High ActiveRecord CPU Utilization

Discussion in 'Ruby' started by Brian Adkins, Mar 7, 2007.

  1. Brian Adkins

    Brian Adkins Guest

    When running a test that primarily involves loading up a few MySQL
    tables with ActiveRecord objects, I was surprised to see the Ruby CPU
    utilization at 93% and the MySQL CPU utilization at 7%. I would expect
    this workload to be heavier on MySQL than that.

    I would think inserts (particularly with updating several foreign key
    indices) would tax the database more than Ruby.

    Has this been other folks' experience? Is running in the test
    environment incredibly different than production with respect to CPU
    utilization? I suppose my next step is to run in production to see what
    kind of results I get.

    I'm running the test from the root of my Rails project via:

    ruby test/unit/foo.rb

    Here's part of the profiler output:

    time name
    7.96 ActiveRecord::ConnectionAdapters::Quoting.quote
    5.61 ActiveRecord::Base#read_attribute
    5.15 ActiveRecord::Base#column_for_attribute
    4.25 ActiveRecord::Base#connection
    3.74 Hash#[]
    3.58 Array#each
    3.30 ActiveRecord::ConnectionAdapters::MysqlAdapter#quote
    3.16 ActiveRecord::ConnectionAdapters::Column#type_cast
    2.84 Module#===
    2.65 ActiveRecord::Base#clone_attribute_value
    2.29 ActiveRecord::Base#write_attribute
    2.24 Kernel.class
    2.22 Hash#each
    2.08 String#to_s
    2.03 ActiveRecord::Base#quote_value
    1.59 Kernel.send
    1.55 Array#include?
    1.52 Kernel.==
    1.48 ActiveRecord::Base#unserializable_attribute?
    1.39 Class#read_inheritable_attribute
    1.34 Kernel.clone
    1.29 ActiveRecord::Callbacks.notify
    1.15 ActiveRecord::Base#method_missing
    1.08 ActiveRecord::Base#columns_hash
    1.08 ActiveRecord::Base#respond_to?
    1.08 ActiveRecord::Callbacks.callback
    0.99 Kernel.eval
    0.95 Symbol#===
    0.90 Observable.notify_observers
    0.88 ActiveRecord::ConnectionAdapters::Column#text?
    0.85 Hash#[]=
    0.85 Class#inheritable_attributes
    0.83 Kernel.kind_of?
    0.81 ActiveRecord::Base#convert_number_column_value
    Brian Adkins, Mar 7, 2007
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  2. Brian Adkins

    Brian Adkins Guest

    I just moved my test code into a controller and ran it via:

    mongrel_rails start -e production

    Similar CPU characteristics except that Mongrel wasn't able to fully
    utilize my dual core CPU (I suppose because of the serialization of
    Rails code due to lack of thread safetyness).

    So the unit test (1093 records -> table1, 1093 records -> table2, 1
    record -> table3) took 5.5 seconds to complete and the identical test in
    a controller with Mongrel in production mode took 27.4 seconds!

    Yeah, I know I can have a cluster of Mongrel processes, and that's how I
    run for real, but I'm still a little bummed with these results :(

    I've switched my company's development from 100% Java to 100% Ruby, and
    I still believe that was a good decision because of productivity gains
    and joy, but I do miss some of the runtime performance of Java and the
    ease with which I could spin up a thread to do some background process.
    I'm glad BackgrounDRB has been provided, but it's not quite the same.

    Hopefully future versions of Ruby/Rails will provide some more runtime
    performance and concurrency - I'd be glad if I could just fork in Rails
    without trouble, but I don't think that's the case.

    For now, I don't have more customers than a Core 2 Duo can handle, so
    it's not exactly on the critical path for me yet :) In fact, I'm glad
    MySQL isn't on the critical path because overcoming that seems much more
    difficult than having a bunch of Apache/Mongrel processes running.

    Brian Adkins, Mar 7, 2007
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  3. Brian Adkins

    Sam Smoot Guest

    Ruby is a slowish language right now, but this isn't really Ruby's
    fault. Rails is just incredibly slow, and the problem only seems to be
    getting worse. You could spend some time trying to speed it up, but
    there's some really broad design decisions that make that pretty
    difficult. If you can live with the performance, then I guess I'd just
    do so with the expectation that a future release will improve
    performance. If you can't, you might try looking into some of the
    alternatives? It's a tough choice...
    Sam Smoot, Mar 7, 2007
  4. Brian Adkins

    Brian Adkins Guest

    Yeah, I remember when I first saw the computer language shootout stats!
    I was bummed that my new favorite language performed so poorly, but then
    I recalled the early days of Java (I started with 1.02) and gained some
    I'm pretty sure I can live with the performance - I think a few fast web
    server machines in front of a fast MySQL machine will do fine, and I'm
    not close to needing that yet.
    When I switched from Java to Ruby, I knew I was giving up some runtime
    performance and gaining much in other areas. Then I discovered Lisp and
    realized, "wow, it's powerful *and* fast" :) However, I think it would
    take too much work for me to get a Lisp environment to the point of
    being as productive for me as Ruby on Rails is currently (reminds me of
    Python web dev several years ago, maybe older), and I really do enjoy
    programming in Ruby.

    Python is a fair amount quicker than Ruby, but I like Ruby better, and
    the speed difference doesn't appear to be huge - I did get used to the
    white space, but I still don't like it in principle. It's interesting
    that I learned Python first, but at the time (2 to 3 yrs ago), I didn't
    feel the web frameworks were ready, so I jumped into Ruby via Rails
    (common story) and then discovered that I like the feel of the language
    better - it has some warts, but it's still a blast to program in. The
    Python frameworks seem to have progressed significantly since then.

    I just took a look at Smalltalk, but despite Seaside's success, I don't
    think it's quite ready (plus I just got away from an IDE heavy
    environment with Eclipse), and despite the super duper IDE capabilities,
    I don't feel it warrants the learning effort for me now - maybe later.

    So all in all, I'm pretty darn happy with Ruby/Rails at present. I have
    been on a language research blitz recently though (many, many hours) - I
    think it's motivated by Ruby's strengths and not its weaknesses. The
    logic goes something like this, "I was surprised about how much better
    Ruby is than Java, so I wonder if I could make that kind of jump again"
    - I guess I'm just greedy, not to mention susceptible to "the grass is
    always greener on the other side of the fence"

    I must say that everything I've read about Paul Graham's Arc indicates I
    would be very pleased with it. No idea when it will be completed, but
    I'd say it has a great shot at getting some traction.

    If there's an alternative I haven't mentioned that you feel is actually
    viable as a contender, feel free to pass it on.

    Brian Adkins, Mar 7, 2007
  5. Brian Adkins

    Bill Kelly Guest

    Not sure about a viable alternative; but from what you've said
    I thought you might find some of Kirk Haines' posts in the last
    month or two on the Eventmachine mailing list interesting:


    Bill Kelly, Mar 7, 2007
  6. Brian Adkins

    khaines Guest

    No, that isn't surprising. Any ORM trades CPU utilization outside of the
    database for convenience in the data representation. AR is fairly
    heavyweight in that regard, so it's doing a lot of work to give you the
    API that it does. Latency to a database can be a significant bottleneck
    to some applications, but relatively speaking, CPU utilization by the db
    will usually be a small fraction of the CPU utilization of the ORM using
    application that is talking with the db.

    Kirk Haines
    khaines, Mar 7, 2007
  7. For what it's worth, I'm using AR extensively outside rails and would
    have missed this had it started on the Rails list. I like it when AR
    discussions happen here ;)

    Ben Bleything, Mar 7, 2007
  8. Brian Adkins

    Brian Adkins Guest

    I agree about ORMs trading CPU for convenience, but I've used other ORMs
    (such as Hibernate with Java), and I don't recall the CPU ratio to be
    quite so high. In fact, my prior experience has always been that a piece
    of code such as I'm using would be database bound, and not CPU bound. I
    mean, seriously, all the code is doing is a bunch of database inserts!

    Also, since I'm not using stored procedures with Rails, MySQL has to
    work harder to parse the statements, so if stored procedures were used,
    the Rails/MySQL CPU ratio would be even higher than 93/7.

    Frankly, it's not worth my time to whip up a Java/Hibernate example for
    comparison, but I'm pretty darn curious now - both at what the CPU ratio
    would be as well as the time for completion.

    I'm willing to live with it, but that doesn't mean I have to like it :)
    Brian Adkins, Mar 7, 2007
  9. Brian Adkins

    Brian Adkins Guest

    I never saw Jeremy's message :( I don't know if the problem is with my
    ISP (Bellsouth DSL) or my mail reader (Thunderbird), but this isn't the
    first time that I've missed a relevant message. It makes me wonder how
    many other posts aren't getting through.

    Anyway, Jeremy, I actually did search for a rails newsgroup and
    Thunderbird didn't show any newsgroups with rails in the name except for
    (msn.onstage.motorsite.offroad.favtrails) :) So I did try, then I
    searched this newsgroup and noticed a fair amount of Rails related
    posts, so I thought it would be ok to post it here. Also, in this case,
    even though Rails may be slow, I do think the speed of Ruby is an
    important factor in my results.

    If you can point me to the Rails newsgroup, I'll try subscribing even if
    it doesn't show in Thunderbird. If you're referring to a mailing list
    instead, that is less desirable to me, but I could make use of it for
    Rails posts that are less relevant to Ruby.

    Brian Adkins, Mar 7, 2007
  10. Brian Adkins

    Sam Smoot Guest

    I'd definitely echo the perception that AR is unreasonably taxing on
    the CPU.
    Because it is. Performance just hasn't been a focus for it. Load up
    1,000 AR
    records with 10 attributes and you've got 10,000 strings to represent
    column names. That's just one example. I'd expect Og to be faster, but
    that's just a guess since I haven't actually benchmarked it.

    I wasn't trying to imply looking at other languages, just maybe other
    techniques. As I understand it Og+Rails has some issues right now
    ActiveSupport and Facets step on each other (that's just what I gather
    the nitro-general list). But I imagine contributing to resolve the
    between Og & Rails probably isn't as great an undertaking as making AR
    Depending on Og's performance that may or may not be worthwhile I

    One other thing to consider though: MySQL is the fastest mainstream
    I know of by a large margin, especially concerning INSERT and UPDATE
    performance. So if you were using Oracle or MSSQL before, that would
    the results a bit more.
    Sam Smoot, Mar 7, 2007
  11. Brian Adkins

    Avdi Grimm Guest

    The best place to look for ruby-related mailing lists and newsgroups
    is http://www.ruby-forum.com/. You can find a link to the Rails
    mailing list from there. You may find it easier to use the ruby-forum
    frontend, though, because it's a very high-volume list.

    That said, I concur that ActiveRecord has wider applicability than
    just Rails, and I find this an interesting topic of discussion.
    Avdi Grimm, Mar 7, 2007
  12. Brian Adkins

    zdennis Guest

    What is your script doing? Can you post it?

    I think depends on more of what you're doing and how you're doing it.
    I've seen CPU and memory issues with AR before, but these have all
    been fixed by understanding how and when to do things in AR (and in
    ruby). This also depends on the hardware differences between your
    development, test and production environments. Disk speed, memory and
    CPU(s) can have alot to do with the change between the environments.
    What your program is doing and how it is doing it will give more
    insight into your issue then just profiler output. Have you isolated
    the problem to a particular block of code?

    zdennis, Mar 8, 2007
  13. Yes, I'd like to see this discussion continue on the Ruby list, because
    there are some things to be learned from experiences with ActiveRecord.
    So, some questions for Brian:

    1. What's your platform, and what version of Ruby are you running?
    2. Is it possible for you to abstract a subset of your application as a
    benchmark, suitable for profiling?
    3. Is it "simple enough" that it will "probably work" with the recent
    jRuby implementation of Rails?
    M. Edward (Ed) Borasky, Mar 8, 2007
  14. Brian Adkins

    Brian Adkins Guest

    I created a smaller test that I could post that exhibits the same

    class PerfTestController < ApplicationController
    def index
    t1 = Time.now
    3000.times do
    member = Member.new
    member.first_name = 'Fred'
    member.last_name = 'Flintstone'
    member.address1 = '123 High St.'
    member.city = 'Reykjavik'
    member.state = 'Michigan'
    member.email = ''
    t2 = Time.now
    puts "Time elapsed = #{t2-t1}"

    That took 35.7 seconds (84 inserts per second) on a dual core 2 GHz AMD
    Opteron. It pegged Mongrel and MySQL didn't break a sweat.

    I just ran another test with a short ruby program inserting records
    directly using the mysql gem and it only took 1.6 seconds (1,875 inserts
    per second!), and the CPU utilization was as it should be - the MySQL
    CPU was ten times as much as Ruby. So it definitely appears that
    Rails/ActiveRecord is about 22 times as slow than a straight Ruby
    program - wow!

    This result makes me feel much better since the performance of Ruby
    seems fine. The fact that Rails/ActiveRecord is way slow isn't hurting
    me yet, and there is hope it can be sped up since it doesn't appear to
    be an inherent problem with Ruby.

    Here's the schema for Member:

    create table members (
    id int not null auto_increment,
    created_at datetime not null,
    updated_at datetime not null,
    first_name varchar(30) null,
    last_name varchar(30) null,
    address1 varchar(50) null,
    address2 varchar(50) null,
    city varchar(30) null,
    state varchar(5) null,
    email varchar(100) null,
    home_phone varchar(25) null,
    primary key(id)
    ) engine=InnoDB;
    I respectfully disagree. It was the profiler output that showed me where
    the time was being spent. I truncated the profiler output before it even
    got to my code - it was all Rails code.
    Brian Adkins, Mar 8, 2007
  15. Brian Adkins

    Brian Adkins Guest

    $ ruby -v
    ruby 1.8.4 (2005-12-24) [i486-linux]

    $ uname -a
    Linux airstream 2.6.17-11-generic #2 SMP Thu Feb 1 19:52:28 UTC 2007
    i686 GNU/Linux

    $ rails -v
    Rails 1.2.1

    I'm running Ubuntu 6.10
    Well, the "application" in this case is just a simple test for
    benchmarking :) See my previous post for the Rails controller code
    (what little there is of it).
    I would hope so - it doesn't get much simpler.
    Brian Adkins, Mar 8, 2007
  16. Is this being run in development mode, still? Dev mode does database
    reflection pretty often -- you might be getting pinged by that.
    Devin Mullins, Mar 8, 2007
  17. Brian Adkins

    Brian Adkins Guest

    Nope, it's running in the production environment.

    mongrel_rails start -e production
    Brian Adkins, Mar 8, 2007
  18. A couple of suggestions here:

    1. Download the latest Ruby source -- 1.8.6 pre something.
    2. Compile it for your architecture -- set CFLAGS = "-O2 -march=xxx"

    where "xxx" is your architecture -- it's an AMD64 of some kind, right?

    If you're running a 64-bit system, make sure you have a recent
    64-bit kernel and GCC 4.1 -- older compilers suck wet dog fur on the 64
    bit machines.

    That should get you somewhere in the 10 - 30 percent speed improvement
    over a 486-compiled Ruby 1.8.4. It might be more, but just doing the
    1.8.6 and the -O2 / march= stuff is pretty much mandatory.
    That should be OK -- most likely it's user time anyhow, not kernel time.
    That should be fine too. The compiler is probably more important.
    I know Charles Oliver Nutter reads this list -- he's looking for tests
    for the latest jRuby/Rails.
    M. Edward (Ed) Borasky, Mar 8, 2007
  19. Brian Adkins

    Brian Adkins Guest

    Interesting. Do you mind if I ask where you got the 10 to 30% figure?
    Stability is more important to me than raw speed, so I'd prefer to not
    use anything newer than Ruby 1.8.5-p12.

    I'm running a 32 bit kernel because 64 bit was, let's say, problematic.
    My gcc is 4.1.2.
    Brian Adkins, Mar 8, 2007
  20. ------=_Part_212542_25214727.1173336304234
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    Hi Brian,

    I wrapped this up in a simple script that anyone with MySQL or SQLite
    and the AR gem can run. It benchmarks AR create vs using the db
    connection directly. See attached.

    Excerpted results on a new MacBook Pro:
    user system total real
    raw quoted 0.460000 0.000000 0.460000 ( 0.480184)
    create 2.760000 0.080000 2.840000 ( 3.225227)

    (Nearly 7 times slower.) I haven't tried profiling the methods yet.

    In my experience with typical Rails apps, you'll hit a wall with ERB
    template rendering much sooner than with Active Record creation. This
    is an interesting pursuit nonetheless -- I'm interested to see what
    you all come up with.

    Best regards,

    Content-Type: application/octet-stream; name=ar_bench.rb
    Content-Transfer-Encoding: base64
    X-Attachment-Id: f_ez0u2y1j
    Content-Disposition: attachment; filename="ar_bench.rb"


    Jeremy Kemper, Mar 8, 2007
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