Not receiving ack in this storm topology? - apache-storm

Question

I am new with storm, and I am running a toplogy
public class FakeCallLogReaderSpout implements IRichSpout {
//Create instance for SpoutOutputCollector which passes tuples to bolt.
private SpoutOutputCollector collector;
private boolean completed = false;
//Create instance for TopologyContext which contains topology data.
private TopologyContext context;
//Create instance for Random class.
private Random randomGenerator = new Random();
private Integer idx = 0;
#Override
public void open(Map conf, TopologyContext context, SpoutOutputCollector collector) {
this.context = context;
this.collector = collector;
}
#Override
public void nextTuple() {
if(this.idx <= 1000) {
List<String> mobileNumbers = new ArrayList<String>();
mobileNumbers.add("1234123401");
mobileNumbers.add("1234123402");
mobileNumbers.add("1234123403");
mobileNumbers.add("1234123404");
Integer localIdx = 0;
while(localIdx++ < 100 && this.idx++ < 1000) {
String fromMobileNumber = mobileNumbers.get(randomGenerator.nextInt(4));
String toMobileNumber = mobileNumbers.get(randomGenerator.nextInt(4));
while(fromMobileNumber == toMobileNumber) {
toMobileNumber = mobileNumbers.get(randomGenerator.nextInt(4));
}
Integer duration = randomGenerator.nextInt(60);
this.collector.emit(new Values(fromMobileNumber, toMobileNumber, duration),duration);
}
}
}
#Override
public void declareOutputFields(OutputFieldsDeclarer declarer) {
declarer.declare(new Fields("from", "to", "duration"));
}
//Override all the interface methods
#Override
public void close() {}
public boolean isDistributed() {
return false;
}
#Override
public void activate() {}
#Override
public void deactivate() {}
#Override
public void ack(Object msgId) {
System.out.println(msgId);
}
#Override
public void fail(Object msgId) {}
#Override
public Map<String, Object> getComponentConfiguration() {
return null;
}
}
//Create a class CallLogCreatorBolt which implement IRichBolt interface
public class CallLogCreatorBolt implements IRichBolt {
//Create instance for OutputCollector which collects and emits tuples to produce output
private OutputCollector collector;
#Override
public void prepare(Map conf, TopologyContext context, OutputCollector collector) {
this.collector = collector;
}
#Override
public void execute(Tuple tuple) {
String from = tuple.getString(0);
String to = tuple.getString(1);
Integer duration = tuple.getInteger(2);
collector.emit(new Values(from + " - " + to, duration));
}
#Override
public void cleanup() {}
#Override
public void declareOutputFields(OutputFieldsDeclarer declarer) {
declarer.declare(new Fields("call", "duration"));
}
#Override
public Map<String, Object> getComponentConfiguration() {
return null;
}
}
public class CallLogCounterBolt implements IRichBolt {
Map<String, Integer> counterMap;
private OutputCollector collector;
#Override
public void prepare(Map conf, TopologyContext context, OutputCollector collector) {
this.counterMap = new HashMap<String, Integer>();
this.collector = collector;
}
#Override
public void execute(Tuple tuple) {
String call = tuple.getString(0);
Integer duration = tuple.getInteger(1);
if(!counterMap.containsKey(call)){
counterMap.put(call, 1);
}else{
Integer c = counterMap.get(call) + 1;
counterMap.put(call, c);
}
collector.ack(tuple);
}
#Override
public void cleanup() {
for(Map.Entry<String, Integer> entry:counterMap.entrySet()){
System.out.println(entry.getKey()+" : " + entry.getValue());
}
}
#Override
public void declareOutputFields(OutputFieldsDeclarer declarer) {
declarer.declare(new Fields("call"));
}
#Override
public Map<String, Object> getComponentConfiguration() {
return null;
}
}
I am calling collector.ack(tuple) from CallLogCounterBolt, the but ack is not getting called.
Does anybody have any idea why it is not getting called?
Also if drop the ack altogether from the code, what impact will it have?

Answer 1

You need to anchor and ack tuple in each bolt. I guess your topology is like FakeCallLogReaderSpout => CallLogCreatorBolt=> CallLogCounterBolt. Thus, in CallLogCreatorBolt you should do
collector.emit(tuple, new Values(from + " - " + to, duration));
collector.ack();
Read https://storm.apache.org/releases/0.10.0/Guaranteeing-message-processing.html for more details.