Re: [PATCH] [gdb/python] Avoid queue.SimpleQueue for python 3.6

[Tom de Vries <tdevries@suse.de>]

On 1/5/23 16:19, Tom Tromey wrote:
>>>>>> "Tom" == Tom de Vries <tdevries@suse.de> writes:
> 
> Tom> Fixed by attached commit, any comments?
> 
> Thank you for working on this.  I saw your note yesterday but was too
> busy to address it.
> 
> Tom> +        if sys.version_info[0] == 3 and sys.version_info[1] <= 6:
> Tom> +            self.write_queue = queue.Queue()
> Tom> +        else:
> Tom> +            self.write_queue = queue.SimpleQueue()
> 
> It wasn't clear to me what happens with Queue if task_done is never
> called.  Like, does it "leak" memory?  This is why I chose SimpleQueue.
> 
> Maybe we can just switch to Queue entirely and have the popping code
> also call task_done immediately.  That seems ok since we don't use join.
> I guess what I would do here is have a helper module that uses
> SimpleQueue if it is available, and otherwise implements a look-alike
> using Queue.
> 
> I don't know if I can work on this today but I will get to it soon,
> unless you feel like trying it out.
> 
> If Queue can be dropped in like your patch without any negative effects,
> then that's also totally fine by me.

I agree that the semantics as advertised for task_done are a bit vague.

I read about it a bit here ( 
https://stackoverflow.com/questions/49637086/python-what-is-queue-task-done-used-for 
) to understand what it's supposed to do and looked at the 
implementation here ( 
https://github.com/python/cpython/blob/master/Lib/asyncio/queues.py ), 
and by now I'm convinced that there's no memory leak.

So I'll commit shortly.

Thanks,
- Tom