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From: Knute Johnson <nospam@knutejohnson.com>
Newsgroups: comp.lang.java.programmer
Subject: Re: single instance
Date: Wed, 16 Jan 2013 17:14:14 -0800
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On 1/16/2013 10:29 AM, Arne Vajhøj wrote:
> On 1/16/2013 1:51 AM, Roedy Green wrote:
>> On Sat, 05 Jan 2013 19:49:08 -0800, Knute Johnson
>> <nospam@knutejohnson.com> wrote, quoted or indirectly quoted someone
>> who said :
>>> The risk is, that in Windows anyway, where the system clock granularity
>>> is 17ms it is possible to start two copies of a program with a batch
>>
>> I have been studying Knute's code and Peter's commentary hoping to
>> come up with a canned package for ensuring single Instance.
>>
>> Using system.nanotime aught to help avoid granularity trouble.
>
> 1) It uses a smaller unit, but does not guarantee a smaller
>     granularity.

At least on my version of Windows, it was much finer.

> 2) It is only guaranteed to work within the same program as
>     the base is not fixed.
>
> 3) No matter how small a granularity, then it still just reduces
>     the risk of concurrency problems but does not eliminate the risk.
>
> Arne

It doesn't have to be perfect just good enough to stop what you want to 
stop.  For the application I have, I'm not worried about somebody 
starting two copies with a batch file only by clicking on an icon or 
typing into a command line.  For that it will be more than adequate.

-- 

Knute Johnson