[marcodanti]

OK, I could verify that sticky sessions are working properly just by updating the native modules into httpd.

Reviewing the whole discussion, especially with regard to the AS-7.x compatibility, I think any update to modcluster from now on will be de facto incompatible with AS-7.

Yes, it will be 'compatible' for the native part, but this will not help when a bug fix will be in the server part.

Hoping I did not misunderstand something, we have:

• MODCLUSTER-288 removes a load metric that is not useful, but
• as a side effect it breaks compatibility with AS-7.x

If this is the actual picture, I'd rather have SystemMemoryLoadUsage restored back (maybe with some warning in the logs about it being useless/discouraged, or forcing it to always return 0, or any other remedy less devastating than MODCLUSTER-288) than leaving the AS-7.x users with a big problem....

[marcodanti]

The above discussion brought to surface a compatibility problem between mod_cluster-1.3.x + and AS-7.x, or at least this is my impression.

If this is true, this will be a major concern for every AS-7 user who can't upgrade their system to WildFly for any reason.

Has this issue being considered by the project? The only current workaround appears to be the one suggested by rhusar above, but that requires maintaining a custom build of the project, which not all users may be able to do.

[rhusar]

Reviewing the whole discussion, especially with regard to the AS-7.x compatibility, I think any update to modcluster from now on will be de facto incompatible with AS-7.

Yes, it will be 'compatible' for the native part, but this will not help when a bug fix will be in the server part.

The native part is backward compatible since it's using MCMP protocol. New versions of httpd modules will support new versions of MCMP along with old ones.

Also the upgrade process then requires upgrading first the native modules, then the container implementation.

The above discussion brought to surface a compatibility problem between mod_cluster-1.3.x + and AS-7.x, or at least this is my impression.

That was not the intention. AS 7.x is designed to be compatible with 1.2.x mod_cluster. There are many new releases after the original 1.2.0 release, e.g. the newest being https://github.com/modcluster/mod_cluster/tree/1.2.8.Final

WildFly 8.x is designed to be compatible with 1.3.x of mod_cluster.

Really, the incompatibility is going to happen sooner or later. You cannot keep compatibility forever, since it would prevent innovation. The removing of a metric is an unfortunate case, that the integration in AS 7.x is directly using those classes, but it really could use a more tolerant approach. Otherwise it would be nicely compatible.

The only current workaround appears to be the one suggested by Radoslav Husar above, but that requires maintaining a custom build of the project, which not all users may be able to do.

Unfortunately, this is always going to be the case with bleeding edge projects. Enterprise customers are already using EAP, new development is happening mostly on WildFly 8, targetting 8.0.1.Final release, or people are maintaning their own branches and building their own distribution.

[marcodanti]

Thanks for the clarification. I think I understand the general picture...I was using 1.2.6 on both sides up to now, and right at this moment I just count myself lucky that the fix I needed most (MODCLUSTER-359) just happened to be in the native part of 1.3.1.

We haven't even finished moving from Tomcat to AS-7; in our environment EAP will never be an option, and WildFly is perceived as being bleeding edge a bit too much. As you said, sooner or later AS-7 compatibility is bound to break anyway, it just seems unfair that it had to happen over a silly load metric.

Is 1.2.x just going to die, or is there any chance for major bug fixes being backported to 1.2.x as well...?

[rhusar]

We haven't even finished moving from Tomcat to AS-7; in our environment EAP will never be an option, and WildFly is perceived as being bleeding edge a bit too much. As you said, sooner or later AS-7 compatibility is bound to break anyway, it just seems unfair that it had to happen over a silly load metric.

I ll take a look if this can be integrated less tightly.

Is 1.2.x just going to die, or is there any chance for major bug fixes being backported to 1.2.x as well...?

All major bugs will be fixed in 1.2.x in the next couple of years.

[marcodanti]

Cool!  ...and many thanks for considering my concerns!