private void debugLogSource(String source) {
        if (debugEnabled) {
            System.err.println("---------------------------------------");
            System.err.println("Source: ");
            System.err.println(source);
            System.err.println("---------------------------------------");
        }
    }
@return the size that each message takes up in bytes
jctools-channels/src/main/java/org/jctools/channels/mapping/Mapper.java