Lately I did lots of DB2 event monitoring, snapshot, Java dump on a troubled page. From the logs, I see 2 threads coming in as click on a href. Eventually I got suspicious with IBM IHS. Tailing -f access_log reveals 2 HTTP GET sent from a single a href.
Today we finally found the harmful <img src="">. It is inside a JSP which will post to /wcs/stores/servlet/. This will put a load on our DB2 esp needs a X lock on some tables.
One of my teammate who has been working on the projects told me she had known this problem for a year. She has no idea why an extra HTTP GET comes in. Now we know why.