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From Lars George <lars.geo...@gmail.com>
Subject Re: Canary Test Tool and write sniffing
Date Sun, 05 Feb 2017 10:25:53 GMT
The next example is wrong too, claiming to show 60 secs, while it
shows 600 secs (the default value as well).

The question is still, what is a good value for intervals? Anyone here
that uses the Canary that would like to chime in?

On Sat, Feb 4, 2017 at 5:40 PM, Ted Yu <yuzhihong@gmail.com> wrote:
> Brief search on HBASE-4393 didn't reveal why the interval was shortened.
>
> If you read the first paragraph of:
> http://hbase.apache.org/book.html#_run_canary_test_as_daemon_mode
>
> possibly the reasoning was that canary would exit upon seeing some error
> (the first time).
>
> BTW There was a mismatch in the description for this command: (5 seconds
> vs. 50000 milliseconds)
>
> ${HBASE_HOME}/bin/hbase canary -daemon -interval 50000 -f false
>
>
> On Sat, Feb 4, 2017 at 8:21 AM, Lars George <lars.george@gmail.com> wrote:
>
>> Oh right, Ted. An earlier patch attached to the JIRA had 60 secs, the
>> last one has 6 secs. Am I reading this right? It hands 6000 into the
>> Thread.sleep() call, which takes millisecs. So that makes 6 secs
>> between checks, which seems super short, no? I might just dull here.
>>
>> On Sat, Feb 4, 2017 at 5:00 PM, Ted Yu <yuzhihong@gmail.com> wrote:
>> > For the default interval , if you were looking at:
>> >
>> >   private static final long DEFAULT_INTERVAL = 6000;
>> >
>> > The above was from:
>> >
>> >     HBASE-4393 Implement a canary monitoring program
>> >
>> > which was integrated on Tue Apr 24 07:20:16 2012
>> >
>> > FYI
>> >
>> > On Sat, Feb 4, 2017 at 4:06 AM, Lars George <lars.george@gmail.com>
>> wrote:
>> >
>> >> Also, the default interval used to be 60 secs, but is now 6 secs. Does
>> >> that make sense? Seems awfully short for a default, assuming you have
>> >> many regions or servers.
>> >>
>> >> On Sat, Feb 4, 2017 at 11:54 AM, Lars George <lars.george@gmail.com>
>> >> wrote:
>> >> > Hi,
>> >> >
>> >> > Looking at the Canary tool, it tries to ensure that all canary test
>> >> > table regions are spread across all region servers. If that is not
the
>> >> > case, it calls:
>> >> >
>> >> > if (numberOfCoveredServers < numberOfServers) {
>> >> >   admin.balancer();
>> >> > }
>> >> >
>> >> > I doubt this will help with the StochasticLoadBalancer, which is known
>> >> > to consider per-table balancing as one of many factors. In practice,
>> >> > the SLB will most likely _not_ distribute the canary regions
>> >> > sufficiently, leaving gap in the check. Switching on the per-table
>> >> > option is discouraged against to let it do its thing.
>> >> >
>> >> > Just pointing it out for vetting.
>> >> >
>> >> > Lars
>> >>
>>

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