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High ActiveRecord CPU Utilization

 
 
Brian Adkins
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      03-07-2007
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#quo te
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
....
 
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Brian Adkins
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      03-07-2007
Brian Adkins wrote:
> 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 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
 
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Sam Smoot
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      03-07-2007
On Mar 6, 10:18 pm, Brian Adkins <(E-Mail Removed)> wrote:
> Brian Adkins wrote:
> > 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 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


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...

 
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Brian Adkins
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Posts: n/a
 
      03-07-2007
Sam Smoot wrote:
> On Mar 6, 10:18 pm, Brian Adkins <(E-Mail Removed)> wrote:
>> Brian Adkins wrote:
>>> 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 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

>
> Ruby is a slowish language right now, but this isn't really Ruby's
> fault.


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
perspective.

> 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.


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.

> If you can't, you might try looking into some of the
> alternatives? It's a tough choice...


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

 
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Bill Kelly
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Posts: n/a
 
      03-07-2007
From: "Brian Adkins" <(E-Mail Removed)>
>
> If there's an alternative I haven't mentioned that you feel is actually
> viable as a contender, feel free to pass it on.


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:
http://rubyforge.org/pipermail/eventmachine-talk/
http://rubyforge.org/pipermail/event...ry/000395.html
http://rubyforge.org/pipermail/event...ch/000494.html
http://rubyforge.org/pipermail/event...ch/000510.html



Regards,

Bill


 
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khaines@enigo.com
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      03-07-2007
On Wed, 7 Mar 2007, Brian Adkins wrote:

> 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.


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


 
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Ben Bleything
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      03-07-2007
On Wed, Mar 07, 2007, Jeremy Kemper wrote:
> Hey Brian, could you start this conversation on the Rails list? It's a
> pretty narrow topic.


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

 
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Brian Adkins
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      03-07-2007
http://www.velocityreviews.com/forums/(E-Mail Removed) wrote:
> On Wed, 7 Mar 2007, Brian Adkins wrote:
>
>> 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.

>
> 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.


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

>
>
> Kirk Haines
>
>

 
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Brian Adkins
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Posts: n/a
 
      03-07-2007
Ben Bleything wrote:
> On Wed, Mar 07, 2007, Jeremy Kemper wrote:
>> Hey Brian, could you start this conversation on the Rails list? It's a
>> pretty narrow topic.

>
> 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
>


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
 
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Sam Smoot
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      03-07-2007
On Mar 7, 10:31 am, Brian Adkins <(E-Mail Removed)> wrote:
> (E-Mail Removed) wrote:
> > On Wed, 7 Mar 2007, Brian Adkins wrote:

>
> >> 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.

>
> > 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.

>
> 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
>
>
>
> > Kirk Haines


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
the
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
because
ActiveSupport and Facets step on each other (that's just what I gather
from
the nitro-general list). But I imagine contributing to resolve the
issues
between Og & Rails probably isn't as great an undertaking as making AR
faster.
Depending on Og's performance that may or may not be worthwhile I
suppose.

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

 
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