# Branch for Testing Parallel Build Issue

**URL:** <https://www.ruby-forum.com/t/branch-for-testing-parallel-build-issue/231608>\
**Category:** GNU Radio\
**Created:** [August 18, 2014, 10:47pm UTC](https://www.ruby-forum.com/t/branch-for-testing-parallel-build-issue/231608 "2014-08-18T22:47:09Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![addis\_a](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/c4cdca/32.png) [@addis\_a](https://www.ruby-forum.com/u/addis_a)\
**Post date:** [August 18, 2014, 10:47pm UTC](https://www.ruby-forum.com/t/branch-for-testing-parallel-build-issue/231608/1 "2014-08-18T22:47:09Z")

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\< [https://github.com/jmcorgan/gnuradio/tree/fix-parallel-build](https://github.com/jmcorgan/gnuradio/tree/fix-parallel-build) \>

The goal of this branch is to fix the parallel build issue that’s been  
plaguing GNU Radio’s CMake build system pretty much since day 1. The  
shortest explanation of this fix is that CMake has a bug in it when  
handling multiple generated files in a single command. This bug has  
been known for years in various versions, and is on the back burner for  
them to fix as time allows someday. My fix is to explicitly spell out  
to CMake the dependencies and commands to execute in order, rather than  
trusting CMake to do it itself.

The issue manifests itself in the following way: After performing a  
“make -j#” to completion with #\>1, doing another “make” results in a  
small number of SWIG-generated .cxx files being recompiled. This issue  
happens more reliably with higher "#"s – about 25% of the time when  
using “-j8” on my Mac OS X box.

I encourage anybody interested to check out this branch and give it a  
test using “make -j” or “make -j8” or whatever works on your system with  
#\>1. In testing thus far, this change actually allows for -more-  
parallelism in builds than without it; and, it has thus far functioned  
flawlessly using CMake 2.6, 2.8, and 3.0.

If you do testing, feel free to reply to the group or email me directly  
with your successes or failures. Try touching headers (.h and .i) and  
sources to see if rebuilding happens correctly.

## Thanks in advance for any feedback on this change. - MLD

Michael D., OSX Programmer  
Ettus R. Technical Support  
Email: removed\_email\_address@domain.invalid  
Web: [http://www.ettus.com](http://www.ettus.com)

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**Author:** ![mdeering](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/278dde/32.png) [@mdeering](https://www.ruby-forum.com/u/mdeering)\
**Post date:** [August 19, 2014, 5:48pm UTC](https://www.ruby-forum.com/t/branch-for-testing-parallel-build-issue/231608/2 "2014-08-19T17:48:24Z")

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