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Is your WAR file deployed in exploded format or is it deployed in an archive format?
If its deployed in exploded format, then the server keeps an watch on the web.xml file to see if the last modified time of this file has changed. If the timestamp has changed the the hotdeployer picks up this application and redeploys it.
In case of archived applications - change in timestamp of the archive will be tracked. Or even deleting the existing war and placing the application back in the deploy folder triggers the redeployment.
So is something like this happening with your application?
Finally, you can even disable hot deployment. Set the ScanEnabled under the DeploymentScanner MBean to false, in %JBOSS_HOME%/server/< serverName>/conf/jboss-service.xml file: