Package org.apache.solr.client.solrj.impl

Class LBHttpSolrClient

  • All Implemented Interfaces:
    Closeable, Serializable, AutoCloseable
    public class LBHttpSolrClient
extends SolrClient
    LBHttpSolrClient or "LoadBalanced HttpSolrClient" is a load balancing wrapper around HttpSolrClient. This is useful when you have multiple Solr servers and the requests need to be Load Balanced among them. Do NOT use this class for indexing in master/slave scenarios since documents must be sent to the correct master; no inter-node routing is done. In SolrCloud (leader/replica) scenarios, it is usually better to use CloudSolrClient, but this class may be used for updates because the server will forward them to the appropriate leader.

    It offers automatic failover when a server goes down and it detects when the server comes back up.

    Load balancing is done using a simple round-robin on the list of servers.

    If a request to a server fails by an IOException due to a connection timeout or read timeout then the host is taken off the list of live servers and moved to a 'dead server list' and the request is resent to the next live server. This process is continued till it tries all the live servers. If at least one server is alive, the request succeeds, and if not it fails. 

     SolrClient lbHttpSolrClient = new LBHttpSolrClient("http://host1:8080/solr/", "http://host2:8080/solr", "http://host2:8080/solr");
 //or if you wish to pass the HttpClient do as follows
 httpClient httpClient = new HttpClient();
 SolrClient lbHttpSolrClient = new LBHttpSolrClient(httpClient, "http://host1:8080/solr/", "http://host2:8080/solr", "http://host2:8080/solr");
    This detects if a dead server comes alive automatically. The check is done in fixed intervals in a dedicated thread. This interval can be set using setAliveCheckInterval(int) , the default is set to one minute.

    When to use this?
    This can be used as a software load balancer when you do not wish to setup an external load balancer. Alternatives to this code are to use a dedicated hardware load balancer or using Apache httpd with mod_proxy_balancer as a load balancer. See Load balancing on Wikipedia

    Since:
    solr 1.4
    See Also:
    Serialized Form

    • Constructor Detail

      • LBHttpSolrClient

        @Deprecated
protected LBHttpSolrClient​(HttpSolrClient.Builder httpSolrClientBuilder,
                           org.apache.http.client.HttpClient httpClient,
                           String... solrServerUrl)
        Deprecated.
        use LBHttpSolrClient(Builder) instead, as it is a more extension/subclassing-friendly alternative
        The provided httpClient should use a multi-threaded connection manager

      • LBHttpSolrClient

        @Deprecated
protected LBHttpSolrClient​(org.apache.http.client.HttpClient httpClient,
                           ResponseParser parser,
                           String... solrServerUrl)
        Deprecated.
        use LBHttpSolrClient(Builder) instead, as it is a more extension/subclassing-friendly alternative
        The provided httpClient should use a multi-threaded connection manager

    • Method Detail

      • getQueryParams

        public Set<String> getQueryParams()

      • setQueryParams

        public void setQueryParams​(Set<String> queryParams)
        Expert Method.
        Parameters:
        queryParams - set of param keys to only send via the query string

      • addQueryParams

        public void addQueryParams​(String queryOnlyParam)

      • normalize

        public static String normalize​(String server)

      • request

        public LBHttpSolrClient.Rsp request​(LBHttpSolrClient.Req req)
                             throws SolrServerException,
                                    IOException
        Tries to query a live server from the list provided in Req. Servers in the dead pool are skipped. If a request fails due to an IOException, the server is moved to the dead pool for a certain period of time, or until a test request on that server succeeds. Servers are queried in the exact order given (except servers currently in the dead pool are skipped). If no live servers from the provided list remain to be tried, a number of previously skipped dead servers will be tried. Req.getNumDeadServersToTry() controls how many dead servers will be tried. If no live servers are found a SolrServerException is thrown.
        Parameters:
        req - contains both the request as well as the list of servers to query
        Returns:
        the result of the request
        Throws:
        IOException - If there is a low-level I/O error.
        SolrServerException

      • removeSolrServer

        public String removeSolrServer​(String server)

      • setSoTimeout

        @Deprecated
public void setSoTimeout​(int timeout)
        Deprecated.
        since 7.0 Use LBHttpSolrClient.Builder methods instead.
        set soTimeout (read timeout) on the underlying HttpConnectionManager. This is desirable for queries, but probably not for indexing.

      • close

        public void close()

      • request

        public NamedList<Object> request​(SolrRequest request,
                                 String collection)
                          throws SolrServerException,
                                 IOException
        Tries to query a live server. A SolrServerException is thrown if all servers are dead. If the request failed due to IOException then the live server is moved to dead pool and the request is retried on another live server. After live servers are exhausted, any servers previously marked as dead will be tried before failing the request.
        Specified by:
        request in class SolrClient
        Parameters:
        request - the SolrRequest.
        collection - the collection to execute the request against
        Returns:
        response
        Throws:
        IOException - If there is a low-level I/O error.
        SolrServerException - if there is an error on the server

      • setAliveCheckInterval

        public void setAliveCheckInterval​(int interval)
        LBHttpSolrServer keeps pinging the dead servers at fixed interval to find if it is alive. Use this to set that interval
        Parameters:
        interval - time in milliseconds

      • getHttpClient

        public org.apache.http.client.HttpClient getHttpClient()
        Return the HttpClient this instance uses.

      • setParser

        public void setParser​(ResponseParser parser)
        Changes the ResponseParser that will be used for the internal SolrServer objects.
        Parameters:
        parser - Default Response Parser chosen to parse the response if the parser were not specified as part of the request.
        See Also:
        SolrRequest.getResponseParser()

      • setRequestWriter

        public void setRequestWriter​(RequestWriter requestWriter)
        Changes the RequestWriter that will be used for the internal SolrServer objects.
        Parameters:
        requestWriter - Default RequestWriter, used to encode requests sent to the server.