[issue41794] Memory leak in asyncio server
Change by Bale : -- components: asyncio nosy: EmperorBale, asvetlov, valid22, yselivanov priority: normal severity: normal status: open title: Memory leak in asyncio server type: behavior versions: Python 3.8 ___ Python tracker <https://bugs.python.org/issue41794> ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue41794] Memory leak in asyncio server
New submission from Bale :
In the file I attached below is a pretty simple asyncio server, it is identical
to the echo server on the documentation except it does not disconnect after
echoing.
When a connection is received, it creates an object called "test object" and
the only reference to that object is on the local scope. If all is working
properly, when the handler function returns the test object should also be
deleted, but I noticed the __del__ method is not being called, indicating
python is not deleting it. It seems like a reference to the frame of the
handler is being kept in a list (not sure where) and it is not being removed
from it.
Here is example code of how to trigger the bug:
s = socket.socket();s.connect(("127.0.0.1", ));s.send(b"test\0")
s.close()
By sending data and closing afterwards WITHOUT using s.recv() causes the issue,
what's interesting is that if we call s.close() immediately after sending, the
object is deleted by the server and everything works as intended. Calling
s.close() a few seconds after, causes the bug to happen. It should also be
noted that if I call s.recv() before s.close(), the bug does not happen.
What's more interesting is that when I run the above code in my python3.5
interpreter the bug does not get triggered, no matter what I do. The bug does
also not happen when I run it in a python3.8 interpreter on my windows
computer. When I run on the code on ubuntu on a python3.8 interpreter, the bug
is triggered.
--
Added file: https://bugs.python.org/file49460/test_server.py
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[issue41794] Memory leak in asyncio server
Bale added the comment: Also, if this is intended behavior and there is something that I am missing, you should really make it more clear in the documentation. In every project I found on github that uses asyncio.start_server, the bug exists -- ___ Python tracker <https://bugs.python.org/issue41794> ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue41794] Memory leak in asyncio server
Bale added the comment:
Ok since nobody is replying, the bug seems to be that if the asyncio server
sends data, and I do not use s.recv() to clear the buffer, and I use s.close()
instead, a reference to handle_echo is kept and is never deleted.
Using gc.collect() does delete the leaked object.
The socket that you use to connect to the server seems to also determine
whether the bug works, like how I can not do it when I create the connection on
my windows computer, but the bug is triggered when I do it on my ubuntu server.
I should also mention that I am running the asyncio server on my ubuntu server,
on python 3.8.
Here is output of the bug happening.
FROM CLIENT ON MY WINDOWS COMPUTER ON PY3.8:
>>> s = socket.socket()
>>> s.connect(("x.x.x.x", ))
>>> s.send(b"test")
4
# Wait for server to send data, but dont use s.recv(), just assume
>>> s.close()
Server output:
Received 'test' from ('x.x.x.x', 42241)
Send: 'test'
connection lost
DELETED OBJECT
After connection was lost, DELETED OBJECT was printed, so everything worked
fine. But when I create the socket in a different environment, such as on
ubuntu python 3.8:
Client side code (exact same as before):
>>> s = socket.socket()
>>> s.connect(("x.x.x.x", ))
>>> s.send(b"test")
4
# Wait for server to send data, but dont use s.recv(), just assume
>>> s.close()
Server side output:
Received 'test' from ('x.x.x.x', 42249)
Send: 'test'
connection lost
We can see that connection lost was printed, but DELETED OBJECT was not. This
is evidence that there is a memory leak bug with asyncio.start_server
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