If your web app starts serving stale cached content when run behind mod_jk or mod_proxy with apache, it may be due to apache inserting a default expiration header.
You can confirm this by comparing the headers returned from apache and directly from your web app. curl -i will show response headers:
curl -i http://example.com | head -20
To disable apache’s content expirations, add the following to your virtual host:
Here is the official Apache Documentation.