProcessor=PyDevJsonCommandProcessor,
+            process_net_command=process_net_command,
+            terminate_on_socket_close=terminate_on_socket_close
+        )
         self.writer.start()
         self.reader.start()
 
@@ -2568,7 +2577,13 @@ class DispatchReader(ReaderThread):
 
     def __init__(self, dispatcher):
         self.dispatcher = dispatcher
-        ReaderThread.__init__(self, self.dispatcher.client)
+
+        ReaderThread.__init__(
+            self,
+            self.dispatcher.client,
+            PyDevJsonCommandProcessor=PyDevJsonCommandProcessor,
+            process_net_command=process_net_command,
+        )
 
     @overrides(ReaderThread._on_run)
     def _on_run(self):

src/ptvsd/_vendored/pydevd/tests_python/resources/_debugger_case_wait_for_attach.py

@@ -1,50 +1,3 @@
 if __name__ == '__main__':
-    import os
-    import sys
-    import time
-    port = int(sys.argv[1])
-    root_dirname = os.path.dirname(os.path.dirname(__file__))
-
-    if root_dirname not in sys.path:
-        sys.path.append(root_dirname)
-
-    import pydevd
-    try:
-        pydevd._wait_for_attach()  # Cannot be called before _enable_attach.
-    except AssertionError:
-        pass
-    else:
-        raise AssertionError('Expected _wait_for_attach to raise exception.')
-
-    assert sys.gettrace() is None
-    print('enable attach to port: %s' % (port,))
-    pydevd._enable_attach(('127.0.0.1', port))
-    pydevd._enable_attach(('127.0.0.1', port))  # no-op in practice
-
-    try:
-        pydevd._enable_attach(('127.0.0.1', port + 15))  # different port: raise error.
-    except AssertionError:
-        pass
-    else:
-        raise AssertionError('Expected _enable_attach to raise exception (because it is already hearing in another port).')
-
-    assert pydevd.get_global_debugger() is not None
-    assert sys.gettrace() is not None
-
-    a = 10  # Break 1
-    print('wait for attach')
-    pydevd._wait_for_attach()
-    print('finished wait for attach')
-    pydevd._wait_for_attach()  # Should promptly return (already connected).
-
-    a = 20  # Break 2
-
-    pydevd._wait_for_attach()  # As we disconnected on the 2nd break, this one should wait until a new configurationDone.
-
-    a = 20  # Break 3
-
-    while a == 20:  # Pause 1
-        # The debugger should disconnect/reconnect, pause and then change 'a' to another value.
-        time.sleep(1 / 20.)  # Pause 2
-
-    print('TEST SUCEEDED!')
+    # We want to call _enable_attach inside an import to make sure that it works properly that way.
+    import _debugger_case_wait_for_attach_impl

src/ptvsd/_vendored/pydevd/tests_python/resources/_debugger_case_wait_for_attach_impl.py

@@ -0,0 +1,49 @@
+import os
+import sys
+import time
+port = int(sys.argv[1])
+root_dirname = os.path.dirname(os.path.dirname(__file__))
+
+if root_dirname not in sys.path:
+    sys.path.append(root_dirname)
+
+import pydevd
+try:
+    pydevd._wait_for_attach()  # Cannot be called before _enable_attach.
+except AssertionError:
+    pass
+else:
+    raise AssertionError('Expected _wait_for_attach to raise exception.')
+
+assert sys.gettrace() is None
+print('enable attach to port: %s' % (port,))
+pydevd._enable_attach(('127.0.0.1', port))
+pydevd._enable_attach(('127.0.0.1', port))  # no-op in practice
+
+try:
+    pydevd._enable_attach(('127.0.0.1', port + 15))  # different port: raise error.
+except AssertionError:
+    pass
+else:
+    raise AssertionError('Expected _enable_attach to raise exception (because it is already hearing in another port).')
+
+assert pydevd.get_global_debugger() is not None
+assert sys.gettrace() is not None
+
+a = 10  # Break 1
+print('wait for attach')
+pydevd._wait_for_attach()
+print('finished wait for attach')
+pydevd._wait_for_attach()  # Should promptly return (already connected).
+
+a = 20  # Break 2
+
+pydevd._wait_for_attach()  # As we disconnected on the 2nd break, this one should wait until a new configurationDone.
+
+a = 20  # Break 3
+
+while a == 20:  # Pause 1
+    # The debugger should disconnect/reconnect, pause and then change 'a' to another value.
+    time.sleep(1 / 20.)  # Pause 2
+
+print('TEST SUCEEDED!')

src/ptvsd/_vendored/pydevd/tests_python/test_debugger_json.py

@@ -2426,6 +2426,7 @@ def test_wait_for_attach(case_setup_remote_attach_to):
         assert next(iter(process_events)).body.startMethod == start_method
 
     with case_setup_remote_attach_to.test_file('_debugger_case_wait_for_attach.py', host_port[1]) as writer:
+        writer.TEST_FILE = debugger_unittest._get_debugger_test_file('_debugger_case_wait_for_attach_impl.py')
         time.sleep(.5)  # Give some time for it to pass the first breakpoint and wait in 'wait_for_attach'.
         writer.start_socket_client(*host_port)