[SOLVED] Very slow Docker MySQL container

0x000000 · 2015-01-05 23:30:30

I'm running some MySQL migrations on a Docker container. This is the first time I've ever used Docker, but I'm both disappointed and confused by it. The migrations I need to run are just a bunch of CREATE and ALTER statements (probably in the hundreds). It's bananas slow in the Docker container, between 2-6 seconds for a create, sometimes as long as 15s for an ALTER. A migration that should take around one minute ends up taking around 30. I'm running an i7 with 16GB of memory, so I don't think this should be an issue. For what it's worth, I've never experienced poor performance like this on my local MySQL server.

I'm monitoring the situation with iotop and I see [jdb2/sdb2-8] and [jdb2/dm-1-8] up at 99% for IO. I don't know what's going on, nor do I really know where to start looking.

Last edited by 0x000000 (2015-01-06 16:19:07)

firecat53 · 2015-01-05 23:53:00

What storage driver are you using (see 'docker info')? If you are using devicemapper, which is the default unless you have an AUFS enabled kernel or a btrfs partition, I'd suggest creating a btrfs partition for /var/lib/docker and trying again. The btrfs and aufs storage backends are substantially faster in my experience.

Scott

0x000000 · 2015-01-06 16:12:30

Well, I had to run out and buy a new hard drive to make that happen, but wow, order of magnitude improvement. Thanks!

(should I mark this as solved? Buying a new hard drive doesn't seem like the best solution)

firecat53 · 2015-01-06 16:14:39

Heh Was it the new hard drive or the btrfs? In either case, I think solved would be appropriate.

0x000000 · 2015-01-06 16:18:51

Hard to know for sure, but I'm thinking btrfs. jbd2 wasn't going nuts on IO this time around.

firecat53 · 2015-01-06 17:28:08

If you've got anything really important in those containers, make sure you've got good backups and a UPS. My server got really hosed once after a power loss

Arch Linux

#1 2015-01-05 23:30:30

[SOLVED] Very slow Docker MySQL container

#2 2015-01-05 23:53:00

Re: [SOLVED] Very slow Docker MySQL container

#3 2015-01-06 16:12:30

Re: [SOLVED] Very slow Docker MySQL container

#4 2015-01-06 16:14:39

Re: [SOLVED] Very slow Docker MySQL container

#5 2015-01-06 16:18:51

Re: [SOLVED] Very slow Docker MySQL container

#6 2015-01-06 17:28:08

Re: [SOLVED] Very slow Docker MySQL container

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