Yes , executed under heavy loads by n-threads. Is there anything I need to be worried about?
On Fri, Jul 22, 2011 at 12:17 PM, large data <[email protected]> wrote: > thanks ted.. > > Are there any best practices around usage of HTablePool? For a code > structure like this > > HTablePool pool = new HTablePool(); > String tableName="table"; > > public void log(query) throws Exception { > > HTable table = pool.getTable(Bytes.toBytes(tableName); > ... > ... > //done > pool.putTable(Bytes.toBytes(tableName); > > } > > executed under heavy loads by n-threads. Is there anything I need to be > worried about? > > On Thu, Jul 21, 2011 at 11:21 AM, Ted Yu <[email protected]> wrote: > > > Please reuse HTable instances through HTablePool. > > > > > > > > On Jul 21, 2011, at 10:08 AM, large data <[email protected]> wrote: > > > > > thanks Doug...so you saying something like this called from diff > threads > > in > > > a fairly loaded system would not be much of a concern? > > > > > > log(String something){ > > > HTable htable = new HTable(); > > > htable.incrementColumnValue(key,columnFamily,columnQualifier,1L); > > > } > > > > > > > > > On Thu, Jul 21, 2011 at 10:01 AM, Doug Meil > > > <[email protected]>wrote: > > > > > >> > > >> re: "Now creating an instance of an Htable is quite expensive on a > per > > >> thread basis." > > >> > > >> Connection/metadata is managed statically. Creating Htables instances > > >> isn't that heavyweight. > > >> > > >> > > >> > > >> > > >> > > >> On 7/21/11 11:30 AM, "large data" <[email protected]> wrote: > > >> > > >>> Thanks Doug! this is very informative. Now creating an instance of an > > >>> HTable > > >>> is quite expensive on a per thread basis. Reading through the docs I > > found > > >>> this > > >>> > > >> > > > http://hbase.apache.org/apidocs/index.html?org/apache/hadoop/hbase/client/ > > >>> HTablePool.html > > >>> > > >>> Are there any best practices using HTablePool? HTablePool > > >>> sounds analogous to DB connection pools to me but I am not sure how > > >>> HTablePool.get() would work under multithreaded environment. > > >>> > > >>> thanks > > >>> > > >>> > > >>> On Wed, Jul 20, 2011 at 6:28 PM, Doug Meil > > >>> <[email protected]>wrote: > > >>> > > >>>> > > >>>> Hi there- > > >>>> > > >>>> I think there are two subjects here: > > >>>> > > >>>> > > >>>> 1) the fact that HTable isn't thread-safe > > >>>> > > >>>> 2) how counters work > > >>>> > > >>>> Even if you are incrementing counters, you shouldn't be sharing > HTable > > >>>> instances across threads. > > >>>> > > >>>> Counters get updated atomically on the RS, not on the client. > > >>>> > > >>>> Counter behavior isn't in the Hbase book and it needs to be. I'll > add > > >>>> it > > >>>> to the list. > > >>>> > > >>>> > > >>>> On 7/20/11 7:44 PM, "large data" <[email protected]> wrote: > > >>>> > > >>>>> I have an HTable instance instantiated as part of a singleton > > service. > > >>>>> This > > >>>>> singleton service is called from different threads from different > > >>>> parts of > > >>>>> the app. Reading through the HTable docs suggests not to use single > > >>>> HTable > > >>>>> instance for updates, if it's true how can incrementColumnValue > > provide > > >>>>> thread safety? > > >>>>> > > >>>>> thanks > > >>>> > > >>>> > > >> > > >> > > > -- 陈加俊 项目经理 优讯时代（北京）网络技术有限公司 优讯网 www.uuwatch.com 地址：北京市海淀区上地信息路2号D栋412 电话：010-82895510 传真：010-82896636 手机：15110038983 电邮：*[email protected]*
