[mythtv-users] Limit concurrent instances of mythpreviewgen?
Will Dormann
wdormann at gmail.com
Tue May 13 15:42:25 UTC 2014
Hi folks,
Ok, so one other area where the Atom processor is a bit weak for mythtv:
When I view recordings via mythweb, if it's been a while and I have a
lot of new recordings, mythweb/mythtv tries to run mythpreviewgen in
parallel for each new recording. I've seen at least 20 concurrent
instances of the mythpreviewgen process. And for a system that has 2
physical cores, *each* of these ends up timing out and I end up with
broken thumbnails.
I can either reload the page many times repeatedly until eventually it
starts to catch up. Or I can select a single recording title to
manually ensure that no more than 1 or 2 instances are executed at the
same time.
People with beefier systems may not notice these symptoms, but I think
it's a minor architectural problem with mythtv/mythweb (I haven't yet
looked into which may be at fault, but I suspect the latter)
Possible solutions might be to either:
1) Limit concurrent instances of mythpreviewgen to e.g. the number of
cores present on the system. This could perhaps be accomplished by
modifying mythweb, or replacing "mythpreviewgen" with a wrapper script
that internally handles concurrency issues.
2) Automatically generate the thumbnails used by mythweb (and mythtv?
Are they the same?) when a recording is finished, rather than on-demand.
The cost of generating the thumbnail is relatively low, so why not do
it as the recordings are made? Doing it on-demand just seems to
decrease responsiveness.
Thoughts? Before I dig into this, is this something that has already
been addressed in perhaps some setting that I'm unaware of?
Thanks
-WD
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