is autotools configure script multi-threaded safe?





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In a typical configure script generated by autotools, you have this kind of fragment:



eval "$ac_cpp conftest.$ac_ext") 2>&5 |
tr -d 'r' |
$SED -n -e "/^boost_lib_version = /{s///;s/"//g;p;q;}" >conftest.i 2>&1


This is somewhat complicated, but what matters for my question, is roughly:



g++ -E conftest.cpp > conftest.i 2>&1


Now, this is not multi-threaded safe is it?



I have myself seen a failure, where a Make process with -j option spawning multiple threads, one of the threads put out on standard-error some junk output, and another thread, running the configure script above, would put the errors from the first thread, into conftest.i. I guess this is because they share stream 2 (standard error), inherited from the parent process.



Who's at fault:




  1. Do autotools that generate the configure script, have a bug because they generate code that is not multi-threaded safe? But that is strange that such a simple bug would be present in such a mature software.


  2. Does the build script that uses the makefile that uses configure have a bug, in that it uses make with -jn option? But that is also strange, because many makefiles use configure scripts and it would be unreasonable to require all of them to be slow and not use -jn.



The failure above is real, I have seen it. I think I understand the mechanism of the failure. What I am confused about, is who has the bug?










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    0















    In a typical configure script generated by autotools, you have this kind of fragment:



    eval "$ac_cpp conftest.$ac_ext") 2>&5 |
    tr -d 'r' |
    $SED -n -e "/^boost_lib_version = /{s///;s/"//g;p;q;}" >conftest.i 2>&1


    This is somewhat complicated, but what matters for my question, is roughly:



    g++ -E conftest.cpp > conftest.i 2>&1


    Now, this is not multi-threaded safe is it?



    I have myself seen a failure, where a Make process with -j option spawning multiple threads, one of the threads put out on standard-error some junk output, and another thread, running the configure script above, would put the errors from the first thread, into conftest.i. I guess this is because they share stream 2 (standard error), inherited from the parent process.



    Who's at fault:




    1. Do autotools that generate the configure script, have a bug because they generate code that is not multi-threaded safe? But that is strange that such a simple bug would be present in such a mature software.


    2. Does the build script that uses the makefile that uses configure have a bug, in that it uses make with -jn option? But that is also strange, because many makefiles use configure scripts and it would be unreasonable to require all of them to be slow and not use -jn.



    The failure above is real, I have seen it. I think I understand the mechanism of the failure. What I am confused about, is who has the bug?










    share|improve this question



























      0












      0








      0








      In a typical configure script generated by autotools, you have this kind of fragment:



      eval "$ac_cpp conftest.$ac_ext") 2>&5 |
      tr -d 'r' |
      $SED -n -e "/^boost_lib_version = /{s///;s/"//g;p;q;}" >conftest.i 2>&1


      This is somewhat complicated, but what matters for my question, is roughly:



      g++ -E conftest.cpp > conftest.i 2>&1


      Now, this is not multi-threaded safe is it?



      I have myself seen a failure, where a Make process with -j option spawning multiple threads, one of the threads put out on standard-error some junk output, and another thread, running the configure script above, would put the errors from the first thread, into conftest.i. I guess this is because they share stream 2 (standard error), inherited from the parent process.



      Who's at fault:




      1. Do autotools that generate the configure script, have a bug because they generate code that is not multi-threaded safe? But that is strange that such a simple bug would be present in such a mature software.


      2. Does the build script that uses the makefile that uses configure have a bug, in that it uses make with -jn option? But that is also strange, because many makefiles use configure scripts and it would be unreasonable to require all of them to be slow and not use -jn.



      The failure above is real, I have seen it. I think I understand the mechanism of the failure. What I am confused about, is who has the bug?










      share|improve this question
















      In a typical configure script generated by autotools, you have this kind of fragment:



      eval "$ac_cpp conftest.$ac_ext") 2>&5 |
      tr -d 'r' |
      $SED -n -e "/^boost_lib_version = /{s///;s/"//g;p;q;}" >conftest.i 2>&1


      This is somewhat complicated, but what matters for my question, is roughly:



      g++ -E conftest.cpp > conftest.i 2>&1


      Now, this is not multi-threaded safe is it?



      I have myself seen a failure, where a Make process with -j option spawning multiple threads, one of the threads put out on standard-error some junk output, and another thread, running the configure script above, would put the errors from the first thread, into conftest.i. I guess this is because they share stream 2 (standard error), inherited from the parent process.



      Who's at fault:




      1. Do autotools that generate the configure script, have a bug because they generate code that is not multi-threaded safe? But that is strange that such a simple bug would be present in such a mature software.


      2. Does the build script that uses the makefile that uses configure have a bug, in that it uses make with -jn option? But that is also strange, because many makefiles use configure scripts and it would be unreasonable to require all of them to be slow and not use -jn.



      The failure above is real, I have seen it. I think I understand the mechanism of the failure. What I am confused about, is who has the bug?







      autotools






      share|improve this question















      share|improve this question













      share|improve this question




      share|improve this question








      edited Feb 1 at 21:34







      user322908

















      asked Feb 1 at 21:28









      user322908user322908

      419517




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