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From Ted Yu <yuzhih...@gmail.com>
Subject Re: connection.isMasterRunning()
Date Mon, 29 Mar 2010 21:35:17 GMT
https://issues.apache.org/jira/browse/HBASE-2391 has been filed.

We call HBaseAdmin.isMasterRunning() to see if client has connection with
HBase. If there is a working alternative, we'd love to use it.

Thanks J-D.

On Mon, Mar 29, 2010 at 2:25 PM, Jean-Daniel Cryans <jdcryans@apache.org>wrote:

> I think this method wasn't updated when we moved to Zookeeper (since
> in pre-0.20, dead master = dead cluster), also looking at when this is
> called, I only see it from HMerge and HBaseAdmin.isMasterRunning()...
> which in turn isn't called anywhere in the java code (I think we call
> it in the shell tho).
>
> So we should first consider if this method is useful at all, and if so
> then what would be the best fix. For example, if you run a HMerge
> while the master is down but the region servers are up, you're going
> to end up with something wrong since it expects hbase to be completely
> down.
>
> Can you open a jira to continue discussions there?
>
> Thx!
>
> J-D
>
> On Mon, Mar 29, 2010 at 2:01 PM, Ted Yu <yuzhihong@gmail.com> wrote:
> > Hi,
> > While going over TableServers.isMasterRunning() in HConnectionManager, I
> see
> > this:
> >    public boolean isMasterRunning() {
> >      if (this.master == null) {
> >        try {
> >          getMaster();
> >
> >        } catch (MasterNotRunningException e) {
> >          return false;
> >        }
> >      }
> >      return true;
> >    }
> > When isMasterRunning() is called the first time, if master is obtained
> > successfully, master field would contain reference to HMasterInterface.
> > Subsequent calls to isMasterRunning() wouldn't throw
> > MasterNotRunningException even if master server stops responding to
> clients.
> >
> > I think master.isMasterRunning() should be called if master isn't null.
> >
> > Regards
> >
>

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