Possible memory leak in pika.BlockingConnection and pika.SelectConnection

[John Larson]

Hello!

I've been using Pika for a few months and I'm loving it. The BlockingConnection makes for really easy, Pythonic use, and it's nice to have the SelectConnection option for when I need to use it in a non-blocking manner.

One thing I've only run into recently is that when a BlockingConnection object or SelectConnection object is created, it doesn't seem to let go of the memory it uses, even if the connection is closed and I don't keep a reference to the connection object.

A minimal reproduction I've created for BlockingConnection

```

import pika

while True:

    pika.BlockingConnection().close()

```

Environment:

OS: macOS Catalina version 10.15.7 (19H2)

Python: 3.9.0

Pika: 1.1.0

RabbitMQ: 3.8.9, installed using docker, with the command `docker run -d -p 5672:5672 rabbitmq:3.8.9`

Expected behavior: If I view the process's memory usage, it will stay fairly level.

Actual behavior: When I view the process in macOS Activity Monitor, the process's memory usage increases over time, at a rate of about 0.5-1 MB/minute.

It also eats memory in a similar way when I run it in Amazon Linux. If you want, I can provide the environment details for that as well.

I considered using SelectConnection as a workaround, but I got similar results:

```

import pika

def on_connected(connection):

    connection.close()

def on_connection_closed(connection, exc):

    connection.ioloop.stop()

while True:

    connection = pika.SelectConnection(on_open_callback=on_connected)

    connection.add_on_close_callback(on_connection_closed)

    connection.ioloop.start()

```

Environment (Same as for BlockingConnection test):

OS: macOS Catalina version 10.15.7 (19H2)

Python: 3.9.0

Pika: 1.1.0

RabbitMQ: 3.8.9, installed using docker, with the command `docker run -d -p 5672:5672 rabbitmq:3.8.9`

Expected behavior: If I view the process's memory usage, it will stay fairly level.

Actual behavior: When I view the process in macOS Activity Monitor, the process's memory usage increases over time, at a rate of about 0.5-1 MB/minute.

Thanks for taking the time to look at this; if you got this far, you read a somewhat long message. :) Is there something I'm not doing correctly here? Is this a known bug?

Thanks,

John

[Luke Bakken]

Hi John,

Thanks for the very detailed report. I'll try to find time to investigate.

Luke

[John Larson]

Should I go ahead and file an issue on GitHub for this?

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[Luke Bakken]

Please do. I haven't yet had time to reproduce this.