Minor Description
Right now the WALPerformaceEvaluation tool sets up each new region by asking for a WAL and then adding a listener. The listener updates running stats on appends / syncs using a shared object in the evaluation tool.
For WALProviders that reuse WALs (such as the default one always using a single WAL), this results in adding a listener to WALs that already have them. Each of those listeners is then updated on each append/sync.