SGEM is a scalable semantic graph databse. The software platform comprises three major components: 1) a SPARQL to C compiler, 2) a mulithreaded graph library (SGLib), and 3) a custom mulithreaded runtime layer (GMT). The compiler converts SPARQL queries to data parallel C code with calls to SGLib and GMT methods. SGLib is a llibrary of graph methods and data structures. It includes methods to ingest RDF triple files, store data in a compressed neighbor graph, and multithreaded graph algorithms customized for query processing and GMT. GMT is a mulithreaded runtime system for comoodity servers, clusters, and cloud systems customized for query processing. GMT manages a global address space, tread scheduling, and data aggregation.