NPTL检查!

NPTL是Redhat在RHEL 3版本引入的线程特征!旨在取代LinuxThreads库!
这段是CentOS介绍的如何检查应用程序使用的是NPTL还是LinuxThreads,相信也适用于其他的NPTL实现系统!

• CentOS 3 introduced the Native POSIX Thread Library (NPTL) —
  an implementation of POSIX threading support that greatly improved
  performance, scalability, semantic correctness, and standards
  compliance over the LinuxThreads implementation used previously.
  
  While most threaded applications were not impacted by the
  introduction of NPTL, applications that relied on those semantics of
  LinuxThreads that were contrary to the POSIX specification would not
  operate correctly. As noted at the time of NPTL's introduction, CentOS
  recommended that such applications be updated so that they complied
  with POSIX (and could therefore use NPTL.)
  
  While support for LinuxThreads still exists for CentOS 4,
  this statement serves as advance notice that CentOS 5 will no longer
  include support for LinuxThreads. Therefore, applications that
  require LinuxThreads support must be updated before they will be able
  to work properly on a CentOS 5 system.
  
  
  

  Note

  
  Several workarounds exist that permit applications requiring the
  use of LinuxThreads to continue operation under CentOS 3 and 4.
  These workarounds include:
  

  
  

  
  
  • Using the LD_ASSUME_KERNEL environment
    variable to select LinuxThreads instead of NPTL at
    runtime
  
  
  • Using an explicit rpath to /lib/i686/
    
    or /lib/ to select LinuxThreads instead of
    NPTL at runtime
  
  
  • Statically linking the application to use LinuxThreads
    instead of NPTL (strongly
    discouraged)
  
  

  
  

  
  In order to determine whether an application is using NPTL or
  LinuxThreads, add following two environment variables to the
  application's environment:
  
  LD_DEBUG=libs
  
  LD_DEBUG_OUTPUT=<filename>
  
  (Where
  <filename>
  is the name to be given to each debug output log file. More than
  one file can be generated if the program forks other processes; all
  debug output log filenames include the PID of process generating the
  file.)
  
  Then start the application and use it as you normally
  would.
  
  If no debug output log file was produced, the application is
  statically linked. The application will not be affected by the
  missing LinuxThreads DSO but, as with all statically linked
  applications, no guarantees for compatibility are given if the
  application dynamically loads any code (directly via
  dlopen() or indirectly via NSS.)
  
  If one or more debug output log files were produced, review each
  one for any references to libpthread — in
  particular, a line also containing the string
  "calling init". The
  grep utility can do this easily:
  
  grep "calling init.*libpthread"
  <filename>.*
  
  (Where
  <filename>
  
  refers to the name used in the LD_DEBUG_OUTPUT
  environment variable.)
  
  If the path preceding libpthread is
  /lib/tls/, the application is using NPTL, and
  no further action needs to be taken. Any other path means that
  LinuxThreads is being used, and the application must be updated and
  rebuilt to support NPTL.