HConnectionManager (Apache HBase 1.2.12 API)

java.lang.Object
- org.apache.hadoop.hbase.client.ConnectionFactory
- - org.apache.hadoop.hbase.client.HConnectionManager

Deprecated.
Please use ConnectionFactory instead
```
@InterfaceAudience.Public
@InterfaceStability.Evolving
@Deprecated
public class HConnectionManager
extends ConnectionFactory
```
A non-instantiable class that manages creation of HConnections.
The simplest way to use this class is by using createConnection(Configuration). This creates a new HConnection to the cluster that is managed by the caller. From this HConnection HTableInterface implementations are retrieved with HConnection.getTable(byte[]). Example:
```
 HConnection connection = HConnectionManager.createConnection(config);
 HTableInterface table = connection.getTable(TableName.valueOf("table1"));
 try {
   // Use the table as needed, for a single operation and a single thread
 } finally {
   table.close();
   connection.close();
 }
 
```
This class has a static Map of HConnection instances keyed by HConnectionKey; A HConnectionKey is identified by a set of Configuration properties. Invocations of getConnection(Configuration) that pass the same Configuration instance will return the same HConnection instance ONLY WHEN the set of properties are the same (i.e. if you change properties in your Configuration instance, such as RPC timeout, the codec used, HBase will create a new HConnection instance. For more details on how this is done see HConnectionKey).
Sharing HConnection instances is usually what you want; all clients of the HConnection instances share the HConnections' cache of Region locations rather than each having to discover for itself the location of meta, etc. But sharing connections makes clean up of HConnection instances a little awkward. Currently, clients cleanup by calling deleteConnection(Configuration). This will shutdown the zookeeper connection the HConnection was using and clean up all HConnection resources as well as stopping proxies to servers out on the cluster. Not running the cleanup will not end the world; it'll just stall the closeup some and spew some zookeeper connection failed messages into the log. Running the cleanup on a HConnection that is subsequently used by another will cause breakage so be careful running cleanup.
To create a HConnection that is not shared by others, you can set property "hbase.client.instance.id" to a unique value for your Configuration instance, like the following:
```
 conf.set("hbase.client.instance.id", "12345");
 HConnection connection = HConnectionManager.getConnection(conf);
 // Use the connection to your hearts' delight and then when done...
 conf.set("hbase.client.instance.id", "12345");
 HConnectionManager.deleteConnection(conf, true);
 
 
```
Cleanup used to be done inside in a shutdown hook. On startup we'd register a shutdown hook that called deleteAllConnections() on its way out but the order in which shutdown hooks run is not defined so were problematic for clients of HConnection that wanted to register their own shutdown hooks so we removed ours though this shifts the onus for cleanup to the client.

Field Summary

Fields
Modifier and Type Field and Description

static int MAX_CACHED_CONNECTION_INSTANCES
Deprecated.

static String RETRIES_BY_SERVER_KEY
Deprecated.

Fields
Modifier and Type	Field and Description
`static int`	`MAX_CACHED_CONNECTION_INSTANCES` Deprecated.
`static String`	`RETRIES_BY_SERVER_KEY` Deprecated.

Method Summary

Methods
Modifier and Type	Method and Description
`static HConnection`	`createConnection(org.apache.hadoop.conf.Configuration conf)` Deprecated.
`static HConnection`	`createConnection(org.apache.hadoop.conf.Configuration conf, ExecutorService pool)` Deprecated.
`static HConnection`	`createConnection(org.apache.hadoop.conf.Configuration conf, ExecutorService pool, User user)` Deprecated.
`static HConnection`	`createConnection(org.apache.hadoop.conf.Configuration conf, User user)` Deprecated.
`static void`	`deleteAllConnections()` Deprecated. kept for backward compatibility, but the behavior is broken. HBASE-8983
`static void`	`deleteAllConnections(boolean staleConnection)` Deprecated.
`static void`	`deleteConnection(org.apache.hadoop.conf.Configuration conf)` Deprecated.
`static void`	`deleteStaleConnection(HConnection connection)` Deprecated.
`static HConnection`	`getConnection(org.apache.hadoop.conf.Configuration conf)` Deprecated.

Methods inherited from class org.apache.hadoop.hbase.client.ConnectionFactory
createConnection

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Field Detail
  - RETRIES_BY_SERVER_KEY
```
@Deprecated
public static final String RETRIES_BY_SERVER_KEY
```
    Deprecated.
    
    See Also:
    Constant Field Values
  - MAX_CACHED_CONNECTION_INSTANCES
```
@Deprecated
public static final int MAX_CACHED_CONNECTION_INSTANCES
```
    Deprecated.
- Method Detail
  - getConnection
```
@Deprecated
public static HConnection getConnection(org.apache.hadoop.conf.Configuration conf)
                                 throws IOException
```
    Deprecated.
    
    Get the connection that goes with the passed conf configuration instance. If no current connection exists, method creates a new connection and keys it using connection-specific properties from the passed Configuration; see HConnectionKey.
    
    Parameters:
    conf - configuration
    
    Returns:
    HConnection object for conf
    
    Throws:
    
    ZooKeeperConnectionException
    
    IOException
  - createConnection
```
@Deprecated
public static HConnection createConnection(org.apache.hadoop.conf.Configuration conf)
                                    throws IOException
```
    Deprecated.
    Create a new HConnection instance using the passed conf instance.
    Note: This bypasses the usual HConnection life cycle management done by getConnection(Configuration). The caller is responsible for calling Connection.close() on the returned connection instance. This is the recommended way to create HConnections.
```
 HConnection connection = HConnectionManager.createConnection(conf);
 HTableInterface table = connection.getTable("mytable");
 try {
   table.get(...);
   ...
 } finally {
   table.close();
   connection.close();
 }
 
```
    Parameters:
    conf - configuration
    
    Returns:
    HConnection object for conf
    
    Throws:
    
    ZooKeeperConnectionException
    
    IOException
  - createConnection
```
@Deprecated
public static HConnection createConnection(org.apache.hadoop.conf.Configuration conf,
                                      ExecutorService pool)
                                    throws IOException
```
    Deprecated.
    Create a new HConnection instance using the passed conf instance.
    Note: This bypasses the usual HConnection life cycle management done by getConnection(Configuration). The caller is responsible for calling Connection.close() on the returned connection instance. This is the recommended way to create HConnections.
```
 ExecutorService pool = ...;
 HConnection connection = HConnectionManager.createConnection(conf, pool);
 HTableInterface table = connection.getTable("mytable");
 table.get(...);
 ...
 table.close();
 connection.close();
 
```
    Parameters:
    conf - configuration
    pool - the thread pool to use for batch operation in HTables used via this HConnection
    
    Returns:
    HConnection object for conf
    
    Throws:
    
    ZooKeeperConnectionException
    
    IOException
  - createConnection
```
@Deprecated
public static HConnection createConnection(org.apache.hadoop.conf.Configuration conf,
                                      User user)
                                    throws IOException
```
    Deprecated.
    Create a new HConnection instance using the passed conf instance.
    Note: This bypasses the usual HConnection life cycle management done by getConnection(Configuration). The caller is responsible for calling Connection.close() on the returned connection instance. This is the recommended way to create HConnections.
```
 ExecutorService pool = ...;
 HConnection connection = HConnectionManager.createConnection(conf, pool);
 HTableInterface table = connection.getTable("mytable");
 table.get(...);
 ...
 table.close();
 connection.close();
 
```
    Parameters:
    conf - configuration
    user - the user the connection is for
    
    Returns:
    HConnection object for conf
    
    Throws:
    
    ZooKeeperConnectionException
    
    IOException
  - createConnection
```
@Deprecated
public static HConnection createConnection(org.apache.hadoop.conf.Configuration conf,
                                      ExecutorService pool,
                                      User user)
                                    throws IOException
```
    Deprecated.
    Create a new HConnection instance using the passed conf instance.
    Note: This bypasses the usual HConnection life cycle management done by getConnection(Configuration). The caller is responsible for calling Connection.close() on the returned connection instance. This is the recommended way to create HConnections.
```
 ExecutorService pool = ...;
 HConnection connection = HConnectionManager.createConnection(conf, pool);
 HTableInterface table = connection.getTable("mytable");
 table.get(...);
 ...
 table.close();
 connection.close();
 
```
    Parameters:
    conf - configuration
    pool - the thread pool to use for batch operation in HTables used via this HConnection
    user - the user the connection is for
    
    Returns:
    HConnection object for conf
    
    Throws:
    
    ZooKeeperConnectionException
    
    IOException
  - deleteConnection
```
@Deprecated
public static void deleteConnection(org.apache.hadoop.conf.Configuration conf)
```
    Deprecated.
    
    Delete connection information for the instance specified by passed configuration. If there are no more references to the designated connection connection, this method will then close connection to the zookeeper ensemble and let go of all associated resources.
    
    Parameters:
    conf - configuration whose identity is used to find HConnection instance.
  - deleteStaleConnection
```
@Deprecated
public static void deleteStaleConnection(HConnection connection)
```
    Deprecated.
    
    Cleanup a known stale connection. This will then close connection to the zookeeper ensemble and let go of all resources.
    
    Parameters:
    connection -
  - deleteAllConnections
```
@Deprecated
public static void deleteAllConnections(boolean staleConnection)
```
    Deprecated.
    
    Delete information for all connections. Close or not the connection, depending on the staleConnection boolean and the ref count. By default, you should use it with staleConnection to true.
  - deleteAllConnections
```
@Deprecated
public static void deleteAllConnections()
```
    Deprecated. kept for backward compatibility, but the behavior is broken. HBASE-8983
    
    Delete information for all connections..

Class HConnectionManager

Field Summary

Method Summary

Methods inherited from class org.apache.hadoop.hbase.client.ConnectionFactory

Methods inherited from class java.lang.Object

Field Detail

RETRIES_BY_SERVER_KEY

MAX_CACHED_CONNECTION_INSTANCES

Method Detail

getConnection

createConnection

createConnection

createConnection

createConnection

deleteConnection

deleteStaleConnection

deleteAllConnections

deleteAllConnections