Hi, Ted, I am not sure. I am a C programmer, only know a very little java. It seems to me that the two coprocessors have to 'extends' from two different base classes for Endpoint and Observer. Java seems not be able to do this. I am just trying to study coprocessor, there is no solid production requirement to do this sharing thing. Coprocessor was introduced from 0.92, and no one need this before, so I am thinking this is not something important. Thanks always for your help! You are very kind to answer all my questions in this maillist :-) I will try to read the getSharedData code to further understand and feedback here if I can have some more findings or any other good method to shared data in a simple way.
Thanks, Ming -----Original Message----- From: Ted Yu [mailto:[email protected]] Sent: Thursday, April 16, 2015 5:16 AM To: [email protected] Subject: Re: how to use RegionCoprocessorEnvironment getSharedData() to share data among coprocessors? Can you implement the Observer coprocessor and the Endpoint coprocessor in one class ? Cheers On Wed, Apr 15, 2015 at 9:00 AM, Liu, Ming (HPIT-GADSC) <[email protected]> wrote: > Thank you Ted, > > I am using 0.98.11. I do read the first example, but I don't find the > second one before, I will try to read it, but it seems too complex for > me > :-) > I read from > http://hadoop-hbase.blogspot.com/2012/10/coprocessor-access-to-hbase-i > nternals.html That : "This shared data is per coprocessor class and > per regionserver." > So it means to me that hbase cannot share between two different > coprocessors like an endpoint and an observer by using this > sharedData, since there are two different classes in my case. I use > Zookeeper to share data for now, but I was told not to depend on > ZooKeeper too much, no idea why. Is there any other good way I can use > to share data among different coprocessors? > > Thanks, > Ming > -----Original Message----- > From: Ted Yu [mailto:[email protected]] > Sent: Wednesday, April 15, 2015 8:25 PM > To: [email protected] > Subject: Re: how to use RegionCoprocessorEnvironment getSharedData() > to share data among coprocessors? > > Which hbase release are you using ? > > Please take a look at the following tests for example of using > getSharedData() : > > > hbase-examples/src/main/java/org/apache/hadoop/hbase/coprocessor/examp > le/ZooKeeperScanPolicyObserver.java > > hbase-server/src/test/java/org/apache/hadoop/hbase/coprocessor/TestCop > rocessorInterface.java > > Cheers > > On Tue, Apr 14, 2015 at 10:35 PM, Liu, Ming (HPIT-GADSC) > <[email protected] > > > wrote: > > > Hi, all, > > > > I am trying to learn how to share data between two coprocessors. I > > have one Observer coprocessor and one Endpoint coprocessor. In the > > observer, it overload the prePut/preDelete to maintain a counter. > > And I want the Endpoint coprocessor to read that counter and return > > to client caller. So I want to use the getSharedData() method in > > RegionCoprocessorEnvironment, but I cannot make it work. Could > > anybody > help me here? > > > > In the Observer Coprocessor : > > During start(), create the shared object "counter": > > ----------------------------------------------------------------- > > public void start(CoprocessorEnvironment envi) throws IOException { > > Env.getSharedData().put("counter", new Long(0) ); //create the > > counter > > ----------------------------------------------------------------- > > > > In the Endpoint coprocessor: > > During start(), try to read the shared "counter" , but failed. > > ------------------------------------------------------------------ > > public void start(CoprocessorEnvironment envi) throws IOException { > > LOG.info("The size of sharedData map is: " + > > envi.getSharedData().size() ); //try to get the counter > > ------------------------------------------------------------------ > > Here it print 0, if I use > > evni.getSharedData().containsKey("counter"), > > it will return false. > > > > When creating table, I call addCoprocessor() method to add Observer > > first, then Endpoint coprocessor. I confirmed that by checking the > > hbase log file message. I only have one region for that table during > > the run. I confirmed by hbase shell status 'detailed' command. > > > > There is not much example I can find about how to use > > getSharedData(), could someone help me here? What is missing in my > > simple code? Thanks very much in advance! > > > > Thanks, > > Ming > > >
