Hello
On our current project we have a fairly large database model mapped
thru Hibernate JPA annotations: around 150 entities.
Those JPA entities have a lot of @ManyToOne, @OneToMany, @ManyToMany
inter relations.
On the server side Hibernate lazy loading is active and managed
correctly so that no extra unneeded collections are fetched to the
client.
I’m using Gilead in stateless mode with all JPA entities extending
java.io.Serializable and net.sf.gilead.pojo.gwt.LightEntity
So back to the client side, I created a simple RPC Service
@RemoteServiceRelativePath("country.rpc")
public interface CountryService extends RemoteService
{
Country findCountry(String countryId);
}
public interface CountryServiceAsync
{
void findCountry(String countryId, AsyncCallback<Country>
callback);
}
The Country type has several Collection fields whose type have as well
their own relations. But, again, thanks to lazy loading, those
collections are empty.
Problem arise when I try to create the service using Development Mode
(Run As Web Application in Eclipse)
CountryServiceAsync countryService = GWT.create(CountryService.class);
GWT.create()'s goal is to create a client proxy for the remote
service's server side implementation.
Extract from the "Development Mode" console:
12:30:18.664 [DEBUG] [project] Invoking
com.google.gwt.dev.javac.standardgeneratorcont...@904576
12:30:18.664 [DEBUG] [project] Generating client proxy for remote
service interface
'com.company.project.client.services.CountryServiceClient'
12:30:18.664 [DEBUG] [project] Analyzing
'com.company.project.client.services.CountryServiceClient' for
serializable types
12:30:18.664 [DEBUG] [project] Analyzing methods:
12:30:18.664 [DEBUG] [project] public abstract
com.company.project.server.dom.Country findCountry(java.lang.String
countryId)
12:30:18.664 [DEBUG] [project] Return type:
com.company.project.server.dom.Country
12:30:20.648 [DEBUG] [project] com.company.project.server.dom.Country
12:30:20.648 [DEBUG] [project] Finding possibly instantiable subtypes
.
.
.
Then a huge tree a dependent subtypes that qualify for serialization
is built.
At this point, GWT.create method returns after around 5 minutes !
Nothing mentions in the documentation that Serialization performance
depends on the number of imports of a types, including imported types
of its children:
http://code.google.com/webtoolkit/doc/latest/DevGuideServerCommunication.html#DevGuideMakingACall
If you read this link:
http://sinnema313.wordpress.com/2008/11/16/performance-tuning-a-gwt-application/
It mentions that "Serialization is slow: (...) Serialization
performance appears to be proportional to the number of objects, not
just to their total size."
I see 2 possible solutions:
- Cache serializable types (gwt.rpc file) and load them with the
module, but I don’t know if it's feasible with current GWT API
- Use DTOs and Dozer to drastically denormalize our model object and
limit the number of inter relations between types.
Did any of you already faced this performance problem ?
Thanks
Fred
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