org.apache.solr.client.solrj.impl
Class LBHttpSolrServer

java.lang.Object
  extended by org.apache.solr.client.solrj.SolrServer
      extended by org.apache.solr.client.solrj.impl.LBHttpSolrServer
All Implemented Interfaces:
Serializable

public class LBHttpSolrServer
extends SolrServer

LBHttpSolrServer or "LoadBalanced HttpSolrServer" is a load balancing wrapper around HttpSolrServer. This is useful when you have multiple SolrServers 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, this class may be used for updates since updates will be forwarded to the appropriate leader. Also see the wiki page.

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.

 SolrServer lbHttpSolrServer = new LBHttpSolrServer("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();
 SolrServer lbHttpSolrServer = new LBHttpSolrServer(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

Nested Class Summary
static class LBHttpSolrServer.Req
           
static class LBHttpSolrServer.Rsp
           
protected static class LBHttpSolrServer.ServerWrapper
           
 
Field Summary
protected  Map<String,LBHttpSolrServer.ServerWrapper> zombieServers
           
 
Constructor Summary
LBHttpSolrServer(org.apache.http.client.HttpClient httpClient, ResponseParser parser, String... solrServerUrl)
          The provided httpClient should use a multi-threaded connection manager
LBHttpSolrServer(org.apache.http.client.HttpClient httpClient, String... solrServerUrl)
          The provided httpClient should use a multi-threaded connection manager
LBHttpSolrServer(String... solrServerUrls)
           
 
Method Summary
 void addSolrServer(String server)
           
protected  Exception addZombie(HttpSolrServer server, Exception e)
           
protected  void finalize()
           
 org.apache.http.client.HttpClient getHttpClient()
           
 ResponseParser getParser()
           
protected  HttpSolrServer makeServer(String server)
           
static String normalize(String server)
           
 String removeSolrServer(String server)
           
 LBHttpSolrServer.Rsp request(LBHttpSolrServer.Req req)
          Tries to query a live server from the list provided in Req.
 NamedList<Object> request(SolrRequest request)
          Tries to query a live server.
 void setAliveCheckInterval(int interval)
          LBHttpSolrServer keeps pinging the dead servers at fixed interval to find if it is alive.
 void setConnectionTimeout(int timeout)
           
 void setParser(ResponseParser parser)
           
 void setRequestWriter(RequestWriter requestWriter)
           
 void setSoTimeout(int timeout)
          set soTimeout (read timeout) on the underlying HttpConnectionManager.
 void shutdown()
          Release allocated resources.
 
Methods inherited from class org.apache.solr.client.solrj.SolrServer
add, add, add, add, addBean, addBean, addBeans, addBeans, commit, commit, commit, deleteById, deleteById, deleteById, deleteById, deleteByQuery, deleteByQuery, getBinder, optimize, optimize, optimize, ping, query, query, queryAndStreamResponse, rollback
 
Methods inherited from class java.lang.Object
clone, equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Field Detail

zombieServers

protected final Map<String,LBHttpSolrServer.ServerWrapper> zombieServers
Constructor Detail

LBHttpSolrServer

public LBHttpSolrServer(String... solrServerUrls)
                 throws MalformedURLException
Throws:
MalformedURLException

LBHttpSolrServer

public LBHttpSolrServer(org.apache.http.client.HttpClient httpClient,
                        String... solrServerUrl)
                 throws MalformedURLException
The provided httpClient should use a multi-threaded connection manager

Throws:
MalformedURLException

LBHttpSolrServer

public LBHttpSolrServer(org.apache.http.client.HttpClient httpClient,
                        ResponseParser parser,
                        String... solrServerUrl)
                 throws MalformedURLException
The provided httpClient should use a multi-threaded connection manager

Throws:
MalformedURLException
Method Detail

normalize

public static String normalize(String server)

makeServer

protected HttpSolrServer makeServer(String server)
                             throws MalformedURLException
Throws:
MalformedURLException

request

public LBHttpSolrServer.Rsp request(LBHttpSolrServer.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

addZombie

protected Exception addZombie(HttpSolrServer server,
                              Exception e)

addSolrServer

public void addSolrServer(String server)
                   throws MalformedURLException
Throws:
MalformedURLException

removeSolrServer

public String removeSolrServer(String server)

setConnectionTimeout

public void setConnectionTimeout(int timeout)

setSoTimeout

public void setSoTimeout(int timeout)
set soTimeout (read timeout) on the underlying HttpConnectionManager. This is desirable for queries, but probably not for indexing.


shutdown

public void shutdown()
Description copied from class: SolrServer
Release allocated resources.

Specified by:
shutdown in class SolrServer

request

public NamedList<Object> request(SolrRequest request)
                          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 SolrServer
Parameters:
request - the SolrRequest.
Returns:
response
Throws:
IOException - If there is a low-level I/O error.
SolrServerException

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()

getParser

public ResponseParser getParser()

setParser

public void setParser(ResponseParser parser)

setRequestWriter

public void setRequestWriter(RequestWriter requestWriter)

finalize

protected void finalize()
                 throws Throwable
Overrides:
finalize in class Object
Throws:
Throwable


Copyright © 2000-2013 Apache Software Foundation. All Rights Reserved.