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