EntityCondition factory objects

[Adrian Crum]

On 6/10/2010 1:08 AM, David E Jones wrote:
> I'm sure there are good references around with a more complete list of differences.

I was referring to my example, not Lists in general.

> Be careful about pushing some differences and leaving out others, especially when bias is involved (ie arrays are better than linked lists). It may be that in some circumstances iterating is faster, but if so probably not by much (ie the difference between following a pointer versus incrementing an index).
>
> There are some things that linked lists do far better (like sorting, and most modifications actually), and if not intentionally optimized they can actually require more memory instead of less for smaller lists.

Actually, some of those differences are well documented. The performance
of various List implementations can be expressed mathematically, and
that information can be found in the JavaDocs.

> To Scott's point... what (again) was the point of all of this? I guess it's always fun to thump one's chest and demonstrate knowledge of the concepts behind basic data structures, but most of this stuff fits into freshman computer science material, so even that isn't so much fun s not many people will be impressed.

Remarks like this do little to advance the sharing of information.
Instead, they tend to squelch any further discussion.

I gave a simplified example to demonstrate what I was talking about. I
wasn't trying to appear superior. It's true that "most of this stuff
fits into freshman computer science material" - but I'm not going to
assume that everyone on this list has a Computer Science degree.

> To your point Adrian, this stuff is definitely an issue, but unless you're looking at a specific piece of code and you actually profile to test alternatives it's really quite difficult to guess at what is better.

Profiling can reveal bottlenecks, but it sounds like you're saying that
*only* profiling will reveal performance differences in different
designs. Like I said earlier, some of those performance differences can
be expressed mathematically.

Getting back to the main point of this discussion - classes should be
chosen based on their design and intended use. I'm not advocating
premature optimization, I'm saying that an informed choice will
generally perform better than an uninformed choice (copy-and-paste
development, or using a Javolution class just because it has Fast in its
name).

I look at it like the gas mileage I get with my car. If my mileage
drops, there are things I can do to improve it that are common
knowledge. I can check the air pressure in my tires to see if they are
under-inflated. I can clean the 50 pounds of clutter out of my trunk. I
can replace a clogged air filter. I don't need to connect my car to
diagnostic equipment to verify if those things improve my mileage -
because it's common knowledge that they do. If I do all of the common
knowledge things and my mileage continues to degrade, *then* I can
connect diagnostic equipment to it to find out the cause.

> That's part of the fun of profiling, the moment you find you were wrong is roughly the same moment when you find out what is right, even if it's often not what you expected. There are very few activities in life where those two events occur so close together... so it makes it kind of fun and only occasionally frustrating instead of the other way around... ;)
>
> -David
>
>
> On Jun 10, 2010, at 1:49 AM, Adrian Crum wrote:
>
>> Oops, I forgot to explain iteration differences. Iterating over an array is faster than traversing a doubly-linked list.
>>
>> -Adrian
>>
>> --- On Thu, 6/10/10, Adrian Crum<[hidden email]>  wrote:
>>> I backed it up in an indirect way by
>>> mentioning the need to understand the Javolution library and
>>> its intended use. Go here to find out more:
>>>
>>> http://javolution.org/
>>>
>>> To summarize: Javolution was intended to be used in
>>> real-time systems where timing is critical. The library's
>>> goal is timing that is *consistent*, not necessarily fast.
>>>
>>> OFBiz is not a real-time application - it isn't being used
>>> to control robots or Mars rovers or anything timing-critical
>>> like that.
>>>
>>> You have to spend time on the Javolution site and poke
>>> around in their code a bit to understand the
>>> advantages/disadvantages. Adam has mentioned some of them in
>>> this thread and in previous threads.
>>>
>>> FastList implements a doubly-linked list. The list nodes
>>> are kept in an object pool. ArrayList wraps an array. If you
>>> think about it, the advantages/disadvantages will start to
>>> become evident. FastList will perform additions and removals
>>> more consistently than ArrayList because the change involves
>>> adding/removing a node. ArrayList resizes/copies the array
>>> it wraps, so the timing depends on the size of the array. A
>>> doubly-linked list will take more memory than ArrayList
>>> because the list elements are wrapped with nodes. An
>>> ArrayList will take more memory than the array it wraps
>>> because it contains additional bookkeeping data.
>>>
>>> -Adrian
>>>
>>>
>>> --- On Wed, 6/9/10, Scott Gray<[hidden email]>
>>> wrote:
>>>
>>>> From: Scott Gray<[hidden email]>
>>>> Subject: Re: Discussion: When To Use Javolution (was:
>>> EntityCondition factory objects)
>>>> To: [hidden email]
>>>> Date: Wednesday, June 9, 2010, 11:56 PM
>>>> Interesting post but what I'm not
>>>> hearing is any mention of specific downsides to using
>>>> javolution in place of the util classes even when the
>>> use
>>>> may not be taking advantage of any specific
>>> javolution
>>>> features.
>>>>
>>>> You mention this:
>>>>> There is no performance benefit to using FastList
>>> in
>>>> this scenario. An ArrayList will use less memory and
>>> will
>>>> perform faster than FastList - if its size is
>>> initialized to
>>>> the correct value. Better yet, if you know the number
>>> of
>>>> objects in advance, then just create an array.
>>>>
>>>> But you provide no evidence to back the statement
>>> up.
>>>> And a FastList can also be given an initial size.
>>>>
>>>> I'm disagreeing with what you're saying because I
>>> really
>>>> don't know much about it, but your post doesn't really
>>> do
>>>> much to increase my knowledge or give me any reason
>>> to
>>>> follow your advice.
>>>>
>>>> Regards
>>>> Scott
>>>>
>>>> HotWax Media
>>>> http://www.hotwaxmedia.com
>>>>
>>>> On 10/06/2010, at 6:25 PM, Adrian Crum wrote:
>>>>
>>>>> I'm continuing this discussion with a new
>>> subject
>>>> since the thread is starting to diverge from the
>>> original
>>>> subject.
>>>>>
>>>>> A lot of the current code uses Javolution classes
>>> in
>>>> many places for one common reason - copy-and-paste
>>>> development. If you don't understand the Javolution
>>> library
>>>> and its intended use and actual benefits then it's
>>> hard to
>>>> know when the classes should be used and when there
>>> might be
>>>> better alternatives.
>>>>>
>>>>> When I see class names like FastList and FastMap,
>>> I
>>>> assume using them will speed up code. Indeed, some JRE
>>> class
>>>> methods will execute faster using Javolution instead
>>> of JRE
>>>> classes, and those methods are well documented on the
>>>> Javolution website. If a bit of code doesn't use any
>>> of
>>>> those methods, then there will be no benefit to using
>>>> Javolution.
>>>>>
>>>>> Adam and I discussed earlier the use of object
>>> pools.
>>>> Object pools used to improve performance because they
>>> helped
>>>> cut down on garbage collection. Sun/Oracle recommends
>>>> getting rid of object pools when using the newer
>>> versions of
>>>> Java because the newer versions have improved garbage
>>>> collectors.
>>>>>
>>>>> If you do a Google search for "java performance
>>>> improvement" you'll get a lot of links to a lot of
>>> articles.
>>>>  From my experience a lot of those ideas are based on
>>> some
>>>> special knowledge of how the JVM works and they "game
>>> the
>>>> system" to improve performance. As a result, some of
>>> those
>>>> optimizations depend on the JVM version and the
>>> platform it
>>>> runs on.
>>>>>
>>>>> My preference is to use efficient algorithms and
>>> well
>>>> structured code, and leave the performance
>>> optimizations to
>>>> the JVM. I can give an example that will be obvious
>>> to
>>>> everyone:
>>>>>
>>>>> Let's say a section of code builds a List of
>>> objects
>>>> and then iterates over the List. Once the List is
>>> created,
>>>> its contents don't change - there are no additions,
>>>> removals, inserts, etc. In addition, this List will be
>>> a
>>>> member of an object that is kept in a cache.
>>>>>
>>>>> There is no performance benefit to using FastList
>>> in
>>>> this scenario. An ArrayList will use less memory and
>>> will
>>>> perform faster than FastList - if its size is
>>> initialized to
>>>> the correct value. Better yet, if you know the number
>>> of
>>>> objects in advance, then just create an array.
>>>>>
>>>>> If an ArrayList is used, you can call the
>>> trimToSize
>>>> method after the List is filled to reduce the memory
>>> it
>>>> uses. Better yet, convert it to an array to reduce
>>> memory
>>>> use even more. A cached object that contains an array
>>>> instead of FastList will take less memory and perform
>>>> better.
>>>>>
>>>>> So, the main idea is to think about how the
>>> collection
>>>> is being used and then choose the best class for it.
>>> Don't
>>>> assume a Javolution class will always perform better.
>>>>>
>>>>> By the way, I'm not pointing any fingers or
>>> talking
>>>> down to anyone here. I've done the copy-and-paste
>>>> development myself. It's only recently that I started
>>> to
>>>> scrutinize my choice of classes.
>>>>>
>>>>> -Adrian
>>>>>
>>>>>
>>>>> --- On Wed, 6/9/10, Adrian Crum<[hidden email]>
>>>> wrote:
>>>>>> --- On Wed, 6/9/10, David E Jones
>>>>>> <[hidden email]>
>>>>>> wrote:
>>>>>>> On Jun 9, 2010, at 4:56 PM, Adrian Crum
>>>> wrote:
>>>>>>>
>>>>>>>> On 6/9/2010 3:44 PM, Adam Heath
>>> wrote:
>>>>>>>>> Adrian Crum wrote:
>>>>>>>>>> I remember when Javolution
>>> was
>>>> first
>>>>>> brought
>>>>>>> into the project. The
>>>>>>>>>> reason for adding it was
>>> better
>>>>>> performance. I
>>>>>>> was new to the project at
>>>>>>>>>> the time, so I just assumed
>>> that
>>>> was
>>>>>> true.
>>>>>>>>>>
>>>>>>>>>> Since then I have read many
>>> books
>>>> and
>>>>>> articles
>>>>>>> on Java, and now I'm not
>>>>>>>>>> sure that Javolution is
>>>> appropriate for
>>>>>> this
>>>>>>> project.
>>>>>>>>>
>>>>>>>>> I've also had doubts about
>>>>>>> FastMap(javolution).  It doesn't
>>>> implement
>>>>>>>>> ConcurrentMap; the putIfAbsent
>>> method
>>>> it
>>>>>> *does*
>>>>>>> implement is not
>>>>>>>>> completely defined.
>>>>>>>>>
>>>>>>>>> FastSet/FastMap don't have a
>>> defined
>>>>>> order.
>>>>>>> It appears to be linked,
>>>>>>>>> when no Comparator is used, but
>>> that
>>>> is not
>>>>>> well
>>>>>>> defined.
>>>>>>>>>
>>>>>>>>> javolution itself is supposed to
>>> be
>>>> defined
>>>>>> as
>>>>>>> being more consistent
>>>>>>>>> in memory usage and
>>> performance.
>>>> The
>>>>>> library
>>>>>>> says these are useful
>>>>>>>>> when the target platform is an
>>>> embedded
>>>>>>> environment.  However, ofbiz
>>>>>>>>> is not really an embedded-type
>>>>>> application.
>>>>>>> The extra overhead that
>>>>>>>>> javolution uses for maintain
>>> memory
>>>> block
>>>>>> areas
>>>>>>> makes it very hard for
>>>>>>>>> the jvm to do the new fancy
>>> escape
>>>> analysis.
>>>>>>>>> Lots of places in ofbiz use
>>>>>>> FastMap/List/Set.  They are not useful,
>>>>>>>>> however, in places that only get
>>>> populated
>>>>>> at
>>>>>>> startup, and never ever
>>>>>>>>> changed thereafter.  I've
>>> started
>>>> fixing
>>>>>> some
>>>>>>> of these use cases as I
>>>>>>>>> spot them.
>>>>>>>>
>>>>>>>> I've used arrays instead of Lists in
>>>> similar
>>>>>> cases. We
>>>>>>> really should have a discussion about
>>> this.
>>>> Using
>>>>>> Javolution
>>>>>>> by default in a shotgun attempt to
>>> improve
>>>> performance
>>>>>> is
>>>>>>> not a good strategy, in my opinion.
>>>>>>>
>>>>>>> I agree. If I understand correctly are
>>> you
>>>> saying that
>>>>>> the
>>>>>>> move away from javolution will NOT be
>>> done as
>>>> a
>>>>>> shotgun
>>>>>>> attempt to improve performance?
>>>>>>
>>>>>> Correct. Any changes that are made should be
>>> for a
>>>> good
>>>>>> reason.
>>>>>>
>>>>>> -Adrian
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>
>>>>>
>>>>>
>>>>
>>>>
>>>
>>>
>>>
>>>
>>
>>
>>
>
>

[Eilebrecht, Karl (Key-Work)]

Hi,

I've just read your conversation and I want to add my two cents:

When I started using Ofbiz I stumbled across the Javolution stuff inside and was really fascinated
because that time I was interested in object pooling during research for a chapter of my pattern book.
Javolution seems to be reliable and it is well documented.
I think the main power comes with the contexts concept.
Well, the contexts did not seem to be used in ofbiz that time, or have you started using
them in the meantime? I did not check the last built - but I don't think so.
Although, not using the context concept of Javolution one may lose some of the
advantages, Javolution still seems to provide clever implementations with a higher
performance resp. better memory/concurrency behavior than standard JDK classes under certain circumstances.
Maybe a big point for Javolution. But how long?

The JDK shows an interesting evolution over the last years. Every new JDK
has not only brought new features but also improvements to existing ones.
With every new JDK you'll receive these improvements (tested by millions of people)
for free mostly with full backward compatibility. Using a third-party library
any upgrade to the next version needs more attention, more discussion and more tests
( community(third party library) <= community(JDK) ;-) ).
Thus I came to the conclusion to not use Javolution for other projects than Ofbiz
when there is no explicit need to do so.

So, if you do not expect clear advantages from Javolution (other than "could be",
"theoretically" or "just a feeling") I would recommend to migrate back from Javolution classes to
standard JDK classes and - where appropriate - to use java.util.concurrent classes.

Regards
Karl

Karl Eilebrecht
Key-Work Consulting GmbH | Kriegsstr. 100 | 76133 Karlsruhe | Germany | www.key-work.de
Fon: [phone] | E-Mail: [hidden email] | Fax: [phone]

Key-Work Consulting GmbH Karlsruhe, HRB 108695, HRG Mannheim
Geschäftsführer: Andreas Stappert, Tobin Wotring
-----Ursprüngliche Nachricht-----
Von: Scott Gray [mailto:[hidden email]]
Gesendet: Donnerstag, 10. Juni 2010 10:33
An: [hidden email]
Betreff: Re: Discussion: When To Use Javolution (was: EntityCondition factory objects)

I will admit to thumping my chest and saying "ahhhhhhhh" at the same time.

But only after you guys mentioned it and only to bring back childhood memories.  Maybe I need some rest.

Regards
Scott

On 10/06/2010, at 8:23 PM, David E Jones wrote:

>
> At least I'm willing to admit it... :)
>
> -David
>
>
> On Jun 10, 2010, at 2:18 AM, Adrian Crum wrote:
>
>> My point was made since the beginning of the original thread. Javolution might not be the best choice in all situations. Let's discuss that.
>>
>> As far as I can tell, no one here is thumping their chest. Adam asked a legitimate question. I pointed to an informative article related to his question. We discussed the premise of that article. I thought it would be helpful for the community to discuss it further. Scott asked for more information and I offered it. If any chest thumping was done, it was in your last reply.
>>
>> -Adrian
>>
>> --- On Thu, 6/10/10, David E Jones <[hidden email]> wrote:
>>
>>> From: David E Jones <[hidden email]>
>>> Subject: Re: Discussion: When To Use Javolution (was: EntityCondition factory objects)
>>> To: [hidden email]
>>> Date: Thursday, June 10, 2010, 1:08 AM
>>>
>>> I'm sure there are good references around with a more
>>> complete list of differences. Be careful about pushing some
>>> differences and leaving out others, especially when bias is
>>> involved (ie arrays are better than linked lists). It may be
>>> that in some circumstances iterating is faster, but if so
>>> probably not by much (ie the difference between following a
>>> pointer versus incrementing an index).
>>>
>>> There are some things that linked lists do far better (like
>>> sorting, and most modifications actually), and if not
>>> intentionally optimized they can actually require more
>>> memory instead of less for smaller lists.
>>>
>>> To Scott's point... what (again) was the point of all of
>>> this? I guess it's always fun to thump one's chest and
>>> demonstrate knowledge of the concepts behind basic data
>>> structures, but most of this stuff fits into freshman
>>> computer science material, so even that isn't so much fun s
>>> not many people will be impressed.
>>>
>>> To your point Adrian, this stuff is definitely an issue,
>>> but unless you're looking at a specific piece of code and
>>> you actually profile to test alternatives it's really quite
>>> difficult to guess at what is better.
>>>
>>> That's part of the fun of profiling, the moment you find
>>> you were wrong is roughly the same moment when you find out
>>> what is right, even if it's often not what you expected.
>>> There are very few activities in life where those two events
>>> occur so close together... so it makes it kind of fun and
>>> only occasionally frustrating instead of the other way
>>> around... ;)
>>>
>>> -David
>>>
>>>
>>> On Jun 10, 2010, at 1:49 AM, Adrian Crum wrote:
>>>
>>>> Oops, I forgot to explain iteration differences.
>>> Iterating over an array is faster than traversing a
>>> doubly-linked list.
>>>>
>>>> -Adrian
>>>>
>>>> --- On Thu, 6/10/10, Adrian Crum <[hidden email]>
>>> wrote:
>>>>> I backed it up in an indirect way by
>>>>> mentioning the need to understand the Javolution
>>> library and
>>>>> its intended use. Go here to find out more:
>>>>>
>>>>> http://javolution.org/
>>>>>
>>>>> To summarize: Javolution was intended to be used
>>> in
>>>>> real-time systems where timing is critical. The
>>> library's
>>>>> goal is timing that is *consistent*, not
>>> necessarily fast.
>>>>>
>>>>> OFBiz is not a real-time application - it isn't
>>> being used
>>>>> to control robots or Mars rovers or anything
>>> timing-critical
>>>>> like that.
>>>>>
>>>>> You have to spend time on the Javolution site and
>>> poke
>>>>> around in their code a bit to understand the
>>>>> advantages/disadvantages. Adam has mentioned some
>>> of them in
>>>>> this thread and in previous threads.
>>>>>
>>>>> FastList implements a doubly-linked list. The list
>>> nodes
>>>>> are kept in an object pool. ArrayList wraps an
>>> array. If you
>>>>> think about it, the advantages/disadvantages will
>>> start to
>>>>> become evident. FastList will perform additions
>>> and removals
>>>>> more consistently than ArrayList because the
>>> change involves
>>>>> adding/removing a node. ArrayList resizes/copies
>>> the array
>>>>> it wraps, so the timing depends on the size of the
>>> array. A
>>>>> doubly-linked list will take more memory than
>>> ArrayList
>>>>> because the list elements are wrapped with nodes.
>>> An
>>>>> ArrayList will take more memory than the array it
>>> wraps
>>>>> because it contains additional bookkeeping data.
>>>>>
>>>>> -Adrian
>>>>>
>>>>>
>>>>> --- On Wed, 6/9/10, Scott Gray <[hidden email]>
>>>>> wrote:
>>>>>
>>>>>> From: Scott Gray <[hidden email]>
>>>>>> Subject: Re: Discussion: When To Use
>>> Javolution (was:
>>>>> EntityCondition factory objects)
>>>>>> To: [hidden email]
>>>>>> Date: Wednesday, June 9, 2010, 11:56 PM
>>>>>> Interesting post but what I'm not
>>>>>> hearing is any mention of specific downsides
>>> to using
>>>>>> javolution in place of the util classes even
>>> when the
>>>>> use
>>>>>> may not be taking advantage of any specific
>>>>> javolution
>>>>>> features.
>>>>>>
>>>>>> You mention this:
>>>>>>> There is no performance benefit to using
>>> FastList
>>>>> in
>>>>>> this scenario. An ArrayList will use less
>>> memory and
>>>>> will
>>>>>> perform faster than FastList - if its size is
>>>>> initialized to
>>>>>> the correct value. Better yet, if you know the
>>> number
>>>>> of
>>>>>> objects in advance, then just create an
>>> array.
>>>>>>
>>>>>> But you provide no evidence to back the
>>> statement
>>>>> up.
>>>>>> And a FastList can also be given an initial
>>> size.
>>>>>>
>>>>>> I'm disagreeing with what you're saying
>>> because I
>>>>> really
>>>>>> don't know much about it, but your post
>>> doesn't really
>>>>> do
>>>>>> much to increase my knowledge or give me any
>>> reason
>>>>> to
>>>>>> follow your advice.
>>>>>>
>>>>>> Regards
>>>>>> Scott
>>>>>>
>>>>>> HotWax Media
>>>>>> http://www.hotwaxmedia.com
>>>>>>
>>>>>> On 10/06/2010, at 6:25 PM, Adrian Crum wrote:
>>>>>>
>>>>>>> I'm continuing this discussion with a new
>>>>> subject
>>>>>> since the thread is starting to diverge from
>>> the
>>>>> original
>>>>>> subject.
>>>>>>>
>>>>>>> A lot of the current code uses Javolution
>>> classes
>>>>> in
>>>>>> many places for one common reason -
>>> copy-and-paste
>>>>>> development. If you don't understand the
>>> Javolution
>>>>> library
>>>>>> and its intended use and actual benefits then
>>> it's
>>>>> hard to
>>>>>> know when the classes should be used and when
>>> there
>>>>> might be
>>>>>> better alternatives.
>>>>>>>
>>>>>>> When I see class names like FastList and
>>> FastMap,
>>>>> I
>>>>>> assume using them will speed up code. Indeed,
>>> some JRE
>>>>> class
>>>>>> methods will execute faster using Javolution
>>> instead
>>>>> of JRE
>>>>>> classes, and those methods are well documented
>>> on the
>>>>>> Javolution website. If a bit of code doesn't
>>> use any
>>>>> of
>>>>>> those methods, then there will be no benefit
>>> to using
>>>>>> Javolution.
>>>>>>>
>>>>>>> Adam and I discussed earlier the use of
>>> object
>>>>> pools.
>>>>>> Object pools used to improve performance
>>> because they
>>>>> helped
>>>>>> cut down on garbage collection. Sun/Oracle
>>> recommends
>>>>>> getting rid of object pools when using the
>>> newer
>>>>> versions of
>>>>>> Java because the newer versions have improved
>>> garbage
>>>>>> collectors.
>>>>>>>
>>>>>>> If you do a Google search for "java
>>> performance
>>>>>> improvement" you'll get a lot of links to a
>>> lot of
>>>>> articles.
>>>>>> From my experience a lot of those ideas are
>>> based on
>>>>> some
>>>>>> special knowledge of how the JVM works and
>>> they "game
>>>>> the
>>>>>> system" to improve performance. As a result,
>>> some of
>>>>> those
>>>>>> optimizations depend on the JVM version and
>>> the
>>>>> platform it
>>>>>> runs on.
>>>>>>>
>>>>>>> My preference is to use efficient
>>> algorithms and
>>>>> well
>>>>>> structured code, and leave the performance
>>>>> optimizations to
>>>>>> the JVM. I can give an example that will be
>>> obvious
>>>>> to
>>>>>> everyone:
>>>>>>>
>>>>>>> Let's say a section of code builds a List
>>> of
>>>>> objects
>>>>>> and then iterates over the List. Once the List
>>> is
>>>>> created,
>>>>>> its contents don't change - there are no
>>> additions,
>>>>>> removals, inserts, etc. In addition, this List
>>> will be
>>>>> a
>>>>>> member of an object that is kept in a cache.
>>>>>>>
>>>>>>> There is no performance benefit to using
>>> FastList
>>>>> in
>>>>>> this scenario. An ArrayList will use less
>>> memory and
>>>>> will
>>>>>> perform faster than FastList - if its size is
>>>>> initialized to
>>>>>> the correct value. Better yet, if you know the
>>> number
>>>>> of
>>>>>> objects in advance, then just create an
>>> array.
>>>>>>>
>>>>>>> If an ArrayList is used, you can call the
>>>>> trimToSize
>>>>>> method after the List is filled to reduce the
>>> memory
>>>>> it
>>>>>> uses. Better yet, convert it to an array to
>>> reduce
>>>>> memory
>>>>>> use even more. A cached object that contains
>>> an array
>>>>>> instead of FastList will take less memory and
>>> perform
>>>>>> better.
>>>>>>>
>>>>>>> So, the main idea is to think about how
>>> the
>>>>> collection
>>>>>> is being used and then choose the best class
>>> for it.
>>>>> Don't
>>>>>> assume a Javolution class will always perform
>>> better.
>>>>>>>
>>>>>>> By the way, I'm not pointing any fingers
>>> or
>>>>> talking
>>>>>> down to anyone here. I've done the
>>> copy-and-paste
>>>>>> development myself. It's only recently that I
>>> started
>>>>> to
>>>>>> scrutinize my choice of classes.
>>>>>>>
>>>>>>> -Adrian
>>>>>>>
>>>>>>>
>>>>>>> --- On Wed, 6/9/10, Adrian Crum <[hidden email]>
>>>>>> wrote:
>>>>>>>> --- On Wed, 6/9/10, David E Jones
>>>>>>>> <[hidden email]>
>>>>>>>> wrote:
>>>>>>>>> On Jun 9, 2010, at 4:56 PM, Adrian
>>> Crum
>>>>>> wrote:
>>>>>>>>>
>>>>>>>>>> On 6/9/2010 3:44 PM, Adam
>>> Heath
>>>>> wrote:
>>>>>>>>>>> Adrian Crum wrote:
>>>>>>>>>>>> I remember when
>>> Javolution
>>>>> was
>>>>>> first
>>>>>>>> brought
>>>>>>>>> into the project. The
>>>>>>>>>>>> reason for adding it
>>> was
>>>>> better
>>>>>>>> performance. I
>>>>>>>>> was new to the project at
>>>>>>>>>>>> the time, so I just
>>> assumed
>>>>> that
>>>>>> was
>>>>>>>> true.
>>>>>>>>>>>>
>>>>>>>>>>>> Since then I have read
>>> many
>>>>> books
>>>>>> and
>>>>>>>> articles
>>>>>>>>> on Java, and now I'm not
>>>>>>>>>>>> sure that Javolution
>>> is
>>>>>> appropriate for
>>>>>>>> this
>>>>>>>>> project.
>>>>>>>>>>>
>>>>>>>>>>> I've also had doubts
>>> about
>>>>>>>>> FastMap(javolution).  It
>>> doesn't
>>>>>> implement
>>>>>>>>>>> ConcurrentMap; the
>>> putIfAbsent
>>>>> method
>>>>>> it
>>>>>>>> *does*
>>>>>>>>> implement is not
>>>>>>>>>>> completely defined.
>>>>>>>>>>>
>>>>>>>>>>> FastSet/FastMap don't have
>>> a
>>>>> defined
>>>>>>>> order.
>>>>>>>>> It appears to be linked,
>>>>>>>>>>> when no Comparator is
>>> used, but
>>>>> that
>>>>>> is not
>>>>>>>> well
>>>>>>>>> defined.
>>>>>>>>>>>
>>>>>>>>>>> javolution itself is
>>> supposed to
>>>>> be
>>>>>> defined
>>>>>>>> as
>>>>>>>>> being more consistent
>>>>>>>>>>> in memory usage and
>>>>> performance.
>>>>>> The
>>>>>>>> library
>>>>>>>>> says these are useful
>>>>>>>>>>> when the target platform
>>> is an
>>>>>> embedded
>>>>>>>>> environment.  However, ofbiz
>>>>>>>>>>> is not really an
>>> embedded-type
>>>>>>>> application.
>>>>>>>>> The extra overhead that
>>>>>>>>>>> javolution uses for
>>> maintain
>>>>> memory
>>>>>> block
>>>>>>>> areas
>>>>>>>>> makes it very hard for
>>>>>>>>>>> the jvm to do the new
>>> fancy
>>>>> escape
>>>>>> analysis.
>>>>>>>>>>> Lots of places in ofbiz
>>> use
>>>>>>>>> FastMap/List/Set.  They are
>>> not useful,
>>>>>>>>>>> however, in places that
>>> only get
>>>>>> populated
>>>>>>>> at
>>>>>>>>> startup, and never ever
>>>>>>>>>>> changed thereafter.
>>> I've
>>>>> started
>>>>>> fixing
>>>>>>>> some
>>>>>>>>> of these use cases as I
>>>>>>>>>>> spot them.
>>>>>>>>>>
>>>>>>>>>> I've used arrays instead of
>>> Lists in
>>>>>> similar
>>>>>>>> cases. We
>>>>>>>>> really should have a discussion
>>> about
>>>>> this.
>>>>>> Using
>>>>>>>> Javolution
>>>>>>>>> by default in a shotgun attempt
>>> to
>>>>> improve
>>>>>> performance
>>>>>>>> is
>>>>>>>>> not a good strategy, in my
>>> opinion.
>>>>>>>>>
>>>>>>>>> I agree. If I understand correctly
>>> are
>>>>> you
>>>>>> saying that
>>>>>>>> the
>>>>>>>>> move away from javolution will NOT
>>> be
>>>>> done as
>>>>>> a
>>>>>>>> shotgun
>>>>>>>>> attempt to improve performance?
>>>>>>>>
>>>>>>>> Correct. Any changes that are made
>>> should be
>>>>> for a
>>>>>> good
>>>>>>>> reason.
>>>>>>>>
>>>>>>>> -Adrian
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>
>>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>
>>>>
>>>>
>>>
>>>
>>
>>
>>
>

[David E. Jones-2]

Karl,

That's a good way to look at it. The JDK definitely progresses over time and more standard approaches may very well do as well or better.

If anyone wants to do some profiling to compare some alternatives to current framework code, that would be neat to see and would "seal the deal" as it were. Profiling is how we got into object pooling years ago, and it may be how we get out of object pooling too!

-David


On Jun 13, 2010, at 11:26 PM, Eilebrecht, Karl (Key-Work) wrote:

> Hi,
>
> I've just read your conversation and I want to add my two cents:
>
> When I started using Ofbiz I stumbled across the Javolution stuff inside and was really fascinated
> because that time I was interested in object pooling during research for a chapter of my pattern book.
> Javolution seems to be reliable and it is well documented.
> I think the main power comes with the contexts concept.
> Well, the contexts did not seem to be used in ofbiz that time, or have you started using
> them in the meantime? I did not check the last built - but I don't think so.
> Although, not using the context concept of Javolution one may lose some of the
> advantages, Javolution still seems to provide clever implementations with a higher
> performance resp. better memory/concurrency behavior than standard JDK classes under certain circumstances.
> Maybe a big point for Javolution. But how long?
>
> The JDK shows an interesting evolution over the last years. Every new JDK
> has not only brought new features but also improvements to existing ones.
> With every new JDK you'll receive these improvements (tested by millions of people)
> for free mostly with full backward compatibility. Using a third-party library
> any upgrade to the next version needs more attention, more discussion and more tests
> ( community(third party library) <= community(JDK) ;-) ).
> Thus I came to the conclusion to not use Javolution for other projects than Ofbiz
> when there is no explicit need to do so.
>
> So, if you do not expect clear advantages from Javolution (other than "could be",
> "theoretically" or "just a feeling") I would recommend to migrate back from Javolution classes to
> standard JDK classes and - where appropriate - to use java.util.concurrent classes.
>
> Regards
> Karl
>
> Karl Eilebrecht
> Key-Work Consulting GmbH | Kriegsstr. 100 | 76133 Karlsruhe | Germany | www.key-work.de
> Fon: [phone] | E-Mail: [hidden email] | Fax: [phone]
>
> Key-Work Consulting GmbH Karlsruhe, HRB 108695, HRG Mannheim
> Geschäftsführer: Andreas Stappert, Tobin Wotring
> -----Ursprüngliche Nachricht-----
> Von: Scott Gray [mailto:[hidden email]]
> Gesendet: Donnerstag, 10. Juni 2010 10:33
> An: [hidden email]
> Betreff: Re: Discussion: When To Use Javolution (was: EntityCondition factory objects)
>
> I will admit to thumping my chest and saying "ahhhhhhhh" at the same time.
>
> But only after you guys mentioned it and only to bring back childhood memories.  Maybe I need some rest.
>
> Regards
> Scott
>
> On 10/06/2010, at 8:23 PM, David E Jones wrote:
>
>>
>> At least I'm willing to admit it... :)
>>
>> -David
>>
>>
>> On Jun 10, 2010, at 2:18 AM, Adrian Crum wrote:
>>
>>> My point was made since the beginning of the original thread. Javolution might not be the best choice in all situations. Let's discuss that.
>>>
>>> As far as I can tell, no one here is thumping their chest. Adam asked a legitimate question. I pointed to an informative article related to his question. We discussed the premise of that article. I thought it would be helpful for the community to discuss it further. Scott asked for more information and I offered it. If any chest thumping was done, it was in your last reply.
>>>
>>> -Adrian
>>>
>>> --- On Thu, 6/10/10, David E Jones <[hidden email]> wrote:
>>>
>>>> From: David E Jones <[hidden email]>
>>>> Subject: Re: Discussion: When To Use Javolution (was: EntityCondition factory objects)
>>>> To: [hidden email]
>>>> Date: Thursday, June 10, 2010, 1:08 AM
>>>>
>>>> I'm sure there are good references around with a more
>>>> complete list of differences. Be careful about pushing some
>>>> differences and leaving out others, especially when bias is
>>>> involved (ie arrays are better than linked lists). It may be
>>>> that in some circumstances iterating is faster, but if so
>>>> probably not by much (ie the difference between following a
>>>> pointer versus incrementing an index).
>>>>
>>>> There are some things that linked lists do far better (like
>>>> sorting, and most modifications actually), and if not
>>>> intentionally optimized they can actually require more
>>>> memory instead of less for smaller lists.
>>>>
>>>> To Scott's point... what (again) was the point of all of
>>>> this? I guess it's always fun to thump one's chest and
>>>> demonstrate knowledge of the concepts behind basic data
>>>> structures, but most of this stuff fits into freshman
>>>> computer science material, so even that isn't so much fun s
>>>> not many people will be impressed.
>>>>
>>>> To your point Adrian, this stuff is definitely an issue,
>>>> but unless you're looking at a specific piece of code and
>>>> you actually profile to test alternatives it's really quite
>>>> difficult to guess at what is better.
>>>>
>>>> That's part of the fun of profiling, the moment you find
>>>> you were wrong is roughly the same moment when you find out
>>>> what is right, even if it's often not what you expected.
>>>> There are very few activities in life where those two events
>>>> occur so close together... so it makes it kind of fun and
>>>> only occasionally frustrating instead of the other way
>>>> around... ;)
>>>>
>>>> -David
>>>>
>>>>
>>>> On Jun 10, 2010, at 1:49 AM, Adrian Crum wrote:
>>>>
>>>>> Oops, I forgot to explain iteration differences.
>>>> Iterating over an array is faster than traversing a
>>>> doubly-linked list.
>>>>>
>>>>> -Adrian
>>>>>
>>>>> --- On Thu, 6/10/10, Adrian Crum <[hidden email]>
>>>> wrote:
>>>>>> I backed it up in an indirect way by
>>>>>> mentioning the need to understand the Javolution
>>>> library and
>>>>>> its intended use. Go here to find out more:
>>>>>>
>>>>>> http://javolution.org/
>>>>>>
>>>>>> To summarize: Javolution was intended to be used
>>>> in
>>>>>> real-time systems where timing is critical. The
>>>> library's
>>>>>> goal is timing that is *consistent*, not
>>>> necessarily fast.
>>>>>>
>>>>>> OFBiz is not a real-time application - it isn't
>>>> being used
>>>>>> to control robots or Mars rovers or anything
>>>> timing-critical
>>>>>> like that.
>>>>>>
>>>>>> You have to spend time on the Javolution site and
>>>> poke
>>>>>> around in their code a bit to understand the
>>>>>> advantages/disadvantages. Adam has mentioned some
>>>> of them in
>>>>>> this thread and in previous threads.
>>>>>>
>>>>>> FastList implements a doubly-linked list. The list
>>>> nodes
>>>>>> are kept in an object pool. ArrayList wraps an
>>>> array. If you
>>>>>> think about it, the advantages/disadvantages will
>>>> start to
>>>>>> become evident. FastList will perform additions
>>>> and removals
>>>>>> more consistently than ArrayList because the
>>>> change involves
>>>>>> adding/removing a node. ArrayList resizes/copies
>>>> the array
>>>>>> it wraps, so the timing depends on the size of the
>>>> array. A
>>>>>> doubly-linked list will take more memory than
>>>> ArrayList
>>>>>> because the list elements are wrapped with nodes.
>>>> An
>>>>>> ArrayList will take more memory than the array it
>>>> wraps
>>>>>> because it contains additional bookkeeping data.
>>>>>>
>>>>>> -Adrian
>>>>>>
>>>>>>
>>>>>> --- On Wed, 6/9/10, Scott Gray <[hidden email]>
>>>>>> wrote:
>>>>>>
>>>>>>> From: Scott Gray <[hidden email]>
>>>>>>> Subject: Re: Discussion: When To Use
>>>> Javolution (was:
>>>>>> EntityCondition factory objects)
>>>>>>> To: [hidden email]
>>>>>>> Date: Wednesday, June 9, 2010, 11:56 PM
>>>>>>> Interesting post but what I'm not
>>>>>>> hearing is any mention of specific downsides
>>>> to using
>>>>>>> javolution in place of the util classes even
>>>> when the
>>>>>> use
>>>>>>> may not be taking advantage of any specific
>>>>>> javolution
>>>>>>> features.
>>>>>>>
>>>>>>> You mention this:
>>>>>>>> There is no performance benefit to using
>>>> FastList
>>>>>> in
>>>>>>> this scenario. An ArrayList will use less
>>>> memory and
>>>>>> will
>>>>>>> perform faster than FastList - if its size is
>>>>>> initialized to
>>>>>>> the correct value. Better yet, if you know the
>>>> number
>>>>>> of
>>>>>>> objects in advance, then just create an
>>>> array.
>>>>>>>
>>>>>>> But you provide no evidence to back the
>>>> statement
>>>>>> up.
>>>>>>> And a FastList can also be given an initial
>>>> size.
>>>>>>>
>>>>>>> I'm disagreeing with what you're saying
>>>> because I
>>>>>> really
>>>>>>> don't know much about it, but your post
>>>> doesn't really
>>>>>> do
>>>>>>> much to increase my knowledge or give me any
>>>> reason
>>>>>> to
>>>>>>> follow your advice.
>>>>>>>
>>>>>>> Regards
>>>>>>> Scott
>>>>>>>
>>>>>>> HotWax Media
>>>>>>> http://www.hotwaxmedia.com
>>>>>>>
>>>>>>> On 10/06/2010, at 6:25 PM, Adrian Crum wrote:
>>>>>>>
>>>>>>>> I'm continuing this discussion with a new
>>>>>> subject
>>>>>>> since the thread is starting to diverge from
>>>> the
>>>>>> original
>>>>>>> subject.
>>>>>>>>
>>>>>>>> A lot of the current code uses Javolution
>>>> classes
>>>>>> in
>>>>>>> many places for one common reason -
>>>> copy-and-paste
>>>>>>> development. If you don't understand the
>>>> Javolution
>>>>>> library
>>>>>>> and its intended use and actual benefits then
>>>> it's
>>>>>> hard to
>>>>>>> know when the classes should be used and when
>>>> there
>>>>>> might be
>>>>>>> better alternatives.
>>>>>>>>
>>>>>>>> When I see class names like FastList and
>>>> FastMap,
>>>>>> I
>>>>>>> assume using them will speed up code. Indeed,
>>>> some JRE
>>>>>> class
>>>>>>> methods will execute faster using Javolution
>>>> instead
>>>>>> of JRE
>>>>>>> classes, and those methods are well documented
>>>> on the
>>>>>>> Javolution website. If a bit of code doesn't
>>>> use any
>>>>>> of
>>>>>>> those methods, then there will be no benefit
>>>> to using
>>>>>>> Javolution.
>>>>>>>>
>>>>>>>> Adam and I discussed earlier the use of
>>>> object
>>>>>> pools.
>>>>>>> Object pools used to improve performance
>>>> because they
>>>>>> helped
>>>>>>> cut down on garbage collection. Sun/Oracle
>>>> recommends
>>>>>>> getting rid of object pools when using the
>>>> newer
>>>>>> versions of
>>>>>>> Java because the newer versions have improved
>>>> garbage
>>>>>>> collectors.
>>>>>>>>
>>>>>>>> If you do a Google search for "java
>>>> performance
>>>>>>> improvement" you'll get a lot of links to a
>>>> lot of
>>>>>> articles.
>>>>>>> From my experience a lot of those ideas are
>>>> based on
>>>>>> some
>>>>>>> special knowledge of how the JVM works and
>>>> they "game
>>>>>> the
>>>>>>> system" to improve performance. As a result,
>>>> some of
>>>>>> those
>>>>>>> optimizations depend on the JVM version and
>>>> the
>>>>>> platform it
>>>>>>> runs on.
>>>>>>>>
>>>>>>>> My preference is to use efficient
>>>> algorithms and
>>>>>> well
>>>>>>> structured code, and leave the performance
>>>>>> optimizations to
>>>>>>> the JVM. I can give an example that will be
>>>> obvious
>>>>>> to
>>>>>>> everyone:
>>>>>>>>
>>>>>>>> Let's say a section of code builds a List
>>>> of
>>>>>> objects
>>>>>>> and then iterates over the List. Once the List
>>>> is
>>>>>> created,
>>>>>>> its contents don't change - there are no
>>>> additions,
>>>>>>> removals, inserts, etc. In addition, this List
>>>> will be
>>>>>> a
>>>>>>> member of an object that is kept in a cache.
>>>>>>>>
>>>>>>>> There is no performance benefit to using
>>>> FastList
>>>>>> in
>>>>>>> this scenario. An ArrayList will use less
>>>> memory and
>>>>>> will
>>>>>>> perform faster than FastList - if its size is
>>>>>> initialized to
>>>>>>> the correct value. Better yet, if you know the
>>>> number
>>>>>> of
>>>>>>> objects in advance, then just create an
>>>> array.
>>>>>>>>
>>>>>>>> If an ArrayList is used, you can call the
>>>>>> trimToSize
>>>>>>> method after the List is filled to reduce the
>>>> memory
>>>>>> it
>>>>>>> uses. Better yet, convert it to an array to
>>>> reduce
>>>>>> memory
>>>>>>> use even more. A cached object that contains
>>>> an array
>>>>>>> instead of FastList will take less memory and
>>>> perform
>>>>>>> better.
>>>>>>>>
>>>>>>>> So, the main idea is to think about how
>>>> the
>>>>>> collection
>>>>>>> is being used and then choose the best class
>>>> for it.
>>>>>> Don't
>>>>>>> assume a Javolution class will always perform
>>>> better.
>>>>>>>>
>>>>>>>> By the way, I'm not pointing any fingers
>>>> or
>>>>>> talking
>>>>>>> down to anyone here. I've done the
>>>> copy-and-paste
>>>>>>> development myself. It's only recently that I
>>>> started
>>>>>> to
>>>>>>> scrutinize my choice of classes.
>>>>>>>>
>>>>>>>> -Adrian
>>>>>>>>
>>>>>>>>
>>>>>>>> --- On Wed, 6/9/10, Adrian Crum <[hidden email]>
>>>>>>> wrote:
>>>>>>>>> --- On Wed, 6/9/10, David E Jones
>>>>>>>>> <[hidden email]>
>>>>>>>>> wrote:
>>>>>>>>>> On Jun 9, 2010, at 4:56 PM, Adrian
>>>> Crum
>>>>>>> wrote:
>>>>>>>>>>
>>>>>>>>>>> On 6/9/2010 3:44 PM, Adam
>>>> Heath
>>>>>> wrote:
>>>>>>>>>>>> Adrian Crum wrote:
>>>>>>>>>>>>> I remember when
>>>> Javolution
>>>>>> was
>>>>>>> first
>>>>>>>>> brought
>>>>>>>>>> into the project. The
>>>>>>>>>>>>> reason for adding it
>>>> was
>>>>>> better
>>>>>>>>> performance. I
>>>>>>>>>> was new to the project at
>>>>>>>>>>>>> the time, so I just
>>>> assumed
>>>>>> that
>>>>>>> was
>>>>>>>>> true.
>>>>>>>>>>>>>
>>>>>>>>>>>>> Since then I have read
>>>> many
>>>>>> books
>>>>>>> and
>>>>>>>>> articles
>>>>>>>>>> on Java, and now I'm not
>>>>>>>>>>>>> sure that Javolution
>>>> is
>>>>>>> appropriate for
>>>>>>>>> this
>>>>>>>>>> project.
>>>>>>>>>>>>
>>>>>>>>>>>> I've also had doubts
>>>> about
>>>>>>>>>> FastMap(javolution).  It
>>>> doesn't
>>>>>>> implement
>>>>>>>>>>>> ConcurrentMap; the
>>>> putIfAbsent
>>>>>> method
>>>>>>> it
>>>>>>>>> *does*
>>>>>>>>>> implement is not
>>>>>>>>>>>> completely defined.
>>>>>>>>>>>>
>>>>>>>>>>>> FastSet/FastMap don't have
>>>> a
>>>>>> defined
>>>>>>>>> order.
>>>>>>>>>> It appears to be linked,
>>>>>>>>>>>> when no Comparator is
>>>> used, but
>>>>>> that
>>>>>>> is not
>>>>>>>>> well
>>>>>>>>>> defined.
>>>>>>>>>>>>
>>>>>>>>>>>> javolution itself is
>>>> supposed to
>>>>>> be
>>>>>>> defined
>>>>>>>>> as
>>>>>>>>>> being more consistent
>>>>>>>>>>>> in memory usage and
>>>>>> performance.
>>>>>>> The
>>>>>>>>> library
>>>>>>>>>> says these are useful
>>>>>>>>>>>> when the target platform
>>>> is an
>>>>>>> embedded
>>>>>>>>>> environment.  However, ofbiz
>>>>>>>>>>>> is not really an
>>>> embedded-type
>>>>>>>>> application.
>>>>>>>>>> The extra overhead that
>>>>>>>>>>>> javolution uses for
>>>> maintain
>>>>>> memory
>>>>>>> block
>>>>>>>>> areas
>>>>>>>>>> makes it very hard for
>>>>>>>>>>>> the jvm to do the new
>>>> fancy
>>>>>> escape
>>>>>>> analysis.
>>>>>>>>>>>> Lots of places in ofbiz
>>>> use
>>>>>>>>>> FastMap/List/Set.  They are
>>>> not useful,
>>>>>>>>>>>> however, in places that
>>>> only get
>>>>>>> populated
>>>>>>>>> at
>>>>>>>>>> startup, and never ever
>>>>>>>>>>>> changed thereafter.
>>>> I've
>>>>>> started
>>>>>>> fixing
>>>>>>>>> some
>>>>>>>>>> of these use cases as I
>>>>>>>>>>>> spot them.
>>>>>>>>>>>
>>>>>>>>>>> I've used arrays instead of
>>>> Lists in
>>>>>>> similar
>>>>>>>>> cases. We
>>>>>>>>>> really should have a discussion
>>>> about
>>>>>> this.
>>>>>>> Using
>>>>>>>>> Javolution
>>>>>>>>>> by default in a shotgun attempt
>>>> to
>>>>>> improve
>>>>>>> performance
>>>>>>>>> is
>>>>>>>>>> not a good strategy, in my
>>>> opinion.
>>>>>>>>>>
>>>>>>>>>> I agree. If I understand correctly
>>>> are
>>>>>> you
>>>>>>> saying that
>>>>>>>>> the
>>>>>>>>>> move away from javolution will NOT
>>>> be
>>>>>> done as
>>>>>>> a
>>>>>>>>> shotgun
>>>>>>>>>> attempt to improve performance?
>>>>>>>>>
>>>>>>>>> Correct. Any changes that are made
>>>> should be
>>>>>> for a
>>>>>>> good
>>>>>>>>> reason.
>>>>>>>>>
>>>>>>>>> -Adrian
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>
>>>>>
>>>>>
>>>>
>>>>
>>>
>>>
>>>
>>
>
>