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:bhara...@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.l...@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>
