Errors while installing unicorn gem on OS X
I was updating my bundle for a rails 3.1 app, when I run into the following errors.
Installing unicorn (4.2.0) with native extensions
Gem::Installer::ExtensionBuildError: ERROR: Failed to build gem native extension.
/opt/local/bin/ruby1.9 extconf.rb
checking for SIZEOF_OFF_T in ruby.h... *** extconf.rb failed ***
Could not create Makefile due to some reason, probably lack of
necessary libraries and/or headers. Check the mkmf.log file for more
details. You may need configuration options.
Provided configuration options:
--with-opt-dir
--with-opt-include
--without-opt-include=${opt-dir}/include
--with-opt-lib
--without-opt-lib=${opt-dir}/lib
--with-make-prog
--without-make-prog
--srcdir=.
--curdir
--ruby=/opt/local/bin/ruby1.9
/opt/local/lib/ruby1.9/1.9.1/mkmf.rb:381:in `try_do': The compiler failed to generate an executable file. (RuntimeError)
You have to install development tools first.
from /opt/local/lib/ruby1.9/1.9.1/mkmf.rb:491:in `block in try_compile'
from /opt/local/lib/ruby1.9/1.9.1/mkmf.rb:443:in `with_werror'
from /opt/local/lib/ruby1.9/1.9.1/mkmf.rb:491:in `try_compile'
from /opt/local/lib/ruby1.9/1.9.1/mkmf.rb:686:in `macro_defined?'
from /opt/local/lib/ruby1.9/1.9.1/mkmf.rb:822:in `block in have_macro'
from /opt/local/lib/ruby1.9/1.9.1/mkmf.rb:790:in `block in checking_for'
from /opt/local/lib/ruby1.9/1.9.1/mkmf.rb:284:in `block (2 levels) in postpone'
from /opt/local/lib/ruby1.9/1.9.1/mkmf.rb:254:in `open'
from /opt/local/lib/ruby1.9/1.9.1/mkmf.rb:284:in `block in postpone'
from /opt/local/lib/ruby1.9/1.9.1/mkmf.rb:254:in `open'
from /opt/local/lib/ruby1.9/1.9.1/mkmf.rb:280:in `postpone'
from /opt/local/lib/ruby1.9/1.9.1/mkmf.rb:789:in `checking_for'
from /opt/local/lib/ruby1.9/1.9.1/mkmf.rb:821:in `have_macro'
from extconf.rb:4:in `
Gem files will remain installed in /Users/tin/.bundler/tmp/34826/gems/unicorn-4.2.0 for inspection.
Results logged to /Users/tin/.bundler/tmp/34826/gems/unicorn-4.2.0/ext/unicorn_http/gem_make.out
An error occured while installing unicorn (4.2.0), and Bundler cannot continue.
Make sure that `gem install unicorn -v '4.2.0'` succeeds before bundling.
And the mkmf.log contain this, which was the clue I needed.
"/usr/bin/gcc-4.2 -o conftest -I/opt/local/include/ruby-1.9.1/x86_64-darwin10 -I/opt/local/include/ruby-1.9.1/ruby/backward -I/opt/local/include/ruby-1.9.1 -I. -I/opt/local/include -D_XOPEN_SOURCE -D_DARWIN_C_SOURCE -I/opt/local/include -pipe -O2 -arch x86_64 -fno-common conftest.c -L. -L/opt/local/lib -L/opt/local/lib -L. -L/opt/local/lib -arch x86_64 -L/usr/local/lib -lruby.1.9.1 -lpthread -ldl -lobjc "
i686-apple-darwin10-gcc-4.2.1: vfork: Operation timed out
checked program was:
/* begin */
1: #include "ruby.h"
2:
3: int main() {return 0;}
/* end */
Notice the vfork: Operation timed out line? It turns out that I was running out of system resources (VM) and gcc can’t fork. Ah, my poor 8GB i7 laptop…. 
Fix was simple, I shutdown Firefox and Chrome w/their gadzillion windows and tabs opened. Then retried “bundle update” again, and voila!
Documenting it here in case other people run into similar problem.
