1. Better logging and error reporting;
2. Worker process title;
3. Some comments

Worker process title example:

 446209 pts/2    R+     0:00 mysql-test-run.pl worker[01] :42146 -> :35027 versioning.view
 446210 pts/2    S+     0:00 mysql-test-run.pl worker[02] :42150 -> :35027 versioning.view
 446211 pts/2    S+     0:00 mysql-test-run.pl worker[03] :42154 -> :35027 versioning.foreign
 446212 pts/2    S+     0:00 mysql-test-run.pl worker[04] :42160 -> :35027 versioning.autoinc

Manager-worker localhost socket connection is represented by a pair :source -> :destination ports.

-vv Now adds --verbose to mysqltest as well, see var/mysqltest.log for the output.