Can the ArcGIS Web Adapter version 10.5.1 and above be deployed on WildFly or any other java container platforms in lieu of running it on local instances of Apache Tomcat 7/8? we are concerned about performance.
JBoss Enterprise Application Platform 7 is supported for the web adaptor at ArcGIS 10.6. My understanding is that the JBoss Community project was renamed to Wildfly to differentiate between the Enterprise and Community projects.
That said, I haven't explicitly tested. Honestly, I'd be a little surprised if you were able to achieve much of a performance improvement. The web adaptor is very lightweight - it's essentially a proxy server that forwards requests with a simple round-robin load balancing (if you have multiple GIS Servers in your site).
Janie, as Randall stated above we officially support "JBoss Enterprise Application Platform 7": ArcGIS Web Adaptor 10.5.x system requirements—ArcGIS Enterprise system requirements | ArcGIS Enterpr...
That being said, it is technically possible to do so and I have deployed on Wildfly 11 on numerous occasions for setup of test environments. There are some quirks (for example, certain pages in Server Manager not appearing correctly) but these are usually browser-specific.
I have to agree with Randall that the performance boost is probably negligible in this case as you should also consider the hit you'll take if you're running the full-blown JEE stack version. I'm not sure about your needs but if you're set on not using Apache Tomcat, I would recommend: