Fix iostream on new thread (#2181)

* fixed get_stream in new thread by introducing a global default

* fixed get_stream in new thread by introducing a global default

---------

Co-authored-by: Chi Wang <wang.chi@microsoft.com>

autogen/io/__init__.py

@@ -3,6 +3,7 @@ from .console import IOConsole
 from .websockets import IOWebsockets
 
 # Set the default input/output stream to the console
-IOStream._default_io_stream.set(IOConsole())
+IOStream.set_global_default(IOConsole())
+IOStream.set_default(IOConsole())
 
 __all__ = ("IOConsole", "IOStream", "InputStream", "OutputStream", "IOWebsockets")

autogen/io/base.py

@@ -1,9 +1,12 @@
 from contextlib import contextmanager
 from contextvars import ContextVar
+import logging
 from typing import Any, Iterator, Optional, Protocol, runtime_checkable
 
 __all__ = ("OutputStream", "InputStream", "IOStream")
 
+logger = logging.getLogger(__name__)
+
 
 @runtime_checkable
 class OutputStream(Protocol):
@@ -39,6 +42,31 @@ class InputStream(Protocol):
 class IOStream(InputStream, OutputStream, Protocol):
     """A protocol for input/output streams."""
 
+    # ContextVar must be used in multithreaded or async environments
+    _default_io_stream: ContextVar[Optional["IOStream"]] = ContextVar("default_iostream", default=None)
+    _default_io_stream.set(None)
+    _global_default: Optional["IOStream"] = None
+
+    @staticmethod
+    def set_global_default(stream: "IOStream") -> None:
+        """Set the default input/output stream.
+
+        Args:
+            stream (IOStream): The input/output stream to set as the default.
+        """
+        IOStream._global_default = stream
+
+    @staticmethod
+    def get_global_default() -> "IOStream":
+        """Get the default input/output stream.
+
+        Returns:
+            IOStream: The default input/output stream.
+        """
+        if IOStream._global_default is None:
+            raise RuntimeError("No global default IOStream has been set")
+        return IOStream._global_default
+
     @staticmethod
     def get_default() -> "IOStream":
         """Get the default input/output stream.
@@ -48,13 +76,10 @@ class IOStream(InputStream, OutputStream, Protocol):
         """
         iostream = IOStream._default_io_stream.get()
         if iostream is None:
-            raise RuntimeError("No default IOStream has been set")
+            logger.warning("No default IOStream has been set, defaulting to IOConsole.")
+            return IOStream.get_global_default()
         return iostream
 
-    # ContextVar must be used in multithreaded or async environments
-    _default_io_stream: ContextVar[Optional["IOStream"]] = ContextVar("default_iostream")
-    _default_io_stream.set(None)
-
     @staticmethod
     @contextmanager
     def set_default(stream: Optional["IOStream"]) -> Iterator[None]:

test/io/test_base.py

@@ -1,4 +1,5 @@
-from typing import Any
+from threading import Thread
+from typing import Any, List
 
 from autogen.io import IOConsole, IOStream, IOWebsockets
 
@@ -26,3 +27,23 @@ class TestIOStream:
             assert isinstance(IOStream.get_default(), MyIOStream)
 
         assert isinstance(IOStream.get_default(), IOConsole)
+
+    def test_get_default_on_new_thread(self) -> None:
+        exceptions: List[Exception] = []
+
+        def on_new_thread(exceptions: List[Exception] = exceptions) -> None:
+            try:
+                assert isinstance(IOStream.get_default(), IOConsole)
+            except Exception as e:
+                exceptions.append(e)
+
+        # create a new thread and run the function
+        thread = Thread(target=on_new_thread)
+
+        thread.start()
+
+        # get exception from the thread
+        thread.join()
+
+        if exceptions:
+            raise exceptions[0]