PackageNotFoundException is instanciated a lot and quite costly

[pcdavid]

In org.eclipse.sirius.emfjson.utils.GsonEObjectDeserializer.deserializeMultipleNonContainmentEReference (among others) we try to resolve the resource part of a reference URI as an EPackage using getPackageForURI(String uriString).

This works for the case where the reference URI is of the form e.g. http://www.eclipse.org/emf/2002/Ecore#//EBoolean, but will fail in most concrete cases where the reference URI will be something like 52317c1f-0516-48b4-bad4-15a3a07aebe9#//path/to/some/element.1. In such a case getPackageForURI keeps track of the error with:

this.helper.getResource().getErrors().add(new PackageNotFoundException(uriString, this.helper.getResourceURI().toString()));

Unfortunately, the error type used, PackageNotFoundException is an actual Java exception, which is very costly to create (because of fillStackTrace). I'm not sure why this Resource.Diagnostic (along with all the other JsonException subtypes) are exceptions, but just commenting out this line to avoid creating thousands of exceptions when loading a medium-sized model give a significant performance boost:

Before (master, emf-json 2.3.9/master):

• EditingContext loaded in 2750ms
• EditingContext loaded in 1989ms
• EditingContext loaded in 2179ms
• EditingContext loaded in 2032ms
• EditingContext loaded in 2210ms
• EditingContext loaded in 2303ms
• EditingContext loaded in 1892ms
• Average: 2193ms

After (commented this.helper.getResource().getErrors().add(new PackageNotFoundException()))

• EditingContext loaded in 1746ms
• EditingContext loaded in 1674ms
• EditingContext loaded in 1663ms
• EditingContext loaded in 1686ms
• EditingContext loaded in 1697ms
• EditingContext loaded in 1682ms
• Average: 1691ms

Simply commenting out the code is probably too much, but replacing an exception with a plain Resource.Diagnostic object should get us most of the gain (I need to confirm).

[pcdavid]

Here's a measure of the time just building the PacakgeNotFoundException instances when loading the "Sirius Web" Papaya example:

[pcdavid]

After switching to a plain class implementing EMF's Resource.Diagnostic directly, it's still invoked 20k times but but now accounts for ~1ms in total:

(I had to switch to YourKit's tracing mode, as in sampling mode it's not even measurable).