1. A computer-implemented method for cache management in a stream computing environment that uses a set of many-core hardware processors to process a stream of tuples by a plurality of processing elements which operate on the set of many-core hardware processors, the method comprising: detecting, for cache management in a stream computing environment, that a first cache and a second cache of a first core of a set of many-core hardware processors are local caches to the first core of the set of many-core hardware processors; ascertaining using a system hardware diagnostic, for cache management in the stream computing environment, that a second cache size of the second cache of the first core of the set of many-core hardware processors exceeds a first cache size of the first cache of the first core of the set of many-core hardware processors, the second cache size and the first cache size indicating an amount of data storage available to the first cache and the second cache; receiving a stream of tuples to be processed by a plurality of processing elements which operate on the set of many-core hardware processors; computing, for cache management in the stream computing environment, a first cache utilization factor for the first cache of the first core of the set of many-core hardware processors; computing, for cache management in the stream computing environment, a second cache utilization factor for the second cache of the first core of the set of many-core hardware processors; determining, based on a cache factor associated with the set of many-core hardware processors, a tuple-processing hardware-route on the set of many-core hardware processors; resolving, by comparing the first cache utilization factor for the first cache of the first core of the set of many-core hardware processors with the second cache utilization factor for the second cache of the first core of the set of many-core hardware processors, the tuple-processing hardware-route to prioritize utilization of the first cache of the first core of the set of many-core hardware processors with respect to the second cache of the first core of the set of many-core hardware processors; ascertaining, for cache management in the stream computing environment, that a second cache access burden of the second cache of the first core of the set of many-core hardware processors exceeds a first cache access burden of the first cache of the first core of the set of many-core hardware processors; routing, based on the tuple-processing hardware-route on the set of many-core hardware processors, the stream of tuples; prioritizing, pertaining to processing the stream of tuples utilizing the set of many-core hardware processors, the first cache of the first core of the set of many-core hardware processors with respect to the second cache of the first core of the set of many-core hardware processors; and processing, utilizing the set of many-core hardware processors, the stream of tuples by the plurality of processing elements which operate on the set of many-core hardware processors.