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From: Henrik Nordvik <henrikno@gmail.com>
Date: Wed, 28 Aug 2013 16:44:55 +0200
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 <CAH3vNzPSd9J1KNZnh9iL=A3Gt5nTcfbEyN8n=fqcwK3KL_hgNg@mail.gmail.com>
Subject: LeaderSelector Executor
To: user@curator.incubator.apache.org
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Hi,

The LeaderSelector has a constructor which takes in ThreadFactory and
Executor as parameters. The "default" constructor uses
MoreExecutors.sameThreadExecutor().
I tried using my own ThreadPool with multiple threads, because I thought
that was they way of using multiple leaders.
When I did that, to my surprise, it started multiple leaders per path.
After reading the code it makes sense, it only guarantees that you are the
leader when submitting the thread to the executor.

It seems to me like using anything other than sameThreadExecutor makes
little sense.
When would you want to use it?


Example snippet:
    LeaderSelectorListener listener = new MyLeaderSelectorListener("1");
    ExecutorService executorPool = Executors.newFixedThreadPool(20);
    LeaderSelector leaderSelector = new LeaderSelector(client, path,
threadFactory, executorPool, listener);
    leaderSelector.autoRequeue();
    leaderSelector.start();
    // MyLeaderSelectorListener.takeLeadership is called multiple times
here, even though it is in a sleep-loop.


--
Henrik Nordvik

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<div dir=3D"ltr"><div><div><div>Hi,<br><br></div>The LeaderSelector has a c=
onstructor which takes in ThreadFactory and Executor as parameters. The &qu=
ot;default&quot; constructor uses MoreExecutors.sameThreadExecutor().<br></=
div>

I tried using my own ThreadPool with multiple threads, because I thought th=
at was they way of using multiple leaders. <br>When I did that, to my surpr=
ise, it started multiple leaders per path. After reading the code it makes =
sense, it only guarantees that you are the leader when submitting the threa=
d to the executor.<br>

<br>It seems to me like using anything other than sameThreadExecutor makes =
little sense.<br></div>When would you want to use it?<br><div><br><br></div=
><div>Example snippet:<br>=A0=A0=A0 LeaderSelectorListener listener =3D new=
 MyLeaderSelectorListener(&quot;1&quot;);<br>

=A0=A0=A0 ExecutorService executorPool =3D Executors.newFixedThreadPool(20)=
;<br>=A0=A0=A0 LeaderSelector leaderSelector =3D new LeaderSelector(client,=
 path, threadFactory, executorPool, listener);<br>=A0=A0=A0 leaderSelector.=
autoRequeue();<br>

=A0=A0=A0 leaderSelector.start();<br></div><div>=A0=A0=A0 // MyLeaderSelect=
orListener.takeLeadership is called multiple times here, even though it is =
in a sleep-loop.<br></div><div><br></div><div><div><div><br clear=3D"all"><=
div><div>
--<br>
Henrik Nordvik</div>
</div></div></div></div></div>

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