Date: Mon, 02 Jan 2012 21:23:30 -0500 From: Robert Boyer <rwboyer@mac.com> To: Eduardo Morras <nec556@retena.com> Cc: "Muhammet S. AYDIN" <whalberg@gmail.com>, freebsd-questions@freebsd.org Subject: Re: freebsd server limits question Message-ID: <15170C4F-7142-479F-8C61-EC1F2D516441@mac.com> In-Reply-To: <BF32B73F-CFAB-4682-80E0-D7E4DE2E339A@mac.com> References: <CAP28s1DhhsSV%2Bz8BuRDVjHypD%2BpECuXQEH5BKjJRKMorcWL0rw@mail.gmail.com> <0LX600GBUUP8AWE1@ms02044.mac.com> <AD321296-15AC-493D-9885-DE29A70DA33B@mac.com> <BF32B73F-CFAB-4682-80E0-D7E4DE2E339A@mac.com>
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Just realized that the MongoDB site now has some recipes up for what you = really need to do to make sure you can handle a lot of incoming new = documents concurrently=85. Boy you had to figure this stuff out yourself just last year - I guess = the mongo community has come a very long way=85. Splitting Shard Chunks - MongoDB enjoy=85. RB On Jan 2, 2012, at 5:38 PM, Robert Boyer wrote: > Sorry one more thought and a clarification=85. >=20 >=20 > I have found that it is best to run mongos with each app server = instance most of the mongo interface libraries aren't intelligent about = the way that they distribute requests to available mongos processes. = mongos processes are also relatively lightweight and need no = coordination or synchronization with each other - simplifies things a = lot and makes any potential bugs/complexity with app server/mongo db = connection logic just go away. >=20 > It's pretty important when configuring shards to take on the write = volume that you do your best to pre-allocate chunks and avoid chunk = migrations during your traffic floods - not hard to do at all. There are = also about a million different ways to deal with atomicity (if that is a = word) and a very mongo specific way of ensuring writes actually "made it = to disk" somewhere =3D from your brief description of the app in = question it does not sound that it is too critical to ensure "every = single solitary piece of data persists no matter what" as I am assuming = most of it is irrelevant and becomes completely irrelevant after the = show- or some time there after. Most of the programing and config = examples make an opposite assumption in that they assume that each = transaction MUST be completely durable - if you forgo that you can get = screaming TPS out of a mongo shard. >=20 > Also if you do not find what you are looking for via a ruby support = group - the JS and node JS community also may be of assistance but they = tend to have a very narrow view of the world=85. ;-) >=20 > RB > On Jan 2, 2012, at 4:21 PM, Robert Boyer wrote: >=20 >> To deal with this kind of traffic you will most likely need to set up = a mongo db cluster of more than a few instances=85 much better. There = should be A LOT of info on how to scale mongo to the level you are = looking for but most likely you will find that on ruby forums NOT on = *NIX boards=85. >>=20 >> The OS boards/focus will help you with fine tuning but all the fine = tuning in the world will not solve an app architecture issue=85 >>=20 >> I have setup MASSIVE mongo/ruby installs for testing that can do this = sort of volume with ease=85 the stack looks something like this=85. >>=20 >> Nginix=20 >> Unicorn >> Sinatra >> MongoMapper >> MongoDB >>=20 >> with only one Nginix instance can feed an almost arbitrary number of = Unicorn/Sinatra/MongoMapper instances that can in turn feed a properly = configured MongoDB cluster with pre-allocated key distribution so that = the incoming inserts are spread evenly against the cluster instances=85 >>=20 >> Even if you do not use ruby that community will have scads of info on = scaling MongoDB. >>=20 >> One more comment related to L's advice - true you DO NOT want more = transactions queued up if your back-end resources cannot handle the TPS = - this will just make the issue harder to isolate and potentially make = the recovery more difficult. Better to reject the connection at the = front-end than take it and blow up the app/system. >>=20 >> The beauty of the Nginix/Unicorn solution (Unicorn is ruby specific) = is that there is no queue that is feed to the workers when there are no = workers - the request is rejected. The unicorn worker model can be = reproduced for any other implementation environment (PHP/Perl/C/etc) = outside of ruby in about 30 minutes. It's simple and Nginix is very well = suited to low overhead reverse proxy to this kind of setup. >>=20 >> Wishing you the best - if i can be of more help let me know=85 >>=20 >> RB >>=20 >> On Jan 2, 2012, at 3:38 PM, Eduardo Morras wrote: >>=20 >>> At 20:12 02/01/2012, Muhammet S. AYDIN wrote: >>>> Hello everyone. >>>>=20 >>>> My first post here and I'd like to thank everyone who's involved = within the >>>> FreeBSD project. We are using FreeBSD on our web servers and we are = very >>>> happy with it. >>>>=20 >>>> We have an online messaging application that is using mongodb. Our = members >>>> send messages to "the voice" show's (turkish version) contestants. = Our two >>>> mongodb instances ended up in two centos6 servers. We have failed. = So hard. >>>> There were announcements and calls made live on tv. We had +30K/sec >>>> visitors to the app. >>>>=20 >>>> When I looked at the mongodb errors, I had thousands of these: >>>> http://pastie.org/private/nd681sndos0bednzjea0g. You may be = wondering why >>>> I'm telling you about centos. Well, we are making the switch from = centos to >>>> freebsd FreeBSD. I would like to know what are our limits? How we = can set >>>> it up so our FreeBSD servers can handle min 20K connections = (mongodb's >>>> connection limit)? >>>>=20 >>>> Our two servers have 24 core CPUs and 32 GBs of RAM. We are also = very open >>>> to suggestions. Please help me out here so we don't fail deadly, = again. >>>>=20 >>>> ps. this question was asked in the forums as well however as = someone >>>> suggested in the forums, i am posting it here too. >>>=20 >>> Is your app limited by cpu or by i/o? What do vmstat/iostat says = about your hd usage? Perhaps mongodb fails to read/write fast enough and = making process thread pool bigger only will make problem worse, there = will be more threads trying to read/write. >>>=20 >>> Have you already tuned mongodb? >>>=20 >>> Post more info please, several lines (not the first one) of iostat = and vmstat may be a start. Your hd configuration, raid, etc... too. >>>=20 >>> L=20 >>>=20 >>> _______________________________________________ >>> freebsd-questions@freebsd.org mailing list >>> http://lists.freebsd.org/mailman/listinfo/freebsd-questions >>> To unsubscribe, send any mail to = "freebsd-questions-unsubscribe@freebsd.org" >>=20 >> _______________________________________________ >> freebsd-questions@freebsd.org mailing list >> http://lists.freebsd.org/mailman/listinfo/freebsd-questions >> To unsubscribe, send any mail to = "freebsd-questions-unsubscribe@freebsd.org" >=20 > _______________________________________________ > freebsd-questions@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-questions > To unsubscribe, send any mail to = "freebsd-questions-unsubscribe@freebsd.org"
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