org.apache.solr.client.solrj.impl

Class LBHttpSolrClient

java.lang.Object

org.apache.solr.client.solrj.SolrClient

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

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	LBHttpSolrClient.Builder Constructs LBHttpSolrClient instances from provided configuration.
static class	LBHttpSolrClient.Req
static class	LBHttpSolrClient.Rsp
protected static class	LBHttpSolrClient.ServerWrapper

Field Summary

Fields

Modifier and Type	Field and Description
protected Map<String,LBHttpSolrClient.ServerWrapper>	zombieServers

Constructor Summary

Constructors

Constructor and Description
LBHttpSolrClient(org.apache.http.client.HttpClient httpClient, ResponseParser parser, String... solrServerUrl) Deprecated. use LBHttpSolrClient.Builder instead. This will soon be a protected method and will only be available for use in implementing subclasses.
LBHttpSolrClient(org.apache.http.client.HttpClient httpClient, String... solrServerUrl) Deprecated. use LBHttpSolrClient.Builder instead.
LBHttpSolrClient(String... solrServerUrls) Deprecated. use LBHttpSolrClient.Builder instead.

Method Summary

Modifier and Type	Method and Description
void	addQueryParams(String queryOnlyParam)
void	addSolrServer(String server)
protected Exception	addZombie(HttpSolrClient server, Exception e)
void	close()
protected Exception	doRequest(HttpSolrClient client, LBHttpSolrClient.Req req, LBHttpSolrClient.Rsp rsp, boolean isUpdate, boolean isZombie, String zombieKey)
protected void	finalize()
org.apache.http.client.HttpClient	getHttpClient() Return the HttpClient this instance uses.
ResponseParser	getParser()
Set<String>	getQueryParams()
RequestWriter	getRequestWriter()
protected HttpSolrClient	makeSolrClient(String server)
static String	normalize(String server)
String	removeSolrServer(String server)
LBHttpSolrClient.Rsp	request(LBHttpSolrClient.Req req) Tries to query a live server from the list provided in Req.
NamedList<Object>	request(SolrRequest request, String collection) 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) Changes the ResponseParser that will be used for the internal SolrServer objects.
void	setQueryParams(Set<String> queryParams) Expert Method.
void	setRequestWriter(RequestWriter requestWriter) Changes the RequestWriter that will be used for the internal SolrServer objects.
void	setSoTimeout(int timeout) set soTimeout (read timeout) on the underlying HttpConnectionManager.

Methods inherited from class org.apache.solr.client.solrj.SolrClient

add, add, add, add, add, add, add, add, add, add, addBean, addBean, addBean, addBean, addBeans, addBeans, addBeans, addBeans, addBeans, addBeans, commit, commit, commit, commit, commit, commit, deleteById, deleteById, deleteById, deleteById, deleteById, deleteById, deleteById, deleteById, deleteByQuery, deleteByQuery, deleteByQuery, deleteByQuery, getBinder, getById, getById, getById, getById, getById, getById, getById, getById, optimize, optimize, optimize, optimize, optimize, optimize, ping, query, query, query, query, queryAndStreamResponse, queryAndStreamResponse, request, rollback, 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,LBHttpSolrClient.ServerWrapper> zombieServers

Constructor Detail

LBHttpSolrClient

@Deprecated
public LBHttpSolrClient(String... solrServerUrls)
                             throws MalformedURLException

Deprecated. use LBHttpSolrClient.Builder instead.

Throws:

MalformedURLException

LBHttpSolrClient

@Deprecated
public LBHttpSolrClient(org.apache.http.client.HttpClient httpClient,
                                    String... solrServerUrl)

Deprecated. use LBHttpSolrClient.Builder instead.

The provided httpClient should use a multi-threaded connection manager

LBHttpSolrClient

@Deprecated
public LBHttpSolrClient(org.apache.http.client.HttpClient httpClient,
                                    ResponseParser parser,
                                    String... solrServerUrl)

Deprecated. use LBHttpSolrClient.Builder instead. This will soon be a protected method and will only be available for use in implementing subclasses.

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)

makeSolrClient

protected HttpSolrClient makeSolrClient(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

addZombie

protected Exception addZombie(HttpSolrClient server,
                              Exception e)

doRequest

protected Exception doRequest(HttpSolrClient client,
                              LBHttpSolrClient.Req req,
                              LBHttpSolrClient.Rsp rsp,
                              boolean isUpdate,
                              boolean isZombie,
                              String zombieKey)
                       throws SolrServerException,
                              IOException

Throws:

SolrServerException

IOException

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.

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.

getParser

public ResponseParser getParser()

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.

getRequestWriter

public RequestWriter getRequestWriter()

finalize

protected void finalize()
                 throws Throwable

Overrides:

finalize in class Object

Throws:

Throwable