diff --git a/llama-index-core/llama_index/core/agent/legacy/react/base.py b/llama-index-core/llama_index/core/agent/legacy/react/base.py
index cfc512c23d83ab3b6dc0f0612279deb9455a3a85..36565a849756a9fc5d109a6277b8c0637c362e14 100644
--- a/llama-index-core/llama_index/core/agent/legacy/react/base.py
+++ b/llama-index-core/llama_index/core/agent/legacy/react/base.py
@@ -518,10 +518,10 @@ class ReActAgent(BaseAgent):
achat_stream=response_stream, sources=self.sources
)
# create task to write chat response to history
- asyncio.create_task(
+ chat_stream_response.awrite_response_to_history_task = asyncio.create_task(
chat_stream_response.awrite_response_to_history(self._memory)
)
- # thread.start()
+
return chat_stream_response
def get_tools(self, message: str) -> List[AsyncBaseTool]:
diff --git a/llama-index-core/llama_index/core/agent/react/step.py b/llama-index-core/llama_index/core/agent/react/step.py
index b7c8f6dd106d11a6fe9cf407879bd422d40e772d..e61e79e6c6ab88f5c9c3fb67f81f751395066d43 100644
--- a/llama-index-core/llama_index/core/agent/react/step.py
+++ b/llama-index-core/llama_index/core/agent/react/step.py
@@ -797,7 +797,7 @@ class ReActAgentWorker(BaseAgentWorker):
sources=task.extra_state["sources"],
)
# create task to write chat response to history
- asyncio.create_task(
+ agent_response_stream.awrite_response_to_history_task = asyncio.create_task(
agent_response_stream.awrite_response_to_history(
task.extra_state["new_memory"],
on_stream_end_fn=partial(self.finalize_task, task),
diff --git a/llama-index-core/llama_index/core/chat_engine/condense_question.py b/llama-index-core/llama_index/core/chat_engine/condense_question.py
index bb1c2717cbaa038c894ca6fd478598f464d03749..44d84b98793d733867f49d963d52b93eeb574a74 100644
--- a/llama-index-core/llama_index/core/chat_engine/condense_question.py
+++ b/llama-index-core/llama_index/core/chat_engine/condense_question.py
@@ -359,7 +359,10 @@ class CondenseQuestionChatEngine(BaseChatEngine):
),
sources=[tool_output],
)
- asyncio.create_task(response.awrite_response_to_history(self._memory))
+ response.awrite_response_to_history_task = asyncio.create_task(
+ response.awrite_response_to_history(self._memory)
+ )
+
else:
raise ValueError("Streaming is not enabled. Please use achat() instead.")
return response
diff --git a/llama-index-core/llama_index/core/chat_engine/simple.py b/llama-index-core/llama_index/core/chat_engine/simple.py
index c96b000b3288833037eaece84dab7b517f56345c..04b62bdfce9b36942ccf896077b80bd9f8257e85 100644
--- a/llama-index-core/llama_index/core/chat_engine/simple.py
+++ b/llama-index-core/llama_index/core/chat_engine/simple.py
@@ -202,7 +202,9 @@ class SimpleChatEngine(BaseChatEngine):
chat_response = StreamingAgentChatResponse(
achat_stream=await self._llm.astream_chat(all_messages)
)
- asyncio.create_task(chat_response.awrite_response_to_history(self._memory))
+ chat_response.awrite_response_to_history_task = asyncio.create_task(
+ chat_response.awrite_response_to_history(self._memory)
+ )
return chat_response
diff --git a/llama-index-core/llama_index/core/chat_engine/types.py b/llama-index-core/llama_index/core/chat_engine/types.py
index a100a697ee08ca760df86c07e17453963b7b74a8..79a0dcfad46b91ff7a30171beebe3078656eeeb3 100644
--- a/llama-index-core/llama_index/core/chat_engine/types.py
+++ b/llama-index-core/llama_index/core/chat_engine/types.py
@@ -124,6 +124,7 @@ class StreamingAgentChatResponse:
is_writing_to_memory: bool = True
# Track if an exception occurred
exception: Optional[Exception] = None
+ awrite_response_to_history_task: Optional[asyncio.Task] = None
def set_source_nodes(self) -> None:
if self.sources and not self.source_nodes:
@@ -300,34 +301,44 @@ class StreamingAgentChatResponse:
self.response = self.unformatted_response.strip()
async def async_response_gen(self) -> AsyncGenerator[str, None]:
- self._ensure_async_setup()
- assert self.aqueue is not None
-
- if self.is_writing_to_memory:
- while True:
- if not self.aqueue.empty() or not self.is_done:
- if self.exception is not None:
- raise self.exception
-
- try:
- delta = await asyncio.wait_for(self.aqueue.get(), timeout=0.1)
- except asyncio.TimeoutError:
- if self.is_done:
- break
- continue
- if delta is not None:
- self.unformatted_response += delta
- yield delta
- else:
- break
- else:
- if self.achat_stream is None:
- raise ValueError("achat_stream is None!")
+ try:
+ self._ensure_async_setup()
+ assert self.aqueue is not None
+
+ if self.is_writing_to_memory:
+ while True:
+ if not self.aqueue.empty() or not self.is_done:
+ if self.exception is not None:
+ raise self.exception
+
+ try:
+ delta = await asyncio.wait_for(
+ self.aqueue.get(), timeout=0.1
+ )
+ except asyncio.TimeoutError:
+ if self.is_done:
+ break
+ continue
+ if delta is not None:
+ self.unformatted_response += delta
+ yield delta
+ else:
+ break
+ else:
+ if self.achat_stream is None:
+ raise ValueError("achat_stream is None!")
- async for chat_response in self.achat_stream:
- self.unformatted_response += chat_response.delta or ""
- yield chat_response.delta or ""
- self.response = self.unformatted_response.strip()
+ async for chat_response in self.achat_stream:
+ self.unformatted_response += chat_response.delta or ""
+ yield chat_response.delta or ""
+ self.response = self.unformatted_response.strip()
+ finally:
+ if self.awrite_response_to_history_task:
+ # Make sure that the background task ran to completion, retrieve any exceptions
+ await self.awrite_response_to_history_task
+ self.awrite_response_to_history_task = (
+ None # No need to keep the reference to the finished task
+ )
def print_response_stream(self) -> None:
for token in self.response_gen:
diff --git a/llama-index-core/tests/chat_engine/test_simple.py b/llama-index-core/tests/chat_engine/test_simple.py
index 20dd816a52591e75190f276ccceb48ab37a48ea2..a307196492fd1124698502792f1b4c505e44ab58 100644
--- a/llama-index-core/tests/chat_engine/test_simple.py
+++ b/llama-index-core/tests/chat_engine/test_simple.py
@@ -1,3 +1,15 @@
+import gc
+import asyncio
+from llama_index.core.memory import ChatMemoryBuffer
+from llama_index.core.base.llms.types import (
+ ChatMessage,
+ CompletionResponse,
+ CompletionResponseGen,
+)
+from typing import Any
+from llama_index.core.llms.callbacks import llm_completion_callback
+from llama_index.core.llms.mock import MockLLM
+import pytest
from llama_index.core.base.llms.types import ChatMessage, MessageRole
from llama_index.core.chat_engine.simple import SimpleChatEngine
@@ -34,3 +46,86 @@ def test_simple_chat_engine_with_init_history() -> None:
str(response) == "user: test human message\nassistant: test ai message\n"
"user: new human message\nassistant: "
)
+
+
+@pytest.mark.asyncio()
+async def test_simple_chat_engine_astream():
+ engine = SimpleChatEngine.from_defaults()
+ response = await engine.astream_chat("Hello World!")
+
+ num_iters = 0
+ async for response_part in response.async_response_gen():
+ num_iters += 1
+
+ assert num_iters > 10
+
+ assert "Hello World!" in response.unformatted_response
+ assert len(engine.chat_history) == 2
+
+ response = await engine.astream_chat("What is the capital of the moon?")
+
+ num_iters = 0
+ async for _ in response.async_response_gen():
+ num_iters += 1
+
+ assert num_iters > 10
+ assert "Hello World!" in response.unformatted_response
+ assert "What is the capital of the moon?" in response.unformatted_response
+
+
+def test_simple_chat_engine_astream_exception_handling():
+ """Test that an exception thrown while retrieving the streamed LLM response gets bubbled up to the user.
+ Also tests that the non-retrieved exception does not remain in an task that was not awaited leading to
+ a 'Task exception was never retrieved' message during garbage collection.
+ """
+
+ class ExceptionThrownInTest(Exception):
+ pass
+
+ class ExceptionMockLLM(MockLLM):
+ """Raises an exception while streaming back the mocked LLM response."""
+
+ @classmethod
+ def class_name(cls) -> str:
+ return "ExceptionMockLLM"
+
+ @llm_completion_callback()
+ def stream_complete(
+ self, prompt: str, formatted: bool = False, **kwargs: Any
+ ) -> CompletionResponseGen:
+ def gen_prompt() -> CompletionResponseGen:
+ for ch in prompt:
+ yield CompletionResponse(
+ text=prompt,
+ delta=ch,
+ )
+ raise ExceptionThrownInTest("Exception thrown for testing purposes")
+
+ return gen_prompt()
+
+ async def async_part():
+ engine = SimpleChatEngine.from_defaults(
+ llm=ExceptionMockLLM(), memory=ChatMemoryBuffer.from_defaults()
+ )
+ response = await engine.astream_chat("Hello World!")
+
+ with pytest.raises(ExceptionThrownInTest):
+ async for response_part in response.async_response_gen():
+ pass
+
+ not_retrieved_exception = False
+
+ def custom_exception_handler(loop, context):
+ if context.get("message") == "Task exception was never retrieved":
+ nonlocal not_retrieved_exception
+ not_retrieved_exception = True
+
+ loop = asyncio.new_event_loop()
+ loop.set_exception_handler(custom_exception_handler)
+ result = loop.run_until_complete(async_part())
+ loop.close()
+ gc.collect()
+ if not_retrieved_exception:
+ pytest.fail(
+ "Exception was not correctly handled - ended up in asyncio cleanup performed during garbage collection"
+ )
diff --git a/llama-index-integrations/agent/llama-index-agent-openai-legacy/llama_index/agent/openai_legacy/openai_agent.py b/llama-index-integrations/agent/llama-index-agent-openai-legacy/llama_index/agent/openai_legacy/openai_agent.py
index ebb022f21931ac3ce9bc7d34d3ff749542a529bc..64198deffd00047a905eafbc4d068eeee24411ce 100644
--- a/llama-index-integrations/agent/llama-index-agent-openai-legacy/llama_index/agent/openai_legacy/openai_agent.py
+++ b/llama-index-integrations/agent/llama-index-agent-openai-legacy/llama_index/agent/openai_legacy/openai_agent.py
@@ -244,7 +244,7 @@ class BaseOpenAIAgent(BaseAgent):
sources=self.sources,
)
# create task to write chat response to history
- asyncio.create_task(
+ chat_stream_response.awrite_response_to_history_task = asyncio.create_task(
chat_stream_response.awrite_response_to_history(self.memory)
)
# wait until openAI functions stop executing
diff --git a/llama-index-integrations/agent/llama-index-agent-openai/llama_index/agent/openai/step.py b/llama-index-integrations/agent/llama-index-agent-openai/llama_index/agent/openai/step.py
index 0d00c1dc0eb96fe8755e0f68c683f13211b01b6c..2324b6b0f10b15dbe664923c9d632d191c701adf 100644
--- a/llama-index-integrations/agent/llama-index-agent-openai/llama_index/agent/openai/step.py
+++ b/llama-index-integrations/agent/llama-index-agent-openai/llama_index/agent/openai/step.py
@@ -277,7 +277,7 @@ class OpenAIAgentWorker(BaseAgentWorker):
sources=task.extra_state["sources"],
)
# create task to write chat response to history
- asyncio.create_task(
+ chat_stream_response.awrite_response_to_history_task = asyncio.create_task(
chat_stream_response.awrite_response_to_history(
task.extra_state["new_memory"],
on_stream_end_fn=partial(self.afinalize_task, task),