Re: Large webapps in 7.0.29 and Annotation Scanning not respecting metadata-complete
Andreas Pålsson wpt2...@hotmail.com wrote: I have been thinking about this issue all day, and I think the specification needs more work on this area. There is certainly no need for a container to wade through hundreds maybe even thousands of classes in search of something that does not exist. It is an unnecessary task which consumes both time and resources. I am all for making it easier for a developer, and make the container scan everything by default. But there is also an obvious need for a solution to specifically define where a container should look for annotations when we have web applications with very large amount of classes. Even if it has to be an XML-file, such as in Spring where you can instruct the framework where to look for beans, entities, controllers and such. Mark, is there a way we can influence the EG to change this? Thanks. - To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org For additional commands, e-mail: users-h...@tomcat.apache.org The bad news is that this is a 3.0 feature so we are way past being able to influence it. Personally I dislike most of the 3.0 pluggability featutes. If you have ideas how to improve things then the EG lists Rainer pointed you to is the place to take them. Mark - To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org For additional commands, e-mail: users-h...@tomcat.apache.org
Re: Large webapps in 7.0.29 and Annotation Scanning not respecting metadata-complete
On 01/08/2012 02:53, andreas palsson wrote: Good morning. After upgrading to 7.0.29, one of my larger webapps could no longer be deployed due to OutOfMemoryError. As far as I know, this is related to the new feature of annotation scanning which was enabled in v7.0.29 (see the stack trace below). Have anyone else experienced the same issue? There are multiple issues going on here. There have been reported previously and are understood. I'll try and explain the full story. The servlet spec requires (and the expert group (EG) confirmed) that Tomcat always scans for ServletContainerInitializers (SCIs), even if metadata-complete is true. Tomcat was changed to do this in 7.0.29. SCIs can have @HandlesTypes annotations. If one is present, Tomcat must scan every class and its hierarchy looking for matches to the HandlesTypes. Tomcat caches the results of this scan to speed up processing so it doesn't repeatedly scan the same classes. If A B both inherit from C, when Tomcat scans A it also scans C and caches the result so it doesn't have to scan C again when checking B. Tomcat was caching more than it needed to making the cache excessively large. This is bug 53535 which has already been fixed and will be in 7.0.30 onwards. This then raises the question of how to turn of scanning for classes that match HandlesTypes. While the spec says that JARs excluded using an absolute-ordering are not scanned for matches to HandlesTypes it was unclear what is meant to happen when metadata-complete is true since ordering is ignored in that case. The EG has recently clarified this and stated that JARs excluded using an absolute-ordering are not scanned for matches to HandlesTypes regardless of the setting of metadata-complete. The discussion is not yet complete and we are waiting for it to conclude and before implementing the results of that discussion in 7.0.30. Mark - To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org For additional commands, e-mail: users-h...@tomcat.apache.org
RE: Large webapps in 7.0.29 and Annotation Scanning not respecting metadata-complete
Thank you Mark for explaining this. I'll see if I can get my hands on a 7.0.30 and see how it works out. One thing though, would it be possible to allow Tomcat to _only_ scan for SCI's in WEB-INF/classes and exclude WEB-INF/lib (even for parent classes inherited in the former)? It would be great to have some control over the SCI's as some could be located in any of the dependencies I have added to the application. // andreas Date: Wed, 1 Aug 2012 08:51:04 +0100 From: ma...@apache.org To: users@tomcat.apache.org Subject: Re: Large webapps in 7.0.29 and Annotation Scanning not respecting metadata-complete There are multiple issues going on here. There have been reported previously and are understood. I'll try and explain the full story. [...] Mark
Re: Large webapps in 7.0.29 and Annotation Scanning not respecting metadata-complete
On 01/08/2012 09:35, andreas palsson wrote: Thank you Mark for explaining this. I'll see if I can get my hands on a 7.0.30 and see how it works out. You'll need to wait until all the issues have been fixed and then build from trunk. Keep an eye on the dev list. One thing though, would it be possible to allow Tomcat to _only_ scan for SCI's in WEB-INF/classes and exclude WEB-INF/lib (even for parent classes inherited in the former)? It would be great to have some control over the SCI's as some could be located in any of the dependencies I have added to the application. No. You can exclude SCIs in JARs through absolute ordering but you can't stop Tomcat scanning WEB-INF/classes for matching types. Mark // andreas Date: Wed, 1 Aug 2012 08:51:04 +0100 From: ma...@apache.org To: users@tomcat.apache.org Subject: Re: Large webapps in 7.0.29 and Annotation Scanning not respecting metadata-complete There are multiple issues going on here. There have been reported previously and are understood. I'll try and explain the full story. [...] Mark - To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org For additional commands, e-mail: users-h...@tomcat.apache.org
Re: Large webapps in 7.0.29 and Annotation Scanning not respecting metadata-complete
On 01.08.2012 09:51, Mark Thomas wrote: On 01/08/2012 02:53, andreas palsson wrote: Good morning. After upgrading to 7.0.29, one of my larger webapps could no longer be deployed due to OutOfMemoryError. As far as I know, this is related to the new feature of annotation scanning which was enabled in v7.0.29 (see the stack trace below). Have anyone else experienced the same issue? There are multiple issues going on here. There have been reported previously and are understood. I'll try and explain the full story. The servlet spec requires (and the expert group (EG) confirmed) that Tomcat always scans for ServletContainerInitializers (SCIs), even if metadata-complete is true. Tomcat was changed to do this in 7.0.29. SCIs can have @HandlesTypes annotations. If one is present, Tomcat must scan every class and its hierarchy looking for matches to the HandlesTypes. Tomcat caches the results of this scan to speed up processing so it doesn't repeatedly scan the same classes. If A B both inherit from C, when Tomcat scans A it also scans C and caches the result so it doesn't have to scan C again when checking B. Tomcat was caching more than it needed to making the cache excessively large. This is bug 53535 which has already been fixed and will be in 7.0.30 onwards. This then raises the question of how to turn of scanning for classes that match HandlesTypes. While the spec says that JARs excluded using an absolute-ordering are not scanned for matches to HandlesTypes it was unclear what is meant to happen when metadata-complete is true since ordering is ignored in that case. The EG has recently clarified this and stated that JARs excluded using an absolute-ordering are not scanned for matches to HandlesTypes regardless of the setting of metadata-complete. The discussion is not yet complete and we are waiting for it to conclude and before implementing the results of that discussion in 7.0.30. Would *.jar in jarsToSkip (catalina.properties) be a workaround, or is that skip list also ignored for SCI / @HandlesTypes processing? Regards, Rainer - To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org For additional commands, e-mail: users-h...@tomcat.apache.org
Re: Large webapps in 7.0.29 and Annotation Scanning not respecting metadata-complete
I have been thinking about this issue all day, and I think the specification needs more work on this area. There is certainly no need for a container to wade through hundreds maybe even thousands of classes in search of something that does not exist. It is an unnecessary task which consumes both time and resources. I am all for making it easier for a developer, and make the container scan everything by default. But there is also an obvious need for a solution to specifically define where a container should look for annotations when we have web applications with very large amount of classes. Even if it has to be an XML-file, such as in Spring where you can instruct the framework where to look for beans, entities, controllers and such. Mark, is there a way we can influence the EG to change this? Thanks. - To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org For additional commands, e-mail: users-h...@tomcat.apache.org
Re: Large webapps in 7.0.29 and Annotation Scanning not respecting metadata-complete
On 01.08.2012 18:10, Andreas Pålsson wrote: I have been thinking about this issue all day, and I think the specification needs more work on this area. There is certainly no need for a container to wade through hundreds maybe even thousands of classes in search of something that does not exist. It is an unnecessary task which consumes both time and resources. I am all for making it easier for a developer, and make the container scan everything by default. But there is also an obvious need for a solution to specifically define where a container should look for annotations when we have web applications with very large amount of classes. Even if it has to be an XML-file, such as in Spring where you can instruct the framework where to look for beans, entities, controllers and such. Mark, is there a way we can influence the EG to change this? I'm not Mark and don't want to preempt any answer from him, but there is the following public discussion available: http://java.net/jira/browse/SERVLET_SPEC-36 and http://java.net/jira/browse/SERVLET_SPEC-36 Regards, Rainer - To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org For additional commands, e-mail: users-h...@tomcat.apache.org
Re: Large webapps in 7.0.29 and Annotation Scanning not respecting metadata-complete
On 01.08.2012 18:52, Rainer Jung wrote: Mark, is there a way we can influence the EG to change this? I'm not Mark and don't want to preempt any answer from him, but there is the following public discussion available: http://java.net/jira/browse/SERVLET_SPEC-36 and http://java.net/jira/browse/SERVLET_SPEC-36 Grrr, the second link should have been: http://java.net/projects/servlet-spec/lists/jsr340-experts/archive/2012-07/message/28 Regards, Rainer - To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org For additional commands, e-mail: users-h...@tomcat.apache.org
