Re: [bitbake-devel] [PATCH] asyncrpc: Close the client event loop when the client is collected

On Thu, Aug 6, 2026 at 9:13 AM Francisco Pedraza via lists.openembedded.org
<[email protected]> wrote:

> Client creates its own event loop and installs it with
> asyncio.set_event_loop(), so a client dropped without close() being
> called keeps the loop, and any transport that loop owns, alive. The
> loop only becomes collectable once a later client replaces the global
> reference, and asyncio then reports the transport and the loop as
> unclosed:
>
>   ResourceWarning: unclosed transport
> <asyncio.sslproto._SSLProtocolTransport object>
>   ResourceWarning: unclosed event loop <_UnixSelectorEventLoop
> running=False closed=False>
>
> This is why the warning shows up at an unrelated later point rather
> than where the client was leaked.
>
> SignatureGeneratorUniHashMixIn caches its client and only closes it
> from reset() and exit(), so any teardown path missing those leaks it.
>
> Register a weakref.finalize() to close the loop when the client is
> collected. close() detaches the finalizer first, so the explicit path
> does the same work as before.
>
> Reproduced with two clients where the first is never closed, on python
> 3.10 with websockets 10.4 and on python 3.14 with websockets 17.0.1.
> Both report the warnings without this change and neither does with it.
> bitbake-selftest hashserv.tests passes.
>
> Fixes [YOCTO #16236]
>
> Signed-off-by: Francisco Pedraza <[email protected]>
> ---
>  lib/bb/asyncrpc/client.py | 27 ++++++++++++++++++++++++---
>  1 file changed, 24 insertions(+), 3 deletions(-)
>
> diff --git a/lib/bb/asyncrpc/client.py b/lib/bb/asyncrpc/client.py
> index 17b72033b..115acd456 100644
> --- a/lib/bb/asyncrpc/client.py
> +++ b/lib/bb/asyncrpc/client.py
> @@ -12,6 +12,7 @@ import socket
>  import sys
>  import re
>  import contextlib
> +import weakref
>  from threading import Thread
>  from .connection import StreamConnection, WebsocketConnection,
> DEFAULT_MAX_CHUNK
>  from .exceptions import ConnectionClosedError, InvokeError
> @@ -224,8 +225,29 @@ class Client(object):
>          # required (but harmless) with it.
>          asyncio.set_event_loop(self.loop)
>
> +        # The loop and its transports must be closed even if the caller
> never
> +        # calls close(). Since set_event_loop() above replaces the
> reference
> +        # held by the previous client, an unclosed loop only becomes
> reachable
> +        # for collection once another client is created, at which point
> +        # asyncio reports "unclosed transport" and "unclosed event loop"
> +        # ResourceWarnings. The finalizer is detached by close() so that
> the
> +        # normal path is unaffected.
> +        self._finalizer = weakref.finalize(
> +            self, self._close_loop, self.loop, self.client
> +        )
> +
>          self._add_methods("connect_tcp", "ping")
>
> +    @staticmethod
> +    def _close_loop(loop, client):
> +        if loop.is_closed():
> +            return
> +        try:
> +            loop.run_until_complete(client.close())
> +            loop.run_until_complete(loop.shutdown_asyncgens())
> +        finally:
> +            loop.close()
> +
>      @abc.abstractmethod
>      def _get_async_client(self):
>          pass
> @@ -258,9 +280,8 @@ class Client(object):
>
>      def close(self):
>          if self.loop:
> -            self.loop.run_until_complete(self.client.close())
> -            self.loop.run_until_complete(self.loop.shutdown_asyncgens())
> -            self.loop.close()
> +            self._finalizer.detach()
> +            self._close_loop(self.loop, self.client)
>          self.loop = None
>
>      def __enter__(self):
> --
> 2.55.0
>
>
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