commons-user mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "Hope, Matthew" <Matthew.H...@capitalone.com>
Subject RE: [lang] Reusable Builder classes
Date Wed, 01 Oct 2003 09:55:49 GMT
The end user may wish to consider whether their use case would benefit from
caching the calculated value...

If you can handle doing the coding of a dirty flag and its maintenance then
the only overhead is in a boolean, int (and possibly String if you want to
cache toString()) instance variable.

If the data rarely changes and the performance in this area is really what
matters this will provide far more bang for buck than just caching the
Builder Object.

But what everyone else said is the place to start - is this really what's
killing performance, what does profiling tell you?

Matt

-----Original Message-----
From: __matthewHawthorne [mailto:matth@phreaker.net] 
Sent: 30 September 2003 23:25
To: Jakarta Commons Users List
Subject: Re: [lang] Reusable Builder classes


Another quote I've heard: "premature optimization is the root of all 
evil."  I agree with what you're saying.

With the exception of some common sense situations, I think that 
performance optimizations carry the ability to pollute an API and mangle 
the internal code.  Garbage collection is improving, JVMs are getting 
faster... I'd prefer clean, maintainable code over that which goes to 
extremes to save a few milliseconds.

Measurements are a necessity for this sort of thing.  I think the 
problem has to be proven before the solution is started.  There's a nice 
profiler plugin for Eclipse that I've used a few times, it seems to do 
the job.




Gary Gregory wrote:

> Hi,
> 
> I am always very weary of doing anything in the name of performance 
> without any measurements based on a real usage scenario. Old motto on 
> performance
> improvements: First, don't' do it. Second, think about it, then don't do
it.
> ;-)
> 
> I think it would be interesting to discuss this if/when the post read 
> like: "In our app x, we've measured with JProbe (or whatever) a 
> bottleneck in this and that place were 80% of the time for a set of 
> tasks is spent in FooBuilder.doThisOrThat()."
> 
> There are two kinds of performance: speed and memory usage. Here we 
> are talking about creating code to change the profile and balance of 
> these two aspects based on a hunch. I have been to many performance 
> talks (JavaOne) where one hears things like (paraphrasing): "in an 
> extreme case, we had this customer try such and such performance 
> improvements of caching this and that in memory which effectively 
> negated GC from collecting anything and led to a different kind of 
> memory leak (a.k.a unwanted object retention) and performance 
> degradation due to virtual memory swapping".
> 
> From the POV of client code, this seems like quite a complication to 
> deal with, especially when considering MT issues.
> 
> Without talking sides on the details of this particular issue, when 
> designing an API, you also have to consider what choices you'll give 
> client code. At which point will the client code writer scratch his 
> head with a "there are so many ways of doing the same thing, which one 
> is best and when?". It is best if all of these choices are documented.
> 
> Gary
> 
> 
>>-----Original Message-----
>>From: Stephen Colebourne [mailto:scolebourne@btopenworld.com]
>>Sent: Tuesday, September 30, 2003 13:03
>>To: Jakarta Commons Users List
>>Subject: Re: [lang] Reusable Builder classes
>>
>>Possible I suppose. I guess I don't have strong views either for or 
>>against.
>>
>>Any other [lang] committers have any views?
>>
>>Stephen
>>
>>----- Original Message -----
>>From: "Don Forbes" <Don.Forbes@2cana.co.za>
>>I find the Builder classes really helpful, but find it wasteful having 
>>to create a new HashCodeBuilder, CompareToBuilder or EqualsBuilder for 
>>each invocation of a hashCode, equals or compareTo method.  In some 
>>situations, such as a sort of a large collection, these methods can 
>>end up being called often, thus imposing a high garbage collection 
>>overhead.
>>
>>I am thinking of something analogous to StringBuffer, which can be 
>>reset for reuse by simply calling setLength(0).
>>
>>How about a simple reset() method, with no parameters, that just 
>>resets the internal state (e.g. the variable "comparison" in the case 
>>of
>>CompareToBuilder) to its initial value?  (Possibly also a getter to 
>>determine whether the builder is currently in a reusable state.)
>>
>>Granted, this would require the Builder to be an instance variable of 
>>the calling object rather than a local variable, thus raising issues 
>>of thread safety.  Unfortunately using sychronized methods has 
>>something of a bad name for performance.  In my understanding and 
>>experience this is an unfair reputation, and my guess is that the 
>>overhead would be amply compensated for
>>by the savings in garbage collection.  But short of this, provided the
>>caller is given the responsibility for synchronising access to the object
>>in
>>a multithreading scenario, I don't see a problem.
>>
>>Any thoughts?
>>
>>
>>Don
>>
>>---
>>Outgoing mail is certified Virus Free.
>>Checked by AVG anti-virus system (http://www.grisoft.com).
>>Version: 6.0.515 / Virus Database: 313 - Release Date: 2003/09/01
>>
>>
>>---------------------------------------------------------------------
>>To unsubscribe, e-mail: commons-user-unsubscribe@jakarta.apache.org
>>For additional commands, e-mail: commons-user-help@jakarta.apache.org
>>
>>
>>
>>---------------------------------------------------------------------
>>To unsubscribe, e-mail: commons-user-unsubscribe@jakarta.apache.org
>>For additional commands, e-mail: commons-user-help@jakarta.apache.org
> 
> 



---------------------------------------------------------------------
To unsubscribe, e-mail: commons-user-unsubscribe@jakarta.apache.org
For additional commands, e-mail: commons-user-help@jakarta.apache.org
 
**************************************************************************
The information transmitted herewith is sensitive information intended only
for use by the individual or entity to which it is addressed. If the reader
of this message is not the intended recipient, you are hereby notified that
any review, retransmission, dissemination, distribution, copying or other
use of, or taking of any action in reliance upon this information is
strictly prohibited. If you have received this communication in error,
please contact the sender and delete the material from your computer.

---------------------------------------------------------------------
To unsubscribe, e-mail: commons-user-unsubscribe@jakarta.apache.org
For additional commands, e-mail: commons-user-help@jakarta.apache.org


Mime
View raw message