Re: connection.isMasterRunning()

[Al Lias <al...@gmx.de>]

Am 29.03.2010 23:35, schrieb Ted Yu:
> 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.
> 

Just to catch up on this....what is the recommended way to
programmatically check if Hbase is up (say on 0.20.4)?

Thx,

	Al

> ...
> On Mon, Mar 29, 2010 at 2:25 PM, Jean-Daniel Cryans <jd...@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 <yu...@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
>>>
>>
> 

Re: connection.isMasterRunning()

[Jean-Daniel Cryans <jd...@apache.org>]

Check if in Zookeeper the znode /hbase/master is there. You can easily
do this by using
org.apache.hadoop.hbase.zookeeper.ZooKeeperWrapper.readMasterAddressOrThrow().
This method isn't static, you have to create your own instance.

J-D

On Tue, May 11, 2010 at 5:38 AM, Al Lias <al...@gmx.de> wrote:
> Am 29.03.2010 23:35, schrieb Ted Yu:
>> 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.
>>
>
> Just to catch up on this....what is the recommended way to
> programmatically check if Hbase is up (say on 0.20.4)?
>
> Thx,
>
>        Al
>
>> ...
>> On Mon, Mar 29, 2010 at 2:25 PM, Jean-Daniel Cryans <jd...@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 <yu...@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
>>>>
>>>
>>
>
>