Is there any estimate what would be gained perf-wise by doing this optimization? > First, this obviously is more fragile than relying on names; if the order > changes but the bytecode is not re-enhanced, that could lead to very > subtle, nasty problems. Agreed, but to me it seems acceptable with such optimization having to be explicitly enabled and the docs of that setting describing this matter clearly. > The other issue is that this requires us to be able to consistently be able > to order the attributes. Maybe the enhancer could enhance entities with a (static) method returning the attribute order it works with, or maybe some separate contract for making this order available. Then at runtime this order could be fed to persisters et al. for enhanced entities. Not sure whether it's doable or how complex it'd be, just throwing out the idea.

--Gunnar 2015-11-11 21:37 GMT+01:00 Steve Ebersole <steve(a)hibernate.org&gt;: > As I work on HHH-10267, a thought that keeps coming up in my head is that > it would be great to avoid Map lookups in the enhancement and interception > code. > > As an example of what I mean, consider the reader for a String field named > `name` which roughly looks like: > > public String $$_hibernate_read_name() { > return (String) $$_hibernate_getInterceptor().readObject( this, "name", > this.name ); > } > > In the interception code we need to resolve the attribute name ("name" > above) to the pertinent information from the persister,etc. Typically this > is a Map lookup; sometimes it is a done by iterating a String[] of the > attribute names. > > Ultimately the information is taken from persister and friends, which means > that the information is generally already readily consumable via array > access once we have resolved the name to a proper index. Which got me > thinking it would be great if we could encode the attribute index into the > enhanced entity directly. Going back to the example about.. if we knew > that the "name" attribute was the 4th attribute (index=3) according to the > entity persister we could leverage that information for better performing > access to the attribute metadata in the enhanced code and interceptor: > > public String $$_hibernate_read_name() { > return (String) $$_hibernate_getInterceptor().readObject( this, 3, > this.name ); > } > > One gotcha - always has to be one devil right ;) Ok, 2 really... > > First, this obviously is more fragile than relying on names; if the order > changes but the bytecode is not re-enhanced, that could lead to very > subtle, nasty problems. > > The other issue is that this requires us to be able to consistently be able > to order the attributes. The Enhancer currently does not rely on the built > metadata (org.hibernate.mapping) at all; it parses the entity annotations > (completely annotation specific) on its own. Given the 2-phase break down > in JPA bootstrapping, having Enhancer leverage the built metadata is not > really going to be possible. Which is unfortunate, because doing so would > be nice for other reasons (like supporting XML mappings for enhancement as > well, etc). > > That's a lot of information, sorry about that :) > > But anyone have thoughts on that? > _______________________________________________ > hibernate-dev mailing list > hibernate-dev(a)lists.jboss.org > https://lists.jboss.org/mailman/listinfo/hibernate-dev

I have no estimate as to how much this would help. Many of the improvements coming from the performance work have been of the sort that is removing Map lookups; some of them across VERY small (and finite) sets of Map keys. My concern here is that the Map look up occurs any time an enhanced entity's getter or setter is called, which seems like a potentially bigger performance impact. I'm going to table this for now until the jandex-binding work. But as part of that work, I think it makes a ton of sense to make sure we develop a strategy for consistent ordering of processing attributes. On Thu, Nov 12, 2015 at 2:36 AM Gunnar Morling <gunnar(a)hibernate.org&gt; wrote: > Is there any estimate what would be gained perf-wise by doing this > optimization? > > > First, this obviously is more fragile than relying on names; if the > order > > changes but the bytecode is not re-enhanced, that could lead to very > > subtle, nasty problems. > > Agreed, but to me it seems acceptable with such optimization having to > be explicitly enabled and the docs of that setting describing this > matter clearly. > > > The other issue is that this requires us to be able to consistently be > able > > to order the attributes. > > Maybe the enhancer could enhance entities with a (static) method > returning the attribute order it works with, or maybe some separate > contract for making this order available. Then at runtime this order > could be fed to persisters et al. for enhanced entities. > > Not sure whether it's doable or how complex it'd be, just throwing out > the idea. > > --Gunnar > > > 2015-11-11 21:37 GMT+01:00 Steve Ebersole <steve(a)hibernate.org&gt;: > > As I work on HHH-10267, a thought that keeps coming up in my head is > that > > it would be great to avoid Map lookups in the enhancement and > interception > > code. > > > > As an example of what I mean, consider the reader for a String field > named > > `name` which roughly looks like: > > > > public String $$_hibernate_read_name() { > > return (String) $$_hibernate_getInterceptor().readObject( this, > "name", > > this.name ); > > } > > > > In the interception code we need to resolve the attribute name ("name" > > above) to the pertinent information from the persister,etc. Typically > this > > is a Map lookup; sometimes it is a done by iterating a String[] of the > > attribute names. > > > > Ultimately the information is taken from persister and friends, which > means > > that the information is generally already readily consumable via array > > access once we have resolved the name to a proper index. Which got me > > thinking it would be great if we could encode the attribute index into > the > > enhanced entity directly. Going back to the example about.. if we knew > > that the "name" attribute was the 4th attribute (index=3) according to > the > > entity persister we could leverage that information for better > performing > > access to the attribute metadata in the enhanced code and interceptor: > > > > public String $$_hibernate_read_name() { > > return (String) $$_hibernate_getInterceptor().readObject( this, 3, > > this.name ); > > } > > > > One gotcha - always has to be one devil right ;) Ok, 2 really... > > > > First, this obviously is more fragile than relying on names; if the > order > > changes but the bytecode is not re-enhanced, that could lead to very > > subtle, nasty problems. > > > > The other issue is that this requires us to be able to consistently be > able > > to order the attributes. The Enhancer currently does not rely on the > built > > metadata (org.hibernate.mapping) at all; it parses the entity > annotations > > (completely annotation specific) on its own. Given the 2-phase break > down > > in JPA bootstrapping, having Enhancer leverage the built metadata is not > > really going to be possible. Which is unfortunate, because doing so > would > > be nice for other reasons (like supporting XML mappings for enhancement > as > > well, etc). > > > > That's a lot of information, sorry about that :) > > > > But anyone have thoughts on that? > > _______________________________________________ > > hibernate-dev mailing list > > hibernate-dev(a)lists.jboss.org > > https://lists.jboss.org/mailman/listinfo/hibernate-dev >

It would be a one-time effort during persister initialisation; At that time a look-up would happen in order to seed persisters with attributes in the order as determined by the enhancer. Then at runtime, upon getter/setter invocation, the index values passed from the enhanced code would be used as is for array index access in persisters. 2015-11-12 15:30 GMT+01:00 Steve Ebersole <steve(a)hibernate.org&gt;: > But I think that just redefines the same problem. Just that now instead of > String->Integer we need some Integer->Integer resolution. Not sure that > really gains us anything. > > On Thu, Nov 12, 2015 at 8:29 AM Steve Ebersole <steve(a)hibernate.org&gt; wrote: >> >> I have no estimate as to how much this would help. Many of the >> improvements coming from the performance work have been of the sort that is >> removing Map lookups; some of them across VERY small (and finite) sets of >> Map keys. My concern here is that the Map look up occurs any time an >> enhanced entity's getter or setter is called, which seems like a potentially >> bigger performance impact. >> >> I'm going to table this for now until the jandex-binding work. But as >> part of that work, I think it makes a ton of sense to make sure we develop a >> strategy for consistent ordering of processing attributes. >> >> On Thu, Nov 12, 2015 at 2:36 AM Gunnar Morling <gunnar(a)hibernate.org&gt; >> wrote: >>> >>> Is there any estimate what would be gained perf-wise by doing this >>> optimization? >>> >>> > First, this obviously is more fragile than relying on names; if the >>> > order >>> > changes but the bytecode is not re-enhanced, that could lead to very >>> > subtle, nasty problems. >>> >>> Agreed, but to me it seems acceptable with such optimization having to >>> be explicitly enabled and the docs of that setting describing this >>> matter clearly. >>> >>> > The other issue is that this requires us to be able to consistently be >>> > able >>> > to order the attributes. >>> >>> Maybe the enhancer could enhance entities with a (static) method >>> returning the attribute order it works with, or maybe some separate >>> contract for making this order available. Then at runtime this order >>> could be fed to persisters et al. for enhanced entities. >>> >>> Not sure whether it's doable or how complex it'd be, just throwing out >>> the idea. >>> >>> --Gunnar >>> >>> >>> 2015-11-11 21:37 GMT+01:00 Steve Ebersole <steve(a)hibernate.org&gt;: >>> > As I work on HHH-10267, a thought that keeps coming up in my head is >>> > that >>> > it would be great to avoid Map lookups in the enhancement and >>> > interception >>> > code. >>> > >>> > As an example of what I mean, consider the reader for a String field >>> > named >>> > `name` which roughly looks like: >>> > >>> > public String $$_hibernate_read_name() { >>> > return (String) $$_hibernate_getInterceptor().readObject( this, >>> > "name", >>> > this.name ); >>> > } >>> > >>> > In the interception code we need to resolve the attribute name ("name" >>> > above) to the pertinent information from the persister,etc. Typically >>> > this >>> > is a Map lookup; sometimes it is a done by iterating a String[] of the >>> > attribute names. >>> > >>> > Ultimately the information is taken from persister and friends, which >>> > means >>> > that the information is generally already readily consumable via array >>> > access once we have resolved the name to a proper index. Which got me >>> > thinking it would be great if we could encode the attribute index into >>> > the >>> > enhanced entity directly. Going back to the example about.. if we knew >>> > that the "name" attribute was the 4th attribute (index=3) according to >>> > the >>> > entity persister we could leverage that information for better >>> > performing >>> > access to the attribute metadata in the enhanced code and interceptor: >>> > >>> > public String $$_hibernate_read_name() { >>> > return (String) $$_hibernate_getInterceptor().readObject( this, 3, >>> > this.name ); >>> > } >>> > >>> > One gotcha - always has to be one devil right ;) Ok, 2 really... >>> > >>> > First, this obviously is more fragile than relying on names; if the >>> > order >>> > changes but the bytecode is not re-enhanced, that could lead to very >>> > subtle, nasty problems. >>> > >>> > The other issue is that this requires us to be able to consistently be >>> > able >>> > to order the attributes. The Enhancer currently does not rely on the >>> > built >>> > metadata (org.hibernate.mapping) at all; it parses the entity >>> > annotations >>> > (completely annotation specific) on its own. Given the 2-phase break >>> > down >>> > in JPA bootstrapping, having Enhancer leverage the built metadata is >>> > not >>> > really going to be possible. Which is unfortunate, because doing so >>> > would >>> > be nice for other reasons (like supporting XML mappings for enhancement >>> > as >>> > well, etc). >>> > >>> > That's a lot of information, sorry about that :) >>> > >>> > But anyone have thoughts on that? >>> > _______________________________________________ >>> > hibernate-dev mailing list >>> > hibernate-dev(a)lists.jboss.org >>> > https://lists.jboss.org/mailman/listinfo/hibernate-dev

> You want us to delay enhancement until after the persisters are built. No, I mean to let enhancement define the attribute ordering and initialize persisters with that previously defined order. > What I suggest longer term is a slight variation... Yes, that sounds nice. 2015-11-12 16:07 GMT+01:00 Steve Ebersole <steve(a)hibernate.org&gt;: > But see that is exactly the problem. That cannot work. You want us to > delay enhancement until after the persisters are built. But building the > persisters requires access to the Class. But by that time since we have the > Class reference we can no longer enhance it. It's a chicken-egg problem. > > What I suggest longer term is a slight variation, where we drive the > "indexing" based on the mapping model. Actually that also will not work as > the code is today. Really what I'd like to do is to leverage the > jandex-binding work. Specifically there we have a Jandex-driven pre-parsing > of the domain model (including XML augmentation). That model would be > perfect for this. > > On Thu, Nov 12, 2015 at 9:00 AM Gunnar Morling <gunnar(a)hibernate.org&gt; wrote: >> >> It would be a one-time effort during persister initialisation; At that >> time a look-up would happen in order to seed persisters with >> attributes in the order as determined by the enhancer. Then at >> runtime, upon getter/setter invocation, the index values passed from >> the enhanced code would be used as is for array index access in >> persisters. >> >> 2015-11-12 15:30 GMT+01:00 Steve Ebersole <steve(a)hibernate.org&gt;: >> > But I think that just redefines the same problem. Just that now instead >> > of >> > String->Integer we need some Integer->Integer resolution. Not sure that >> > really gains us anything. >> > >> > On Thu, Nov 12, 2015 at 8:29 AM Steve Ebersole <steve(a)hibernate.org&gt; >> > wrote: >> >> >> >> I have no estimate as to how much this would help. Many of the >> >> improvements coming from the performance work have been of the sort >> >> that is >> >> removing Map lookups; some of them across VERY small (and finite) sets >> >> of >> >> Map keys. My concern here is that the Map look up occurs any time an >> >> enhanced entity's getter or setter is called, which seems like a >> >> potentially >> >> bigger performance impact. >> >> >> >> I'm going to table this for now until the jandex-binding work. But as >> >> part of that work, I think it makes a ton of sense to make sure we >> >> develop a >> >> strategy for consistent ordering of processing attributes. >> >> >> >> On Thu, Nov 12, 2015 at 2:36 AM Gunnar Morling <gunnar(a)hibernate.org&gt; >> >> wrote: >> >>> >> >>> Is there any estimate what would be gained perf-wise by doing this >> >>> optimization? >> >>> >> >>> > First, this obviously is more fragile than relying on names; if the >> >>> > order >> >>> > changes but the bytecode is not re-enhanced, that could lead to very >> >>> > subtle, nasty problems. >> >>> >> >>> Agreed, but to me it seems acceptable with such optimization having to >> >>> be explicitly enabled and the docs of that setting describing this >> >>> matter clearly. >> >>> >> >>> > The other issue is that this requires us to be able to consistently >> >>> > be >> >>> > able >> >>> > to order the attributes. >> >>> >> >>> Maybe the enhancer could enhance entities with a (static) method >> >>> returning the attribute order it works with, or maybe some separate >> >>> contract for making this order available. Then at runtime this order >> >>> could be fed to persisters et al. for enhanced entities. >> >>> >> >>> Not sure whether it's doable or how complex it'd be, just throwing out >> >>> the idea. >> >>> >> >>> --Gunnar >> >>> >> >>> >> >>> 2015-11-11 21:37 GMT+01:00 Steve Ebersole <steve(a)hibernate.org&gt;: >> >>> > As I work on HHH-10267, a thought that keeps coming up in my head is >> >>> > that >> >>> > it would be great to avoid Map lookups in the enhancement and >> >>> > interception >> >>> > code. >> >>> > >> >>> > As an example of what I mean, consider the reader for a String field >> >>> > named >> >>> > `name` which roughly looks like: >> >>> > >> >>> > public String $$_hibernate_read_name() { >> >>> > return (String) $$_hibernate_getInterceptor().readObject( this, >> >>> > "name", >> >>> > this.name ); >> >>> > } >> >>> > >> >>> > In the interception code we need to resolve the attribute name >> >>> > ("name" >> >>> > above) to the pertinent information from the persister,etc. >> >>> > Typically >> >>> > this >> >>> > is a Map lookup; sometimes it is a done by iterating a String[] of >> >>> > the >> >>> > attribute names. >> >>> > >> >>> > Ultimately the information is taken from persister and friends, >> >>> > which >> >>> > means >> >>> > that the information is generally already readily consumable via >> >>> > array >> >>> > access once we have resolved the name to a proper index. Which got >> >>> > me >> >>> > thinking it would be great if we could encode the attribute index >> >>> > into >> >>> > the >> >>> > enhanced entity directly. Going back to the example about.. if we >> >>> > knew >> >>> > that the "name" attribute was the 4th attribute (index=3) according >> >>> > to >> >>> > the >> >>> > entity persister we could leverage that information for better >> >>> > performing >> >>> > access to the attribute metadata in the enhanced code and >> >>> > interceptor: >> >>> > >> >>> > public String $$_hibernate_read_name() { >> >>> > return (String) $$_hibernate_getInterceptor().readObject( this, >> >>> > 3, >> >>> > this.name ); >> >>> > } >> >>> > >> >>> > One gotcha - always has to be one devil right ;) Ok, 2 really... >> >>> > >> >>> > First, this obviously is more fragile than relying on names; if the >> >>> > order >> >>> > changes but the bytecode is not re-enhanced, that could lead to very >> >>> > subtle, nasty problems. >> >>> > >> >>> > The other issue is that this requires us to be able to consistently >> >>> > be >> >>> > able >> >>> > to order the attributes. The Enhancer currently does not rely on >> >>> > the >> >>> > built >> >>> > metadata (org.hibernate.mapping) at all; it parses the entity >> >>> > annotations >> >>> > (completely annotation specific) on its own. Given the 2-phase >> >>> > break >> >>> > down >> >>> > in JPA bootstrapping, having Enhancer leverage the built metadata is >> >>> > not >> >>> > really going to be possible. Which is unfortunate, because doing so >> >>> > would >> >>> > be nice for other reasons (like supporting XML mappings for >> >>> > enhancement >> >>> > as >> >>> > well, etc). >> >>> > >> >>> > That's a lot of information, sorry about that :) >> >>> > >> >>> > But anyone have thoughts on that? >> >>> > _______________________________________________ >> >>> > hibernate-dev mailing list >> >>> > hibernate-dev(a)lists.jboss.org >> >>> > https://lists.jboss.org/mailman/listinfo/hibernate-dev _______________________________________________ hibernate-dev mailing list hibernate-dev(a)lists.jboss.org https://lists.jboss.org/mailman/listinfo/hibernate-dev