[mythtv-users] mythbackend still eats memory: the current status
Nick Morrott
knowledgejunkie at gmail.com
Thu May 21 15:17:04 UTC 2009
On 21/05/2009, David Lister <foceni at gmail.com> wrote:
> I'll talk about these graphs:
First, many many thanks for posting such a detailed and informative response.
> [1] http://www.insidethex.co.uk/mythtv/mbe-mem-usage-active-eit-disabled.png
> [2] http://www.insidethex.co.uk/mythtv/mbe-mem-usage-6months.png
<snip>
> If there was a real leak (i.e. memory allocation without free), the
> lowest BASE of the VSZ would be rising steeply in a linear manner.
> Especially noticeable on sbrk trim drops.
>
> As you can see on [2], during the whole 6 months, there was NO rise
> whatsoever. The bottom line is at 330k the whole time, i.e. no leak.
Graph [2] shows mythbackend running with passive EIT collection. The
mythbackend process was restarted a couple of times during that 6
month period. However, this is not marked on graph [2] or mentioned in
a previous message, and the poor labelling I've used makes it
challenging to match up gridlines to dates.
The most recent backend restarts per my logs were:
Starting up as the master server.
2009-03-29 14:21:21.316 mythbackend: MythBackend started as master server
Starting up as the master server.
2009-04-03 20:34:07.565 mythbackend: MythBackend started as master server
I've generated a new 8 week graph of my most recent data and uploaded
it to http://www.insidethex.co.uk/mythtv/mbe-mem-usage-2months.png.
You can see that since the most recent restart on 2009-04-03 VSZ
continually rises from 330MiB initally to 380MiB today (approx
1MiB/day). Whether is means anything is not for me to say.
> Graph [1] - is that one process without interruption? If so, then again,
> no leak - perhaps there's the slightest 1k rise towards the end, but
> that's just too little for too short a time to call it a leak. If you
> mean the big sawtooth, it's properly freed to the OS eventually, that is
> not what you call a leak. If the graph begins with mythbackend startup,
> this peak could even be associated with some initial data collection,
> (custom?) allocator trim kicking in for the first time after initial
> estimations, or whatever - it's irrelevant, because it's freed.
Graph[1] relates to last year and shows the difference in usage with
active EIT enabled (first half of graph) and then disabled (second
half). The mythbackend process was restarted on 2008-07-15 and
resulted in much flatter memory usage. The graph therefore shows two
processes
Cheers,
Nick
--
Nick Morrott
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