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From Rakesh R <rake...@huawei.com>
Subject RE: Thread handling
Date Tue, 01 Apr 2014 04:03:02 GMT
>>> This is how I handle the critical threads in my client apps that use Zookeeper.
 
>>> Keep a reference to the thread and periodically make sure it's still alive and
well - respawn it if it is not.

Thanks Greg for the inputs. Please see ZK-1907, I've included an initial proposal patch to
kick start the discussions. 
Another approach is simply shutdown if a critical thread dies, so the monitoring tool can
easily detect and take necessary actions. The proposed patch is based on this approach.

-Rakesh

-----Original Message-----
From: Asta, Greg [mailto:greg.asta@omnigon.com] 
Sent: 31 March 2014 23:24
To: user@zookeeper.apache.org; dev@zookeeper.apache.org
Subject: RE: Thread handling

" If we have a 'DeathWatcher 'or some other mechanism in place to monitor all the critical
threads. It can take a decision like - bring down the process if required, or shutdown the
quorumpeer and go for LE again etc.
Now the monitoring or management tool will knows about the situation and can act upon.

Appreciate any thoughts ?"

This is how I handle the critical threads in my client apps that use Zookeeper.  Keep a reference
to the thread and periodically make sure it's still alive and well - respawn it if it is not.

Thanks,
Greg


-----Original Message-----
From: Rakesh R [mailto:rakeshr@huawei.com] 
Sent: Thursday, March 27, 2014 10:39 AM
To: dev@zookeeper.apache.org; user@zookeeper.apache.org
Subject: Thread handling

Hi All,

Server has many critical threads running and co-ordinating each other like  RequestProcessor
chains et. When going through each threads, most of them having the similar structure like:

public void run() {
        try {
              while(running)
                   // processing logic
              }
        } catch (InterruptedException e) {
            LOG.error("Unexpected interruption", e);
        } catch (RequestProcessorException e) {
            LOG.error("Unexpected exception", e);
        } catch (Exception e) {
            LOG.error("Unexpected exception", e);
        }
        LOG.info("...exited loop!");
}

I feel, we could improve our threads  in our system. From the design I could see, there could
be a chance of silently leaving the thread in case of any exception(abnormal or any functional
issue too) If this happens in the production, the server would get hanged forever and will
not be able to deliver its role.

If we have a 'DeathWatcher 'or some other mechanism in place to monitor all the critical threads.
It can take a decision like - bring down the process if required, or shutdown the quorumpeer
and go for LE again etc.
Now the monitoring or management tool will knows about the situation and can act upon.

Appreciate any thoughts ?

Thanks in advance,
Rakesh R

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