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From Bharath Vissapragada <bhara...@cloudera.com>
Subject Re: What is proper way to make a hbase connection? using HTable (conf,tbl) or createConnection? Zookeeper session run out.
Date Mon, 24 Nov 2014 09:51:06 GMT
Yes thats correct. HTable is not thread-safe.

On Mon, Nov 24, 2014 at 2:55 PM, Liu, Ming (HPIT-GADSC) <ming.liu2@hp.com>
wrote:

> Thank you Bharath,
>
> This is a very helpful reply! I will share the connection between two
> threads. Simply put, HTable is not safe for multi-thread, is this true? In
> multi-threads, one must use HConnectionManager.
>
> Thanks,
> Ming
> -----Original Message-----
> From: Bharath Vissapragada [mailto:bharathv@cloudera.com]
> Sent: Monday, November 24, 2014 4:52 PM
> To: hbase-user
> Subject: Re: What is proper way to make a hbase connection? using HTable
> (conf,tbl) or createConnection? Zookeeper session run out.
>
> Hi Ming,
>
> HConnection connection = HConnectionManager.createConnection(conf);
> HTableInterface table = connection.getTable("mytable"); table.get(...); /
> table.put(...);
>
> Is the correct way to use. However
> HConnectionManager.createConnection(conf)  gives you a "shared"
> HConnection which you can reuse across multiple threads that get their own
> conn.getTable() and do their puts/gets.
>
> Thanks,
> Bharath
>
> On Mon, Nov 24, 2014 at 2:03 PM, Liu, Ming (HPIT-GADSC) <ming.liu2@hp.com>
> wrote:
>
> > Hello,
> >
> > I am using HBase 0.98.5. In example hbase client programs, some use
> > createConnection() and some use HTable() directly, I found they behave
> > different, I wrote two simple tests program using these two different
> > methods, each program will start two threads and do simple put.  and I
> > found:
> > One program will start only 1 zookeeper sessions shared in two threads
> > while another will start 2 zookeeper sessions. So I don't know why the
> > program using createConnection  will do more zookeeper requests than
> > simply use HTable. Is it possible to use createConnection in two
> > threads but share the same zookeeper session?
> >
> > Here is details:
> > Demo1 will make two zookeeper sessions, seems two HBase connections;
> > but
> > Demo2 will only make one zookeeper session. My real program is using
> > createConnection in multiple threads as in demo1, since I have a very
> > small zookeeper , it only allows 60 concurrent sessions, so my program
> > always fail when there are hundreds of threads started. But I saw if
> > using HTable directly, it will only consume 1 zookeeper session. But
> > it will change a lot in my current program, so I wish there is a way
> > to use createConnection and behave same as using HTable, is it possible?
> >
> > Source code:
> >
> > Demo1.java
> > class ClientThread extends Thread
> > {
> >         public static Configuration configuration;
> >         static {
> >                 configuration = HBaseConfiguration.create();
> >         }
> >         public void run()
> >         {
> >         try {
> >                 System.out.println("start insert data ......");
> >                 HConnection
> > con=HConnectionManager.createConnection(configuration);
> >                 HTable table = (HTable)con.getTable("hbase_table1");
> >                 Put put = new Put("1".getBytes());
> >                 put.add("c1".getBytes(), null, "baidu".getBytes());
> >                 put.add("c2".getBytes(), null, "http://www.baidu.com1
> > ".getBytes());
> >                 try {
> >                         table.put(put);
> >                 } catch (IOException e) {
> >                         e.printStackTrace();
> >                 }
> >                 System.out.println("end insert data ......");
> >         }
> >         catch  (Exception e) {
> >        }
> >
> >         }
> > }
> > public class demo1 {
> >
> >         public static void main(String[] args) throws Exception {
> >                 Thread t1=new ClientThread();
> >                 Thread t2=new ClientThread();
> >                 t1.start();
> >                 t2.start();
> >         }
> >
> > }
> >
> >
> > Demo2.java
> > class ClientThread1 extends Thread
> > {
> >         public static Configuration configuration;
> >         static {
> >                 configuration = HBaseConfiguration.create();
> >         }
> >         public void run()
> >         {
> >                 System.out.println("start insert data ......");
> >                 try {
> >                         HTableInterface table = new
> > HTable(configuration, "hbase_table1");
> >                         Put put = new Put("1".getBytes());
> >                         put.add("c1".getBytes(), null,
> "baidu".getBytes());
> >                         put.add("c2".getBytes(), null, "
> > http://www.baidu.com1".getBytes());
> >                         table.put(put);
> >                 } catch (Exception e) {
> >                         e.printStackTrace();
> >                 }
> >                 System.out.println("end insert data ......");
> >
> >         }
> >
> >
> > }
> > public class demo2 {
> >
> >         public static void main(String[] args) throws Exception {
> >                 Thread t1=new ClientThread1();
> >                 Thread t2=new ClientThread1();
> >                 t1.start();
> >                 t2.start();
> >         }
> > }
> >
> >
> >
> > This should be a very basic question, sorry, I really did some search
> > but cannot find any good explaination. Any help will be very appreciated.
> >
> > Thanks,
> > Ming
> >
>
>
>
> --
> Bharath Vissapragada
> <http://www.cloudera.com>
>



-- 
Bharath Vissapragada
<http://www.cloudera.com>

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