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Author Topic: Build thumbnails runs slower and slower  (Read 1980 times)

tiberiuspv

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Build thumbnails runs slower and slower
« on: December 17, 2014, 03:24:50 pm »

I just erased my library contents (included deleted items), and re-imported everything. About 51,000 tracks (some without cover art, all Audio, all JPEG, mostly 800x800 px). Very spiffy import, and completely clean data base.

Then I built the thumbnails database explicitly (from Tree & View options pane). At first, the progress was pretty fast (probably ~20 per second), and I let it run overnight. When I checked the progress this morning (about 10 hrs later), it was still at around 32,000 files and running at about 2 seconds per thumbnail, pegging a full CPU core (with a significant amount of time spent in the kernel). Quite puzzling. I canceled the thumbnail build, and restarted it (with 14000 to go). Similar behavior: very fast at first, mostly I/O bound. Less than 1/2 core used (10% of my i5). I'm am now at 5,000 out of 14,000, and the rate has dropped to about 5 per second, and the CPU is now at about 0.8 cores (20% of my i5). The memory footprint of MC remains small throughout (170 MB).

So there is something rather strange going on which makes the thumbnail build go more slowly within a single pass. Doing it in chunks behaves much better. Not a big issue, since this is not something done very often... But unexplained behavior is always worth taking a look at.

Note that I have no performance issue at all in normal use. MC is very fast except for this one thing, which is why it's puzzling.

Setup: i5-2405S (4 core single-threaded), 16 GB memory. MC library (database) on SSD, music tracks on HDD, all SATA-3. Windows 7 Pro, fully up to date; MC 20.0.49

Final side note: thanks for introducing Image Height/Width, I can now easily go through all my library and figure out which CD covers I need to scan... Online CD art is often not up to my standards :-)
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hulkss

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Re: Build thumbnails runs slower and slower
« Reply #1 on: December 23, 2014, 09:51:41 pm »

Similar behavior here, thumbnail building really slows down after the first thousand or so.
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marko

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Re: Build thumbnails runs slower and slower
« Reply #2 on: December 24, 2014, 12:16:52 am »

I've seen this happen if logging is enabled.

check logging. "Help > Logging". Uncheck "output to log file" and click on the "Done" button.

They should start flying after that. When building thumbs, that log file can get into 100's of MB of size.
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