Software-based cache coherence protocol. A processing unit may execute a memory request using a processor thread. In response to detecting a cache hit to shared or a cache miss associated with the memory request, a cache may provide both a trap signal and coherence information to the processor thread of the processing unit. After receiving the trap signal and the coherence information, the processor thread may perform a cache coherence operation for the memory request using at least the received coherence information. The processing unit may include a plurality of processor threads and a load balancer. The load balancer may receive coherence requests from one or more remote processing units and distribute the received coherence requests across the plurality of processor threads. The load balance may preferentially distribute the received coherence requests across the plurality of processor threads based on the operation state of the processor threads.