Sorry for the late answer. Please reopen the issue.

Neither the improved token mechanism, nor the SNAPSHOT version did solve the issue. I manged to test it with H2, and I couldn't reproduce the problem. I guess that MySQL is slower a bit, or behaves somewhat differently, and it brings up a hidden race condition issue.

I can help debugging if you cannot reproduce it. You can send me instrumented picketlink files, or instructions to enable debug mode.