def _get_pools(resource_name: str) -> (ThreadPool, RegisteredResourcePool):
pool_name = resource_name
with _pools_lock:
if pool_name not in _combined_pools:
# create and cache new thread pool and resource pool for the resource,
# they are of the same size, so that each thread can always pick a resource
resource_factory = ResourceFactory(resource_name)
# note that the hard limit on the resource pool size is greater than the number
# of worker threads, this way worker threads still have each its guaranteed resource
# instance whenever necessary, but the sweeper threads also can have their busy slots
# whenever they intervene for removing the expired connections or warming the pool up
thread_pool = ThreadPool(resource_name, resource_factory.pool_size)
resource_pool = RegisteredResourcePool(resource_name, resource_factory,
resource_factory.pool_size + 2,
resource_factory.pool_standby,
resource_factory.pool_cache)
_combined_pools[pool_name] = (thread_pool, resource_pool)
return _combined_pools[pool_name]
