[ET Trac] [Einstein Toolkit] #1465: Boost doesn't honor parallel build options

[Einstein Toolkit]

#1465: Boost doesn't honor parallel build options
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 Reporter:  knarf                  |       Owner:                     
     Type:  enhancement            |      Status:  new                
 Priority:  minor                  |   Milestone:                     
Component:  EinsteinToolkit thorn  |     Version:  development version
 Keywords:                         |  
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 ExternalLibraries/Boost doesn't honor parallel build options. This is
 because it doesn't use 'make' to build, but a tool called 'b2', which
 isn't using 'make's environment variables, nor is it capable to interact
 with the jobserver make provides. Manually parsing MAKEFLAGS inside the
 configure script of the thorn also doesn't work, as this doesn't contain
 the requested number of jobs, but only the fact that a parallel build was
 requested and a pointer to the jobserver. Manually interacting with this
 job server might be possible for gnu make, but is probably messy and
 highly likely not portable.

 However, building a huge package like Boost in parallel is something we
 have to achieve. On my workstation it reduces the time used for building
 Boost alone from about 500s to 60s.

 The only alternative that is easy enough to implement that I can see right
 now is to make it possible to pass a number of processes used for building
 to Cactus (in addition to passing it to make), and Boost using this
 variable for the parallel build. Simfactory should then also pass this to
 Cactus. One downside of this would be that if multiple libraries were to
 be built in parallel you might end up using almost twice as many jobs than
 specified. On the other hand, this doesn't seem to be the case right now
 and even if using twice as many might be better than many times too few.

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Ticket URL: <https://trac.einsteintoolkit.org/ticket/1465>
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