ant-dev mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Steve Loughran <ste...@apache.org>
Subject Re: Parallel processing option for subant?
Date Wed, 12 Oct 2005 11:50:04 GMT
Jeffrey E Care wrote:
>>>This may sound naive, but honestly I would not expect many. 
>>>
>>>Ant already has the <parallel> task, which of course is running things 
> 
> in 
> 
>>>other threads; additionally in the WAS build tools we already have 
> 
> what is 
> 
>>>essentially the equivalent to a parallel subant, and it's working 
> 
> fine.
> 
>>>Would you expect a lot of threading-related errors from the Ant core 
>>>classes? If so what areas in particular are you worried about?
>>
>>I just worry that nothing has been written for thread safety, and 
>>generally that is bad news. I am not even sure that property read/write 
>>is atomic right now.
> 
> 
> Would that matter? All property reads/writes would be confined to the 
> thread there the project is being executed. The main problem I think would 
> be in the logger, but I've modified our custom logger to do thread 
> correlation & buffering; these changes should easily map to Ant's 
> DefaultLogger.

Input is another issue.

> 
> If there's a lot of general concern/opposition about this function I don't 
> want to take the time to develop a patch only to see it languish in 
> bugzilla or be outright rejected (which is why I wanted to discuss it here 
> first). Would it be appropriate to add this function and put a warning in 
> the manual that using the parallel execution could potentially be 
> dangerous?

to an extent <parallel> is the most prone to race conditions, as it is 
running stuff in the same project. a subant running in parallel is 
likely to share much less, just a FileUtils instance and maybe some 
references handed down.

> 
> The reason why I'm sort of pushing so hard for this function is that we've 
> already implemented something similar in the WAS build tools and it's 
> shaved 25-30% off of some of our builds with no adverse effects.
> 

I guess we can view that as a functional test :) What hardware were you 
running on? How many CPUs?

Maybe the thing to do would be to add lots of warnings around it, "use 
at your own risk", and note in the task writing guidelines about thread 
safety. A review of Project and some other core classes for possible 
race conditions

-steve

---------------------------------------------------------------------
To unsubscribe, e-mail: dev-unsubscribe@ant.apache.org
For additional commands, e-mail: dev-help@ant.apache.org


Mime
View raw message