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From Sznajder ForMailingList <bs4mailingl...@gmail.com>
Subject Re: Multiple consumers on a single server - strange behavior.
Date Sun, 17 Nov 2013 21:53:15 GMT
Hi Jordan,

Thanks again for your so quick answer.

I would like to be sure about your hint.

Do you mean that I should change the following method

            @Override
            public void consumeMessage(CrawlUrl url) throws Exception {
                try {
                    LOG.info(dateFormat.format(new
Date(System.currentTimeMillis())) + "["+id+ "-" + MyQueueConsumer.this.name+
"] processed " + url.url);
                    MyQueueConsumer.this.numberOfProcessedURL++;
                } catch (Exception e) {
                    LOG.error( "["+id+ "-" + MyQueueConsumer.this.name+ "]"
+ e.getMessage() + " for url " + url.url );
                }
            }



or the code in the QueueProducer?

In this last case (code in the QueueProducer), I think it will not solve
the problem: I can see in my logs that the consumers are idle even when the
Producer does not do anything...

Best regards

Benjamin




On Sun, Nov 17, 2013 at 11:33 PM, Jordan Zimmerman <
jordan@jordanzimmerman.com> wrote:

> I’ll look further at this, but the first thing that I notice is that you
> are doing “work” in your Curator Listener. Please read Curator Tech Note 1:
>
> https://cwiki.apache.org/confluence/display/CURATOR/TN1
>
> The quickest fix would be to do the getChildren() as a background
> operation. Alternatively, you can pass in a thread pool when registering
> the listener.
>
> -Jordan
>
> On Nov 17, 2013, at 1:20 PM, Sznajder ForMailingList <
> bs4mailinglist@gmail.com> wrote:
>
> First at all , thank you for your answer.
>
> Here is the simple code, I used:
>
> The producer and queueconsummer are given in the class
>
> Every 5 minutes, I am printing the the number of processed items, and I
> see some drastic differences between the different consumers:
>
>
>
> Producer:
> =-=-=-=-=
>
> package com.zk;
>
> import java.io.Closeable;
> import java.io.IOException;
> import java.text.DateFormat;
> import java.text.SimpleDateFormat;
> import java.util.Date;
> import java.util.List;
>
> import org.apache.curator.framework.CuratorFramework;
> import org.apache.curator.framework.api.CuratorEvent;
> import org.apache.curator.framework.api.CuratorListener;
> import org.apache.curator.framework.recipes.queue.DistributedQueue;
> import org.apache.curator.test.TestingServer;
> import org.slf4j.Logger;
> import org.slf4j.LoggerFactory;
>
>
> public class QueueProducer implements Closeable {
>
>     final static Logger LOG = LoggerFactory.getLogger(QueueProducer.class);
>
>     final static DateFormat dateFormat = new SimpleDateFormat("HH:mm:ss");
>
>     protected static final String PATH = "/test_queue";
>
>     protected static final String LOCK_PATH = "/test_lock_queue";
>
>     private DistributedQueue<CrawlUrl> queue;
>
>     private static final int QUEUE_SIZE = 100000;
>
>     private int items;
>
>     public QueueProducer(CuratorFramework framework) throws Exception {
>         LOG.info(java.net.InetAddress.getLocalHost().getHostName() + " is
> a QueueProducer");
>
> System.out.println(java.net.InetAddress.getLocalHost().getHostName() + " is
> a QueueProducer");
>         this.queue = Utils.newDistributedQueue(framework,
>                 Utils.CRAWL_QUEUE_PATH, Utils.CRAWL_QUEUE_LOCK_PATH, null);
>         this.queue.start();
>         addQueueContent(QUEUE_SIZE);
>         System.out.println("Done with the initial init");
>
>
>         // We register to the listener for monitoring the number of
> elements
>         // in the queue
>         framework.getCuratorListenable().addListener(new CuratorListener()
> {
>             @Override
>             public void eventReceived(final CuratorFramework framework_,
>                     CuratorEvent event) throws Exception {
>                 if (event.getPath() != null    &&
> event.getPath().equals(Utils.CRAWL_QUEUE_PATH)) {
>                     // this also restores the notification
>                     List<String> children = framework_.getChildren()
>                             .watched().forPath(Utils.CRAWL_QUEUE_PATH);
>                     if (children.size() <= QUEUE_SIZE/2) {
>                         addQueueContent(QUEUE_SIZE - children.size());
>                     }
>                 }
>             }
>         });
>
>
>         while (true) {
>             List<String> children =
> framework.getChildren().watched().forPath(Utils.CRAWL_QUEUE_PATH);
>             if (children.size() <= QUEUE_SIZE/2) {
>                 LOG.info(dateFormat.format(new Date()) + " - In the
> while(true) - We call for size " + children.size());
>                 addQueueContent(QUEUE_SIZE - children.size());
>             }
>
>             Thread.sleep(5000);
>
>         }
>     }
>
>     void addQueueContent(int numberOfItems) {
>         LOG.info(dateFormat.format(new Date()) + " - addQueueContent " +
> numberOfItems);
>         for (int i = 0; i < numberOfItems; i++) {
>             try {
>                 CrawlUrl url = new CrawlUrl(""+this.items++);
>                 this.queue.put(url);
>             } catch (Exception e) {
>                 LOG.error ("Caught an error when adding the item " + i + "
> in the initQueueContent()");
>             }
>         }
>     }
>
>     public static void main(String[] args) {
>         CrawlerPropertyFile props;
>         try {
>             props = new CrawlerPropertyFile(args[0]);
>
>             final String connectString;
>             System.out.println("DEBUG = " + Utils.DEBUG);
>             if (props.useZkTestServer()) {
>                 System.out.println("Will launch from zkTestServer");
>                 TestingServer server = new TestingServer();
>                 connectString = server.getConnectString();
>             } else {
>                 connectString = props.getZkServer();
>             }
>
>             final CuratorFramework framework =
> Utils.newFramework(connectString);
>             framework.start();
>
>             @SuppressWarnings("unused")
>             QueueProducer producer = new QueueProducer(framework);
>         } catch (Exception e) {
>             e.printStackTrace();
>         }
>
>     }
>
>     @Override
>     public void close() throws IOException {
>         this.queue.close();
>     }
>
>
>
> }
>
>
>
>
> Consumer
> =-=-=-=-=-
>
> package com.zk;
>
> import java.io.Closeable;
> import java.io.File;
> import java.io.FileWriter;
> import java.io.IOException;
> import java.text.DateFormat;
> import java.text.SimpleDateFormat;
> import java.util.Date;
>
> import org.apache.curator.framework.CuratorFramework;
> import org.apache.curator.framework.recipes.queue.DistributedQueue;
> import org.apache.curator.framework.recipes.queue.QueueConsumer;
> import org.apache.curator.framework.state.ConnectionState;
> import org.apache.curator.test.TestingServer;
> import org.slf4j.Logger;
> import org.slf4j.LoggerFactory;
>
>
>
> public class MyQueueConsumer implements Closeable{
>
>     private DistributedQueue<CrawlUrl> queue;
>
>     String name;
>
>     String id;
>
>     FileWriter timeCounter;
>
>     final static Logger LOG =
> LoggerFactory.getLogger(MyQueueConsumer.class);
>
>     final static DateFormat dateFormat = new SimpleDateFormat("HH:mm:ss");
>
>     int numberOfProcessedURL;
>
>     private com.zk.MyQueueConsumer.FileWriterThread timeCounterThread;
>
>     private class FileWriterThread extends Thread {
>
>         public FileWriterThread() {
>             // empty ctor
>         }
>
>         @Override
>         public void run() {
>             // We write the stats:
>
>             try {
>                 while (true) {
>
> MyQueueConsumer.this.timeCounter.write(dateFormat.format(new Date()) + " "+
>
> "[numberOfProcessed="+MyQueueConsumer.this.numberOfProcessedURL    +"]\n") ;
>                     MyQueueConsumer.this.timeCounter.flush();
>
>                     // Sleeps 5 minutes
>                     Thread.sleep(300000);
>                 }
>             } catch (Exception e) {
>                 // TODO Auto-generated catch block
>                 e.printStackTrace();
>             }
>         }
>     }
>
>
>     public MyQueueConsumer(CuratorFramework framework, final String id)
> throws Exception {
>         this.id = id;
>         this.name = java.net.InetAddress.getLocalHost().getHostName();
>         this.timeCounter = new FileWriter(new File("MyQueueConsumer_"+
> this.name + "_" +id + "_timeCounter.txt"));
>
> //        this.timeCounterThread = new FileWriterThread();
> //        this.timeCounterThread.start();
>         this.queue = Utils.newDistributedQueue(framework,
> Utils.CRAWL_QUEUE_PATH, Utils.CRAWL_QUEUE_LOCK_PATH, new
> QueueConsumer<CrawlUrl>() {
>
>             @Override
>             public void stateChanged(CuratorFramework client,
> ConnectionState newState) {
>                 System.out.println(String.format("[%s] connection state
> changed to %s", id, newState));
>             }
>
>             @Override
>             public void consumeMessage(CrawlUrl url) throws Exception {
>                 try {
>                     LOG.info(dateFormat.format(new
> Date(System.currentTimeMillis())) + "["+id+ "-" +
> MyQueueConsumer.this.name <http://myqueueconsumer.this.name/>+ "]
> processed " + url.url);
>                     MyQueueConsumer.this.numberOfProcessedURL++;
>                 } catch (Exception e) {
>                     LOG.error( "["+id+ "-" + MyQueueConsumer.this.name<http://myqueueconsumer.this.name/>+
> "]" + e.getMessage() + " for url " + url.url );
>                 }
>             }
>
>         });
>         try {
>             this.queue.start();
>         } catch (Exception e) {
>             e.printStackTrace();
>         }
>
>     }
>
>     public static void main(String[] args) {
>         try {
>             CrawlerPropertyFile props = new CrawlerPropertyFile(args[0]);
>
>             final String connectString;
>             System.out.println("DEBUG = " + Utils.DEBUG);
>             if (props.useZkTestServer()) {
>                 System.out.println("Will launch from zkTestServer");
>                 TestingServer server = new TestingServer();
>                 connectString = server.getConnectString();
>             } else {
>                 connectString = props.getZkServer();
>             }
>
>             final CuratorFramework framework =
> Utils.newFramework(connectString);
>             framework.start();
>
>             final MyQueueConsumer[] queueConsumers = new
> MyQueueConsumer[props.getNumberOfWorkers()];
>
>             for (int i = 0; i < queueConsumers.length; i++) {
>                 queueConsumers[i] = new MyQueueConsumer(framework,
> "id_"+i);
>             }
>
>             Runtime.getRuntime().addShutdownHook(new Thread() {
>                 @Override
>                 public void run() {
>                     // close workers
>                     Throwable t = null;
>                     LOG.info("We close the workers");
>                     for (MyQueueConsumer queueConsumer : queueConsumers) {
>                         try {
>                             queueConsumer.close();
>                         } catch (Throwable th) {
>                             if (t == null) {
>                                 t = th;
>                             }
>                         }
>                     }
>                     // throw first exception that we encountered
>                     if (t != null) {
>                         throw new RuntimeException("some workers failed to
> close", t);
>                     }
>                 }
>             });
>
>         }catch (Exception e ){
>             e.printStackTrace();
>         }
>     }
>
>     @Override
>     public void close() throws IOException {
>         this.queue.close();
>     }
> }
>
>
>
>
> Main
> -=-=-
>
> package com.zk;
>
> import org.apache.curator.framework.CuratorFramework;
> import org.apache.curator.test.TestingServer;
>
>
>
> public class QueueTestMain {
>
>     /**
>      * @param args
>      */
>     public static void main(String[] args) {
>         CrawlerPropertyFile props;
>         try {
>             props = new CrawlerPropertyFile(args[0]);
>
>             final String connectString;
>             System.out.println("DEBUG = " + Utils.DEBUG);
>             if (props.useZkTestServer()) {
>                 System.out.println("Will launch from zkTestServer");
>                 TestingServer server = new TestingServer();
>                 connectString = server.getConnectString();
>             } else {
>                 connectString = props.getZkServer();
>             }
>
>             final CuratorFramework framework =
> Utils.newFramework(connectString);
>             framework.start();
>
>
>             if (args[1] != null && args[1].equalsIgnoreCase("true")) {
>                 @SuppressWarnings("unused")
>                 QueueProducer producer = new QueueProducer(framework);
>             } else {
>
>                 final MyQueueConsumer[] queueConsumers = new
> MyQueueConsumer[props.getNumberOfWorkers()];
>
>                 for (int i = 0; i < queueConsumers.length; i++) {
>                     queueConsumers[i] = new MyQueueConsumer(framework,
> "id_"+i);
>                 }
>
>                 Runtime.getRuntime().addShutdownHook(new Thread() {
>                     @Override
>                     public void run() {
>                         // close workers
>                         Throwable t = null;
>                         for (MyQueueConsumer queueConsumer :
> queueConsumers) {
>                             try {
>                                 queueConsumer.close();
>                             } catch (Throwable th) {
>                                 if (t == null) {
>                                     t = th;
>                                 }
>                             }
>                         }
>                         // throw first exception that we encountered
>                         if (t != null) {
>                             throw new RuntimeException("some workers
> failed to close", t);
>                         }
>                     }
>                 });
>
>
>             }
>         }catch (Exception e ){
>             e.printStackTrace();
>         }
>
>     }
>
> }
>
>
>
>
> Example of output:
>
>
>
>
>
> On Sun, Nov 17, 2013 at 10:14 PM, Jordan Zimmerman <
> jordan@jordanzimmerman.com> wrote:
>
>> Can you produce a test that shows this? Anything else interesting in the
>> log? Of course, there could be a bug.
>>
>> -Jordan
>>
>> On Nov 14, 2013, at 1:18 PM, Sznajder ForMailingList <
>> bs4mailinglist@gmail.com> wrote:
>>
>> > Hi
>> >
>> > I made a short test as following:
>> >
>> > - I have a chorum of 3 nodes for Zookeeper.
>> > - I wrote a class using Curator QueueProducer who produces all the time
>> (when the queue is 10% full, it creates new items) , items (random integer)
>> > - I wrote a simple class using Curator Queue Consumer which simply
>> prints to Log "consumed item i".
>> >
>> > I tested some different combinations :
>> > - running the consumers on one, two or three nodes.
>> > - running one or more consumers in parallel on a given node.
>> >
>> >
>> > But, and here is my question: I see some very strange behavior when I
>> have several consummers in parallel on a node. For example, running 5
>> consumers per node on 3 nodes, I see a throughput **very** slow. When
>> looking at my Log, I see that most of the consumers are most of the time on
>> an idle state....
>> >
>> > Do I mistake somewhere?
>> >  I was expecting to enhance the throughput by augmenting the number of
>> consumers, I am surprised to see the opposite....
>> >
>> > Thanks a lot
>> >
>> > Benjamin
>>
>>
>
>

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