[Dev] Preventing user from running multiple instances

[Morgen Sagen]

Excellent, Andi.  Does anyone have an objection to me making 
exclusive-access the default for Chandler?

On Mar 2, 2005, at 11:26 AM, Andi Vajda wrote:

>
>> For various reasons we don't want the user to be able to run multiple 
>> instances of Chandler against the same repository.  For example, if 
>> you fire up two instances at the same time, one of them will complain 
>> that //Schema already exists, and there are other places where things 
>> don't quite work.  So I was wondering if anyone had an idea for a 
>> cross-platform way to prevent multiple concurrent instances accessing 
>> a repository.  Chandler could look for and create a lock file next to 
>> the repository directory, and place its process ID in there, thereby 
>> allowing it to detect whether an existing lock file is obsolete 
>> because a previous instance died without removing it.  (Does Windows 
>> have the notion of PID?)  This method leaves the repository itself 
>> out of it -- purely an application level function.  Or we could get 
>> the repository involved and have it keep track of which process has 
>> it open, and the application layer asks the repository.  I guess I 
>> would lean toward the former method.
>>
>> I'm sure there must be some python module that does this already, in 
>> a cross-platform way...
>
> This is an old problem that I fixed a few months ago. If you don't 
> want multiple Chandlers to run concurrently, start the first one with 
> -x or --exclusive.
>
> Andi..
>
>>
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