Hi Sergey, again,
I am afraid that we are in the middle of some big misunderstanding, me being
the one who has started it. Unfortunately, it turned out that I didn't quite
realize, that javax.ws.rs.core.Application#getClasses() returns a
non-modifiable collection (Collections.emptySet()), and in my exception mapper
I used:
public Set<Class<?>> getClasses() {
// TODO Auto-generated method stub
Set<Class<?>> classes = super.getClasses();
classes.add(SimpleApplicationExceptionMapper.class);
return classes;
}
which probably leads to an java.lang.UnsupportedOperationException at runtime,
and thus to some work flow/behavior that I am not aware of. This made mu
numbers faster, but obviously the scenario is broken, so the results are
irrelevant.
Next, I took a look at some examples, like
this<http://grepcode.com/file/repo1.maven.org/maven2/com.sun.jersey.samples/jersey-ejb/1.11/com/sun/jersey/samples/jersey_ejb/resources/MyApplication.java?av=f>
one, and modified my code accordingly. Unfortunately, I got the same results:
0.500 seconds for the 404 cases. I am not even sure that my exception mapper
was really used, since when I inserted some dumps, and even when I threw some
exceptions in my toResponse() method, I didn't see them nowhere.
Next, I made a step further, and patched the WebApplicationExceptionMapper that
comes with CXF to look like this:
public class WebApplicationExceptionMapper implements
ExceptionMapper<WebApplicationException> {
public Response toResponse(WebApplicationException ex) {
return ex.getResponse();
}
}
I made sure that it was really used. Unfortunately, I got the same results:
roundtrip time was again ~0.500 seconds.
I am really not sure whether the CXF-4121 bug makes sense any more. Problem is
still here ;(
Kindest Regards,
Krum.
-----Original Message-----
From: Bakalsky, Krum
Sent: Wednesday, February 22, 2012 11:35 AM
To: '[email protected]'
Subject: RE: REST performance discrepancies between CXF and Jersey
Hi Sergey,
I have just made a test run with the modified WebApplicationException mapper
that you have given a link to below, and it works fine: it also shows 10 times
decrease of roundtrip duration as well. So, it seems that you have really
optimized it pretty good already.
Sure, I don't have any particular objections or concerns as to how to approach
the change that we are talking about. I'd guess that as long as the application
has a way to configure its own exception mapper (which is already the case) so
that 404 overhead is gone for it, things are fine. I wouldn't know for those
implications and complications that adding a property could lead to. Thanks for
sharing.
We haven't identified particular 'slow' code fragments, other than the 404
processing. If we do, we will sure let you know. (or if you want, you could
share your suspicions and give us some hint of where to take a look at ?)
Kindest Regards,
Krum.
-----Original Message-----
From: Sergey Beryozkin [mailto:[email protected]]
Sent: Tuesday, February 21, 2012 8:34 PM
To: [email protected]
Subject: Re: REST performance discrepancies between CXF and Jersey
Hi Krum,
On 20/02/12 16:47, Bakalsky, Krum wrote:
> Hi,
>
> Yes, thanks for the comments, they sound very logical to explaining the
> numbers from all the variants we tested.
> Didn't know that the default exception mapper was developed as a result of a
> user demand as well.
>
> For the record: how could I disable it ? I am registering the Simple mapper
> within the returned set of the Application#getClasses() method call - so
> maybe I should remove it there, i.e. from the super.getClasses() list, or it
> is in a different manner ?
>
> Yes, I think that a servlet context parameter would be the most flexible and
> elegant solution, for configuring the desired behavior for
> non-200/exceptional cases.
>
I've spent some today on optimizing a couple of things,
see the updated default WebApplicationException mapper:
http://svn.apache.org/repos/asf/cxf/trunk/rt/frontend/jaxrs/src/main/java/org/apache/cxf/jaxrs/impl/WebApplicationExceptionMapper.java
I think it's more effective now, yes still it is configurable and able
to interact with CXF FaultLoggers and optionally fine-log the exception
message.
I was thinking yesterday of adding a property to get this default mapper
ignored. I'm not sure now it's worth going this route.
One way to 'disable' it is to offer a custom WebApplicationException
mapper, something which we've explored. Another one - is to add this
would be property but I've realized that it's not that good for CXF
after all: this would require the CXF servlet to process unmapped
WebApplicationExceptions to be compliant and this would effectively mean
repeating at the servlet level what is done at the CXF chain level but
with limitations, ex, the Response produced by the mapper would still be
routed through the out filters and indeed the optional CXF out faulty
interceptors which can be handy. Say we can have an out filter which
time-stamps all the responses - this would be ignored at the servlet
level and would effectively have to be duplicated if needed...
The other thing is that CXFNonSpringJaxrsServlet and servlet filters
will not be necessarily installed in some OSGI containers by default.
So it appears to be the best way is to optimize the default mapper which
I hope I did, and it would be always possible to offer custom mappers
instead on per-Application basis.
Let me know please if you have any concerns with the above,
In meantime I also updated some code on the in chain to optimize the way
the HTTP path to match is calculated - it may well save us few
milliseconds :-)
If you can share some more results from your tests which point to few
unoptimized code spots then it would be good; we are going to review few
code paths anyway,
Thanks, Sergey
>
> Kindest Regards and many thanks again,
> Krum.
>
> -----Original Message-----
> From: Sergey Beryozkin [mailto:[email protected]]
> Sent: Monday, February 20, 2012 5:49 PM
> To: [email protected]
> Subject: Re: REST performance discrepancies between CXF and Jersey
>
> Hi,
> On 20/02/12 15:28, Sergey Beryozkin wrote:
>> Hi Krum
>> On 20/02/12 15:05, Bakalsky, Krum wrote:
>>> Hi Sergey,
>>>
>>> Wow! I tested your idea and it produced dramatically better results!
>>> The roundtrip time for 404 requests decreased by a factor of 10 (from
>>> 0.500 seconds down to 0.030 seconds). That is a huge success for our
>>> investigation, and I believe that our observation is really true that
>>> the overhead is spent in the error handling code. Just out of
>>> curiosity: with the same SimpleApplicationMapper:
>>>
>> Thanks for the confirmation, so we've identified the spot where the
>> problem is :-)
>>
>>> public class SimpleApplicationExceptionMapper implements
>>> ExceptionMapper<WebApplicationException> {
>>>
>>> @Override
>>> public Response toResponse(WebApplicationException exception) {
>>> return Response.status(404).build();
>>> }
>>>
>>> }
>>>
>>> Jersey behaved very similarly to CXF in terms of roundtrip time.
>>>
>>>
>>> However, without this class, Jersey performed even faster - most of
>>> the times were 10 times faster, i.e. around 0.003 seconds, while in
>>> the CXF case ... you already know it :) - 0.500 seconds
>>>
>
> Forgot to comment to this one... I think the fact that both frameworks
> show approximately the same time with SimpleApplicationExceptionMapper
> in place and that Jersey scales really well without it is that Jersey
> basically either writes to HTTP out stream or propagates the exception
> up to the ServletException filter immediately if no custom mapper is
> available.
> In case of CXF the immediate propagation will also happen if no custom
> mapper is available. The reason the default WebApplicationException
> Mapper was installed was to do with the fact that few users were not
> quite happy with having to write their custom mappers in order to report
> differently to the exceptions generated at the runtime level or some of
> the providers' level or indeed having to write a filter catching the
> escaped exceptions there...
>
> What I might need to do additionally is to introduce a contextual
> property that will tell the runtime to ignore even the default
> WebApplicationException mapper, for example, when the user wishes to
> get all the exceptions propagated to the filter level, to simplify the
> performance data comparison, etc
>
> Cheers, Sergey
>
>>>
>>> Thank a lot for your idea and suggestion! It definitely shed light on
>>> where the discrepancies come from.
>>>
>> I've opened
>> https://issues.apache.org/jira/browse/CXF-4121
>>
>> I suspect now that it is the specific lines which get the basic warning
>> message from the resource bundle are main 'culprits', I guess I will
>> just have an internal final static String - will need to experiment a
>> bit...It is good even the default providers can be customized/replaced,
>> but I'll look into trying to make the default exception mapper
>> performing a bit better :-)
>>
>> Thanks, Sergey
>>>
>>> Kindest Regards,
>>> Krum.
>>>
>>> -----Original Message-----
>>> From: Sergey Beryozkin [mailto:[email protected]]
>>> Sent: Friday, February 17, 2012 6:14 PM
>>> To: [email protected]
>>> Subject: Re: REST performance discrepancies between CXF and Jersey
>>>
>>> Hi Krum,
>>> On 17/02/12 15:26, Bakalsky, Krum wrote:
>>>> Hi to all Apache CXF users!,
>>>>
>>>> I would kindly like to bring to your attention a particular problem
>>>> that we are currently being stuck into. We are experimenting with a
>>>> simple web application, which exposes its functionality via REST. We
>>>> are using JAX-RS/JSON, no SOAP, no JAX-WS. We deploy our application
>>>> on top of Tomcat 7, and test both against CXF 2.5.2 and Jersey as
>>>> REST frameworks.
>>>>
>>>> For calculating our performance measurements, we simply execute REST
>>>> requests, and in the client we measure the time that the roundtrip
>>>> takes. Apart from that, on the server side, we measure as well the
>>>> time that our REST resource consumes, i.e. the method call time. In
>>>> summary, we have some huge differences between CXF and Jersey - in
>>>> favor of Jersey being much faster - in the cases where we test
>>>> against non-existing resources. In all other cases, the numbers we
>>>> got were really very close for the two REST frameworks.
>>>>
>>>> But when testing against non-existing REST paths, the roundtrip time
>>>> in CXF case is approximately 0.5 seconds, while in the case of Jersey
>>>> it is 0.01 seconds. We think that this is quite strange, and probably
>>>> we are not using CXF in its proper configuration. Could you please
>>>> give us some hints ? Maybe we have to tune and tweak it a little bit,
>>>> so that we get the best out of it.
>>>>
>>>> The server side time, in the case of CXF, is rather small - 0.001
>>>> seconds, so we wonder where is that half second spent in ? In our
>>>> application logic, in the case when the path is not correct, we throw
>>>> javax.ws.rs.WebApplicationException and with a debugger we saw that
>>>> this exception is getting caught in CXF, and heavily processed
>>>> further down the stack.
>>>>
>>>> Are you aware of such kind of issues, with CXF handling the 404
>>>> situation in a very heavyweight manner ? Maybe it does some thorough
>>>> processing to try to map the URI to some existing REST resource, I
>>>> don't know ... maybe performance here could depend on the particular
>>>> JSON framework that is being used. ...
>>>>
>>>
>>> I suspect it could be the default WebApplicationExceptionMapper which is
>>> to blame.
>>> In CXF, a given Exception, once wrapped in a Response, is treated like
>>> any other regular response, but I'm not sure it would explain the
>>> difference.
>>>
>>> Can you give me a favor please and register a custom
>>> WebApplicationException mapper which would only return:
>>>
>>> Response.status(exception.getStatus()).build() ?
>>>
>>> Have a look please at the default mapper's code:
>>> http://svn.apache.org/repos/asf/cxf/trunk/rt/frontend/jaxrs/src/main/java/org/apache/cxf/jaxrs/impl/WebApplicationExceptionMapper.java
>>>
>>>
>>> As you can see, we are trying to go to some length there to figure out
>>> what and how to report a given exception and I reckon it all adds up to
>>> the response time.
>>>
>>> Please try eliminating the default mapper and let us know the results
>>>
>>> Thanks, Sergey
>>>
>>>>
>>>> Kindest Regards,
>>>> Krum.
>>>>
>>>>
>>>
>>
>>
>
>
