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fix: hold references to the persistence tasks #3007

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fix: hold references to the persistence tasks #3007

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1637ed6
fix: hold references to the persistence tasks
noron12234 Jul 31, 2026
cbfcbd1
fix: hold references to the two remaining discarded step tasks
noron12234 Aug 4, 2026
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9 changes: 8 additions & 1 deletion backend/chainlit/context.py
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Original file line number Diff line number Diff line change
Expand Up @@ -7,6 +7,11 @@

from chainlit.session import ClientType, HTTPSession, WebsocketSession

# The event loop only keeps weak references to tasks, so a persistence task
# whose only reference was the create_task() call can be garbage collected
# before it reaches the data layer. Hold each one until it completes.
_persistence_tasks: set[asyncio.Task] = set()

if TYPE_CHECKING:
from chainlit.emitter import BaseChainlitEmitter
from chainlit.step import Step
Expand Down Expand Up @@ -95,9 +100,11 @@ def init_http_context(

if data_layer := get_data_layer():
if user_id := getattr(user, "id", None):
asyncio.create_task(
_task = asyncio.create_task(
data_layer.update_thread(thread_id=thread_id, user_id=user_id)
)
_persistence_tasks.add(_task)
_task.add_done_callback(_persistence_tasks.discard)

return context

Expand Down
9 changes: 8 additions & 1 deletion backend/chainlit/element.py
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Original file line number Diff line number Diff line change
Expand Up @@ -24,6 +24,11 @@
from chainlit.data import get_data_layer
from chainlit.logger import logger

# The event loop only keeps weak references to tasks, so a persistence task
# whose only reference was the create_task() call can be garbage collected
# before it reaches the data layer. Hold each one until it completes.
_persistence_tasks: set[asyncio.Task] = set()

mime_types = {
"text": "text/plain",
"tasklist": "application/json",
Expand Down Expand Up @@ -212,7 +217,9 @@ async def _create(self, persist=True) -> bool:

if (data_layer := get_data_layer()) and persist:
try:
asyncio.create_task(data_layer.create_element(self))
_task = asyncio.create_task(data_layer.create_element(self))
_persistence_tasks.add(_task)
_task.add_done_callback(_persistence_tasks.discard)
except Exception as e:
logger.error(f"Failed to create element: {e!s}")
if not self.url and (not self.chainlit_key or self.updatable):
Expand Down
17 changes: 14 additions & 3 deletions backend/chainlit/message.py
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Original file line number Diff line number Diff line change
Expand Up @@ -27,6 +27,11 @@
)
from chainlit.utils import utc_now

# The event loop only keeps weak references to tasks, so a persistence task
# whose only reference was the create_task() call can be garbage collected
# before it reaches the data layer. Hold each one until it completes.
_persistence_tasks: set[asyncio.Task] = set()


class MessageBase(ABC):
id: str
Expand Down Expand Up @@ -113,7 +118,9 @@ async def update(
data_layer = get_data_layer()
if data_layer:
try:
asyncio.create_task(data_layer.update_step(step_dict))
_task = asyncio.create_task(data_layer.update_step(step_dict))
_persistence_tasks.add(_task)
_task.add_done_callback(_persistence_tasks.discard)
except Exception as e:
if self.fail_on_persist_error:
raise e
Expand All @@ -132,7 +139,9 @@ async def remove(self):
data_layer = get_data_layer()
if data_layer:
try:
asyncio.create_task(data_layer.delete_step(step_dict["id"]))
_task = asyncio.create_task(data_layer.delete_step(step_dict["id"]))
_persistence_tasks.add(_task)
_task.add_done_callback(_persistence_tasks.discard)
except Exception as e:
if self.fail_on_persist_error:
raise e
Expand All @@ -147,7 +156,9 @@ async def _create(self):
data_layer = get_data_layer()
if data_layer and not self.persisted:
try:
asyncio.create_task(data_layer.create_step(step_dict))
_task = asyncio.create_task(data_layer.create_step(step_dict))
_persistence_tasks.add(_task)
_task.add_done_callback(_persistence_tasks.discard)
self.persisted = True
except Exception as e:
if self.fail_on_persist_error:
Expand Down
25 changes: 20 additions & 5 deletions backend/chainlit/step.py
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Original file line number Diff line number Diff line change
Expand Up @@ -18,6 +18,11 @@
from chainlit.types import FeedbackDict
from chainlit.utils import utc_now

# The event loop only keeps weak references to tasks, so a persistence task
# whose only reference was the create_task() call can be garbage collected
# before it reaches the data layer. Hold each one until it completes.
_persistence_tasks: set[asyncio.Task] = set()


def check_add_step_in_cot(step: "Step"):
is_message = step.type in [
Expand Down Expand Up @@ -342,7 +347,9 @@ async def update(self):

if data_layer:
try:
asyncio.create_task(data_layer.update_step(step_dict.copy()))
_task = asyncio.create_task(data_layer.update_step(step_dict.copy()))
_persistence_tasks.add(_task)
_task.add_done_callback(_persistence_tasks.discard)
except Exception as e:
if self.fail_on_persist_error:
raise e
Expand All @@ -367,7 +374,9 @@ async def remove(self):

if data_layer:
try:
asyncio.create_task(data_layer.delete_step(self.id))
_task = asyncio.create_task(data_layer.delete_step(self.id))
_persistence_tasks.add(_task)
_task.add_done_callback(_persistence_tasks.discard)
except Exception as e:
if self.fail_on_persist_error:
raise e
Expand All @@ -393,7 +402,9 @@ async def send(self):

if data_layer:
try:
asyncio.create_task(data_layer.create_step(step_dict.copy()))
_task = asyncio.create_task(data_layer.create_step(step_dict.copy()))
_persistence_tasks.add(_task)
_task.add_done_callback(_persistence_tasks.discard)
self.persisted = True
except Exception as e:
if self.fail_on_persist_error:
Expand Down Expand Up @@ -493,7 +504,9 @@ def __enter__(self):
self.parent_id = parent_step.id
local_steps.set(previous_steps + [self])

asyncio.create_task(self.send())
_task = asyncio.create_task(self.send())
_persistence_tasks.add(_task)
_task.add_done_callback(_persistence_tasks.discard)
return self

def __exit__(self, exc_type, exc_val, exc_tb):
Expand All @@ -508,4 +521,6 @@ def __exit__(self, exc_type, exc_val, exc_tb):
current_steps.remove(self)
local_steps.set(current_steps)

asyncio.create_task(self.update())
_task = asyncio.create_task(self.update())
_persistence_tasks.add(_task)
_task.add_done_callback(_persistence_tasks.discard)