[Scons-users] [Scons-dev] Default number of jobs

[Kyle J Strand]

I agree with all of Marc's points, and I'd also like to add that when 
using multiple jobs, Python sometimes crashes (
http://scons.tigris.org/ds/viewMessage.do?dsForumId=1272&viewType=browseAll&dsMessageId=954632#messagefocus
), but I've never observed this with only a single job. So -j1 appears to 
be not only more consistent, but safer.

-----------------------------------------------------------------------
Kyle Strand, Software Intern
Beckman Coulter, Inc., Life Sciences Division
4862 Innovation Drive, Fort Collins, Colorado, 80525
(970) 204-7036

scons-users-bounces at scons.org wrote on 07/30/2012 08:25:30 AM:


> Marc Branchaud <marcnarc at xiplink.com> 

> Sent by: scons-users-bounces at scons.org

> 

> 07/30/2012 08:25 AM

> 

> Please respond to

> SCons users mailing list <scons-users at scons.org>

> 

> To

> 

> SCons users mailing list <scons-users at scons.org>

> 

> cc

> 

> SCons developer list <scons-dev at scons.org>

> 

> Subject

> 

> Re: [Scons-users] [Scons-dev] Default number of jobs

> 

> Please don't change the default number of jobs.

> 

> For one thing, not all builds benefit from parallelism.  Ours currently 

> doesn't -- the disk cache gets overwhelmed, even with just a small -j 

> value on a 16-core 32GB machine.  What's more, the optimal level of 

> parallelism (best number of jobs/core) differs from project to project. 

>   Finding the sweet spot is generally a matter of trial, tuning, and 

error.

> 

> More importantly, it can be quite difficult to diagnose problems in 

> parallelized builds, especially since output from simultaneous commands 

> is jumbled together.  Parallel failures of simultaneous commands are 

> especially confusing.

> 

> When developing a build, it's best if your tools don't assume they can 

> do surprising things.  Parallelism is one such surprising thing.  Using 

> an explicit flag to turn it on is a good way for the user to tell the 

> tool that she's ready for some possible weirdness.

> 

>       M.

> _______________________________________________

> Scons-users mailing list

> Scons-users at scons.org

> http://four.pairlist.net/mailman/listinfo/scons-users


The server  made the following annotations                           

---------------------------------------------------------------------------------

This message contains information that may be privileged or confidential and is the property of Beckman Coulter, Inc.  It is intended only for the person to whom it is addressed.  If you are not the intended recipient, you are not authorized to read, print, retain, copy, disseminate, distribute or use this message or any part thereof.  If you receive this message in error, please notify the sender immediately and delete all copies of this message.

---------------------------------------------------------------------------------

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://four.pairlist.net/pipermail/scons-users/attachments/20120730/08ac0689/attachment.htm>