As part of introducing the defragmentation policy, we introduced new threads in the balancer. These different threads are using the same random_device to shuffle different vectors, causing data races.

Currently, we are using std::random_device in:

• balancer_chunk_selection_policy_impl.cpp
• balancer_chunk_selection_policy_impl.cpp
• balancer_defragmentation_policy_impl.cpp
• balancer.cpp

We instead need to use the Client local Prng when using std::shuffle as:

Client * client = ...;
std::shuffle(begin, end, client->getPrng().urbg());

With this implementation, we will not worry about thread-safety because the RNG is thread-local.