Can I use the same RoomDatabase object from multiple threads on Android?

I'm using the Room persistence library on Android. Currently, I have some extra synchronization code each time I access the database. I want to know if this code is necessary.

I currently access the database as a singleton. This is how I am currently inserting objects into the DB:

    // Insert values into DB
    final AppDatabase db = AppDatabase.get(this);
    AsyncTask.execute(new Runnable() {
        @Override
        public void run() {
            synchronized (db) {
                for (WorkOrder wo : workOrderList) {
                    db.workOrderDao().insertAll(wo);
                }
            }
        }
    });

Do I need to have the insertion code in a synchronized block?