presto-memory-context/src/main/java/io/prestosql/memory/context/MemoryTrackingContext.java/MemoryTrackingContext/localSystemMemoryContext
class MemoryTrackingContext:    public LocalMemoryContext localSystemMemoryContext()
    {
        verifyNotNull(systemLocalMemoryContext, "local memory contexts are not initialized");
        return systemLocalMemoryContext;
    }