From: Janne Blomqvist Date: Sun, 6 Feb 2011 16:08:03 +0000 (+0200) Subject: Document libgfortran thread-safety X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=6985b4a110323bea66ca938532a63a4f936a422f;p=gcc.git Document libgfortran thread-safety From-SVN: r169864 --- diff --git a/gcc/fortran/ChangeLog b/gcc/fortran/ChangeLog index 7fc66e0e60f..55b1cf94b8d 100644 --- a/gcc/fortran/ChangeLog +++ b/gcc/fortran/ChangeLog @@ -1,3 +1,11 @@ +2011-02-06 Janne Blomqvist + + * gfortran.texi (Thread-safety): New section. + * intrinsic.texi (EXECUTE_COMMAND_LINE): Mention thread-safety. + (GETENV): Likewise. + (GET_ENVIRONMENT_VARIABLE): Likewise. + (SYSTEM): Likewise. + 2011-02-06 Paul Thomas PR fortran/47592 diff --git a/gcc/fortran/gfortran.texi b/gcc/fortran/gfortran.texi index a34d82e529d..54f245755a7 100644 --- a/gcc/fortran/gfortran.texi +++ b/gcc/fortran/gfortran.texi @@ -1157,6 +1157,36 @@ representation of @code{LOGICAL} variables in GNU Fortran is identical to C99 _Bool, except for a possible difference in storage size depending on the kind. + +@node Thread-safety of the runtime library +@section Thread-safety of the runtime library +@cindex thread-safety, threads + +GNU Fortran can be used in programs with multiple threads, e.g. by +using OpenMP, by calling OS thread handling functions via the +@code{ISO_C_BINDING} facility, or by GNU Fortran compiled library code +being called from a multi-threaded program. + +The GNU Fortran runtime library, (@var{libgfortran}), supports being +called concurrently from multiple threads with the following +exceptions. + +During library initialization, the C @code{getenv()} function is used, +which need not be thread-safe. Similarly, the @code{getenv()} +function is used to implement the @code{GET_ENVIRONMENT_VARIABLE} and +@code{GETENV} intrinsics. It is the responsibility of the user to +ensure that the environment is not being updated concurrently when any +of these actions are taking place. + +The @code{EXECUTE_COMMAND_LINE} and @code{SYSTEM} intrinsics are +implemented with the @code{system()} function, which need not be +thread-safe. It is the responsibility of the user to ensure that +@code{system()} is not called concurrently. + +Finally, for platforms not supporting thread-safe @code{POSIX} +functions, further functionality might not be thread-safe. For +details, please consult the documentation for your operating system. + @c --------------------------------------------------------------------- @c Extensions @c --------------------------------------------------------------------- diff --git a/gcc/fortran/intrinsic.texi b/gcc/fortran/intrinsic.texi index f0287f6e65c..ea5528fe111 100644 --- a/gcc/fortran/intrinsic.texi +++ b/gcc/fortran/intrinsic.texi @@ -4162,6 +4162,9 @@ the command, as returned by @code{system}. @code{CMDSTAT} is set to zero if the command line was executed (whatever its exit status was). @code{CMDMSG} is assigned an error message if an error has occurred. +Note that the @code{system()} call need not be thread-safe. It is the +responsibility of the user to ensure that @code{system()} is not +called concurrently. @item @emph{Standard}: Fortran 2008 and later @@ -5452,11 +5455,15 @@ END PROGRAM @item @emph{Description}: Get the @var{VALUE} of the environmental variable @var{NAME}. -This intrinsic routine is provided for backwards compatibility with -GNU Fortran 77. In new code, programmers should consider the use of +This intrinsic routine is provided for backwards compatibility with +GNU Fortran 77. In new code, programmers should consider the use of the @ref{GET_ENVIRONMENT_VARIABLE} intrinsic defined by the Fortran 2003 standard. +Note that @code{GETENV} need not be thread-safe. It is the +responsibility of the user to ensure that the environment is not being +updated concurrently with a call to the @code{GETENV} intrinsic. + @item @emph{Standard}: GNU extension @@ -5501,6 +5508,11 @@ END PROGRAM @item @emph{Description}: Get the @var{VALUE} of the environmental variable @var{NAME}. +Note that @code{GET_ENVIRONMENT_VARIABLE} need not be thread-safe. It +is the responsibility of the user to ensure that the environment is +not being updated concurrently with a call to the +@code{GET_ENVIRONMENT_VARIABLE} intrinsic. + @item @emph{Standard}: Fortran 2003 and later @@ -11779,6 +11791,10 @@ and environment-dependent. This intrinsic is provided in both subroutine and function forms; however, only one form can be used in any given program unit. +Note that the @code{system()} call need not be thread-safe. It is the +responsibility of the user to ensure that @code{system()} is not +called concurrently. + @item @emph{Standard}: GNU extension