This caused a system-wide crash because of a previous bug relating to
non-trivial types in HashTable. Therefore, check that such types
actually work under various workloads.
Thrashing is what I call the situations where a table is mostly filled
with deleted markers, causing an increase in size (at least temporarily)
when a simple re-hash would be enough to get rid of those. This happens
when a hash table (especially with many elements) has a lot of deletes
and re-inserts done to it, which is what this benchmark does.
