Tomcat and Context.xml

Question

I am using Tomcat version 7.0.40.

Whenever there is an entry to context.xml, the context.xml reloads and redeploys the webapps since it is configured that way and is required to be that way. When a user hits a URL at this point, the page will be blank since reloading is still underway. My concern is - is there a way to determine when the reload is complete? Also, is there a way to display a meaningful message when the user hits a page during reload?

Answer 1

Editing the context.xml triggers an undeploy followed by a deploy rather than a reload. Currently, the brief period between the undeploy and the deploy will be treated as if no web application exists.

Handling this the same way a context reload is handled (essentially pausing the request until the redeploy is complete) might be possible but that would require code changes. The problem is non-trivial because
of the interactions between the Mapper, the Host, the HostConfig and the Context objects that would need to be coordinated. I suspect the complexity would not be worth the benefit when there is a simpler solution available.

Using parallel deployment and deploying a new version would mean the new version is deployed without any downtime and the old version can be removed at your leisure.

Comments

IIRC there was a bug in the past that during a *reload*, the webapp was temporarily unavailable and the ROOT context would be used. I modified our deployment procedure (which typically deploys a single webapp to a single Tomcat instance) to also deploy a trivial ROOT webapp with "/*" mapped to a "temporarily unavailable" page.

Would such a strategy cover the case above?