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       MPI_Init_thread -  Initialize the MPI execution environment


       #include <mpi.h>
       MPI_Init_thread(int *pargc, char ***pargv, int requested, int *pprovided)


       pargc  - Pointer to the number of arguments
       pargv  - Pointer to the argument vector
              - Desired level of thread support
              - Given level of thread support


       LAM  currently supports MPI_THREAD_SINGLE , MPI_THREAD_SERIALIZED , and
       MPI_THREAD_FUNNELED .  MPI_THREAD_MULTIPLE is not yet  supported.   The
       use  of  MPI_INIT_THREAD  is  recommended instead of MPI_INIT if an MPI
       program   is   going    to    be    multi-threaded.     However,    the
       LAM_MPI_THREAD_LEVEL  environment  variable  can  be  used  to the same
       effect.  See MPI_Init(3) for more details.

       There  is  currently  no  distinction  between  MPI_THREAD_SINGLE   and
       MPI_THREAD_FUNNELED   .    An   application  using  MPI_THREAD_FUNNELED
       promises to never call MPI from a different thread than  the  one  that
       invoked MPI_INIT (or MPI_INIT_THREAD ).  LAM does no checking to ensure
       that this is true.  As such, no locks are placed around  MPI  calls  to
       ensure  that  only  one thread is making MPI calls at a time (since the
       application has promised that  only  one  thread  will  be  making  MPI

       Using  MPI_THREAD_SERIALIZED  will  cause LAM to place locks around all
       MPI calls such that only one thread will  be  able  to  enter  the  MPI
       library  at  a time; beware of this fact for portability with other MPI
       implementations.   Even  with  multiple  threads,  deadlock  is   still
       possible when using MPI_THREAD_SERIALIZED -- applications still need to
       be aware of this and code appropriately.

       Other than this  restriction,  this  function  behaves  identically  to
       MPI_INIT (see MPI_Init(3)).

       Note  that both MPI_INIT and MPI_INIT_THREAD are allowed to changed the
       requested thread level based  on  lower-level  device  and  SSI  module
       initializations.  For example, if a user application invokes MPI_Init ,
       some SSI modules may require threads and therefore upgrade  the  thread
       support level to something higher than MPI_THREAD_SINGLE .


       If an error occurs in an MPI function, the current MPI error handler is
       called to handle it.  By default, this error  handler  aborts  the  MPI
       job.   The  error  handler may be changed with MPI_Errhandler_set ; the
       predefined error handler MPI_ERRORS_RETURN may be used to  cause  error
       values  to  be  returned  (in C and Fortran; this error handler is less
       useful in with the C++ MPI  bindings.   The  predefined  error  handler
       MPI::ERRORS_THROW_EXCEPTIONS  should  be used in C++ if the error value
       needs to be recovered).  Note that MPI does not guarantee that  an  MPI
       program can continue past an error.

       All  MPI  routines  (except  MPI_Wtime  and MPI_Wtick ) return an error
       value; C routines as the value of the function and Fortran routines  in
       the  last  argument.   The  C++  bindings  for  MPI do not return error
       values; instead, error values are communicated by  throwing  exceptions
       of  type  MPI::Exception  (but  not  by  default).  Exceptions are only
       thrown if the error value is not MPI::SUCCESS .

       Note that if the MPI::ERRORS_RETURN handler is set in  C++,  while  MPI
       functions  will  return  upon an error, there will be no way to recover
       what the actual error value was.
              - No error; MPI routine completed successfully.
              - Invalid  argument.   Some  argument  is  invalid  and  is  not
              identified  by a specific error class.  This is typically a NULL
              pointer or other such error.
              - This error  class  is  associated  with  an  error  code  that
              indicates  that  an  attempt  was made to call MPI_INIT a second
              time.  MPI_INIT may only be called once in a program.
              - Other error; use  MPI_Error_string  to  get  more  information
              about this error code.


       MPI_Init, MPI_Finalize, lamboot, mpirun, lamhalt, lamssi


       For more information, please see the official MPI Forum web site, which
       contains the text  of  both  the  MPI-1  and  MPI-2  standards.   These
       documents contain detailed information about each MPI function (most of
       which is not duplicated in these man pages).


       The LAM Team would like the thank the MPICH Team for the handy  program
       to        generate        man        pages        ("doctext"       from    ),    the     initial
       formatting, and some initial text for most of the MPI-1 man pages.