6

I am having problems with get/set to an ElastiCache cluster from my EC2 instance. I am getting - SEVERE: net.spy.memcached.OperationTimeoutException: Timeout waiting for value - error.

When I am trying to get or set a value. I used the same code on my local machine (albeit communicating with a local memcached server) and everything works fine. The complete stacktrace can be found here - http://pastebin.com/tYcCJ6cj

I first saw that can I at least get the IP address of all the nodes of a cluster so that I can feed it in to my membase client & I am indeed able to find out the node ip addresses. I also made sure that all my EC2 security groups are added to the default cache cluster security group as well.

Any pointers on this will be greatly helpful.

UPDATE

Code snippet used to fetch a particular record.

public String getCachedValue(String namespace, String key) {
    String value = null;

    try {
        MemcachedClient client
            = CacheConnectionUtil.connectToElastiCacheMemcachedServer();

        // Point of origin for the exception.
        return (String) client.get(namespace + "$" + hashKey(key));        
    } catch (IOException e) {
        e.printStackTrace();
    }

    return value;
}

Code snippet used to connect to the ElastiCache server

private static MemcachedClient connectToElastiCacheMemcachedServer() 
    throws IOException {

    DescribeCacheClustersResult cacheClustersInfo = null;
    DescribeCacheClustersRequest cacheClusterRequest
         = new DescribeCacheClustersRequest();
    cacheClusterRequest.setShowCacheNodeInfo(true);

    try {
    cacheClustersInfo = AWSConnectionUtil
        .getElastiCacheObject(null)
        .describeCacheClusters(cacheClusterRequest);
    } catch (Exception e) {
        e.printStackTrace();
        throw new IOException("Unable to connect to ElastiCache Cluster.", e);
    }

    if (cacheClustersInfo == null) {
        throw new IOException("ElastiCache Cluster Info Object is null.");
    }

    List<CacheCluster> clusters = cacheClustersInfo.getCacheClusters();

    if (clusters == null || clusters.isEmpty()) {
        throw new IOException("No ElastiCache Clusters available.");
    }

    List<String> serverList = new ArrayList<String>();
    for (CacheCluster cluster : clusters) {
        if (cluster != null 
            && AWSConstants
                   .CACHE_CLUSTER_ID
                   .equalsIgnoreCase(cluster.getCacheClusterId())) {

            List<CacheNode> nodes = cluster.getCacheNodes();
            if (nodes != null ) {
                for (CacheNode node : nodes) {
                    if (node != null) {
                        Endpoint endpoint = node.getEndpoint();
                        if (endpoint != null
                            && endpoint.getAddress() != null) {
                            serverList.add(endpoint.getAddress()
                                           + ":"
                                           + endpoint.getPort());
                        }
                    }
                }
            }
        }
    }

    if (serverList.isEmpty()) {
        throw new IOException("No Cached nodes available for cluster - "
                              + AWSConstants.CACHE_CLUSTER_ID); 
    }

    return new MemcachedClient(AddrUtil.getAddresses(serverList));
}
BartoszKP
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Chantz
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  • Can you post your code? It's not possible to diagnose this problem without seeing what your doing. The stack trace just says the operation took too long to complete. – mikewied Nov 16 '11 at 05:05
  • @mikewied please see the updated question having code snippet. Thanks. – Chantz Nov 16 '11 at 14:01
  • Your code appears right and there is nothing that jumps out at me. I would just double check that the address/port combination is correct. If it is then try to telnet to one of the machines in you cluster from the same place this code is running and check to see if you can do a get. – mikewied Nov 16 '11 at 19:09
  • @mikewied yeah I actually took the ip address that is thrown in the stacktrace & use it to telnet fromn one of my ec2 instances, I can do a get, put properly. – Chantz Nov 16 '11 at 19:13
  • have you found what was the problem? – Hayati Guvence Jul 30 '12 at 15:33
  • @HayatiGuvence Actually No. I just reverted to using local memcached server. – Chantz Jul 30 '12 at 17:41

1 Answers1

0

Use the modified ElastiCache Cluster client produced by Amazon.

http://docs.aws.amazon.com/AmazonElastiCache/latest/UserGuide/AutoDiscovery.html#AutoDiscovery.ClusterClient

According to the documentation, to download the ElastiCache Cluster Client:

  1. Sign in to the AWS Management Console and open the ElastiCache console at https://console.aws.amazon.com/elasticache/.
  2. From the ElastiCache console, click Download ElastiCache Cluster Client.

The source code for the ElastiCache Cluster Client for Java is available at https://github.com/amazonwebservices/aws-elasticache-cluster-client-memcached-for-java. This library is based on the popular Spymemcached client. The ElastiCache Cluster Client is released under the Amazon Software License. You are free to modify the source code as you see fit; you can even incorporate the code into other open source Memcached libraries, or into your own client code.

Currently the version is 1.0.1. I have been using version 1.0 without any problems for over a year.

Peter
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