[mythtv-users] Deleted recordings in mythweb

[Yianni]

> To: mythtv-users at mythtv.org
> From: mtdean at thirdcontact.com
> Date: Fri, 22 Jan 2016 17:09:57 -0500
> Subject: Re: [mythtv-users] Deleted recordings in mythweb
>
> On 01/22/2016 04:41 PM, Yianni wrote:
>
> Can you delete the already-deleted recordings from MythWeb? Do they
> actually disappear if you do?
>

Yes, I can and they do disappear (they were above 1000 when I noticed this thread, earlier). 
However, I was holding back from deleting all of them in case a developer wanted to use this as a
test case.

> What's happening is there's a race condition that can occur when
> deleting (especially large numbers of) recordings and shutting down
> mythbackend (uncleanly), that can result in some recordings getting into
> a limbo state where they're not fully deleted, but they were supposed to
> be, so MythTV ignores them thinking they will be gone soon, even though
> the deletion process was interrupted and nothing is working to delete
> them, anymore. All of the recordings in this state are ones that you've
> previously deleted, so you can re-delete them without problems.
>
> Technically, MythWeb's showing the recordings is a bug in MythWeb.
> However, since it does show them, if you can actually delete them from
> MythWeb, that's probably the best way to clean them up.

Thank God for bugs, then! I'd be wasting a huge amount of space
>
> Anyone with a large number of these probably got them when they upgraded
> to the version of MythTV that enabled the delete queue (Deleted
> recording group) for everyone. There was a bug for a couple of days in
> the initial implementation of the patch that resulted in all the
> recordings in the Deleted recording group being immediately removed upon
> upgrade and--most likely--this resulted in people and/or process
> monitors thinking MythTV was locked up, which probably resulted in a lot
> of processes getting killed and leaving these broken recordings.

You may be right (well, you usually are!) but I cannot completely verify this since
I removed a lot of the deleted recordings just before. Those that are still remaining in the 
Deleted group are between Jan, 2015 and Feb, 2015.

>
> And, FWIW, to the best of my knowledge, this race condition won't occur
> (or at least, the time period where it can occur is so much smaller that
> it will nearly never occur) for users who enable:
>
> Delete files slowly
> Some filesystems use a lot of resources when deleting large files. If
> enabled, this option makes MythTV delete files slowly on this backend to
> lessen the impact.
>
> So, to prevent more zombie recordings, anyone can enable that in
> mythtv-setup's General settings--whether you need it or not. There's not
> really a down side to enabling it, unless your backend happens to use
> NFS or CIFS to access its MythTV storage (in which case, you probably
> don't want it enabled).
>
> Mike

Thanks again for the explanation and the suggestion. I'll enable it during the weekend.

Yianni