README

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===========================================================================

When submitting questions and problems, be sure to include as much
extra information as possible.  This web page details all the
information that we request in order to provide assistance:

     http://pmix.github.io/pmix/community/help/

The best way to report bugs, send comments, or ask questions is to
sign up on the PMIx mailing list, which is hosted by GoogleGroups:

        pmix@googlegroups.com

Because of spam, only subscribers are allowed to post to this list
(ensure that you subscribe with and post from exactly the same e-mail
address -- joe@example.com is considered different than
joe@mycomputer.example.com!).  You can subscribe to the list here:

     https://groups.google.com/d/forum/pmix

Thanks for your time.

===========================================================================

More information is available in the PMIx FAQ:

    http://pmix.github.io/pmix/faq/

We are in early days, so please be patient - info will grow as questions
are addressed.

===========================================================================

The following abbreviated list of release notes applies to this code
base as of this writing (12 November 2015):

General notes
-------------

- The majority of PMIx's documentation is here in this file, the
  included man pages, and on the web site FAQ
  (http://pmix.github.io/pmix/faq).  This will eventually be
  supplemented with cohesive installation and user documentation files.

- Systems that have been tested are:
  - Linux (various flavors/distros), 32 bit, with gcc
  - Linux (various flavors/distros), 64 bit (x86), with gcc, Intel,
    and Portland (*)
  - OS X (10.7 and above), 32 and 64 bit (x86_64), with gcc (*)

(*) Compiler Notes
--------------

- The Portland Group compilers prior to version 7.0 require the
  "-Msignextend" compiler flag to extend the sign bit when converting
  from a shorter to longer integer.  This is is different than other
  compilers (such as GNU).  When compiling PMIx with the Portland
  compiler suite, the following flags should be passed to PMIx's
  configure script:

  shell$ ./configure CFLAGS=-Msignextend ...

  This will compile PMIx with the proper compile flags

- Running on nodes with different endian and/or different datatype
  sizes within a single parallel job is supported in this release.
  However, PMIx does not resize data when datatypes differ in size
  (for example, sending a 4 byte double and receiving an 8 byte
  double will fail).


===========================================================================

Building PMIx
-----------------

PMIx uses a traditional configure script paired with "make" to
build.  Typical installs can be of the pattern:

---------------------------------------------------------------------------
shell$ ./configure [...options...]
shell$ make all install
---------------------------------------------------------------------------

There are many available configure options (see "./configure --help"
for a full list); a summary of the more commonly used ones follows:

INSTALLATION OPTIONS

--prefix=<directory>
  Install PMIx into the base directory named <directory>.  Hence,
  PMIx will place its executables in <directory>/bin, its header
  files in <directory>/include, its libraries in <directory>/lib, etc.

--disable-shared
  By default, libpmix is built as a shared library.  This switch disables
  this default; it is really only useful when used with
  --enable-static.  Specifically, this option does *not* imply
  --enable-static; enabling static libraries and disabling shared
  libraries are two independent options.

--enable-static
  Build libpmix as a static library.  Note that this option does *not* imply
  --disable-shared; enabling static libraries and disabling shared
  libraries are two independent options.

 --disable-show-load-errors-by-default
   Set the default value of the mca_base_component_show_load_errors MCA
   variable: the --enable form of this option sets the MCA variable to
   true, the --disable form sets the MCA variable to false.  The MCA
   mca_base_component_show_load_errors variable can still be overridden
   at run time via the usual MCA-variable-setting mechanisms; this
   configure option simply sets the default value.

   The --disable form of this option is intended for PMIx packagers
   who tend to enable support for many different types of networks and
   systems in their packages.  For example, consider a packager who
   includes support for both the FOO and BAR networks in their PMIx
   package, both of which require support libraries (libFOO.so and
   libBAR.so).  If an end user only has BAR hardware, they likely only
   have libBAR.so available on their systems -- not libFOO.so.
   Disabling load errors by default will prevent the user from seeing
   potentially confusing warnings about the FOO components failing to
   load because libFOO.so is not available on their systems.

   Conversely, system administrators tend to build a PMIx that is
   targeted at their specific environment, and contains few (if any)
   components that are not needed.  In such cases, they might want
   their users to be warned that the FOO network components failed to
   load (e.g., if libFOO.so was mistakenly unavailable), and thus
   some PMIx calls might unexpectedly return "not supported".

--with-platform=FILE
  Load configure options for the build from FILE.  Options on the
  command line that are not in FILE are also used.  Options on the
  command line and in FILE are replaced by what is in FILE.

Once PMIx has been built and installed, it is safe to run "make
clean" and/or remove the entire build tree.

VPATH and parallel builds are fully supported.

Generally speaking, the only thing that users need to do to use PMIx
is ensure that <prefix>/lib is in their LD_LIBRARY_PATH.  Users may
need to ensure to set LD_LIBRARY_PATH in their shell setup files (e.g.,
.bashrc, .cshrc) so that non-interactive rsh/ssh-based logins will
be able to find the PMIx library.

===========================================================================

PMIx Version Numbers and Binary Compatibility
-------------------------------------------------

PMIx has two sets of version numbers that are likely of interest
to end users / system administrator:

    * Software version number
    * Shared library version numbers

Both are described below, followed by a discussion of application
binary interface (ABI) compatibility implications.

Software Version Number
-----------------------

PMIx's version numbers are the union of several different values:
major, minor, release, and an optional quantifier.

  * Major: The major number is the first integer in the version string
    (e.g., v1.2.3). Changes in the major number typically indicate a
    significant change in the code base and/or end-user
    functionality. The major number is always included in the version
    number.

  * Minor: The minor number is the second integer in the version
    string (e.g., v1.2.3). Changes in the minor number typically
    indicate a incremental change in the code base and/or end-user
    functionality. The minor number is always included in the version
    number:

  * Release: The release number is the third integer in the version
    string (e.g., v1.2.3). Changes in the release number typically
    indicate a bug fix in the code base and/or end-user
    functionality.

  * Quantifier: PMIx version numbers sometimes have an arbitrary
    string affixed to the end of the version number. Common strings
    include:

    o aX: Indicates an alpha release. X is an integer indicating
      the number of the alpha release (e.g., v1.2.3a5 indicates the
      5th alpha release of version 1.2.3).
    o bX: Indicates a beta release. X is an integer indicating
      the number of the beta release (e.g., v1.2.3b3 indicates the 3rd
      beta release of version 1.2.3).
    o rcX: Indicates a release candidate. X is an integer
      indicating the number of the release candidate (e.g., v1.2.3rc4
      indicates the 4th release candidate of version 1.2.3).

Although the major, minor, and release values (and optional
quantifiers) are reported in PMIx nightly snapshot tarballs, the
filenames of these snapshot tarballs follow a slightly different
convention.

Specifically, the snapshot tarball filename contains three distinct
values:

   * Most recent Git tag name on the branch from which the tarball was
     created.

   * An integer indicating how many Git commits have occurred since
     that Git tag.

   * The Git hash of the tip of the branch.

For example, a snapshot tarball filename of
"pmix-v1.0.2-57-gb9f1fd9.tar.bz2" indicates that this tarball was
created from the v1.0 branch, 57 Git commits after the "v1.0.2" tag,
specifically at Git hash gb9f1fd9.

PMIx's Git master branch contains a single "dev" tag.  For example,
"pmix-dev-8-gf21c349.tar.bz2" represents a snapshot tarball created
from the master branch, 8 Git commits after the "dev" tag,
specifically at Git hash gf21c349.

The exact value of the "number of Git commits past a tag" integer is
fairly meaningless; its sole purpose is to provide an easy,
human-recognizable ordering for snapshot tarballs.

Shared Library Version Number
-----------------------------

PMIx uses the GNU Libtool shared library versioning scheme.

NOTE: Only official releases of PMIx adhere to this versioning
      scheme. "Beta" releases, release candidates, and nightly
      tarballs, developer snapshots, and Git snapshot tarballs likely
      will all have arbitrary/meaningless shared library version
      numbers.

The GNU Libtool official documentation details how the versioning
scheme works.  The quick version is that the shared library versions
are a triple of integers: (current,revision,age), or "c:r:a".  This
triple is not related to the PMIx software version number.  There
are six simple rules for updating the values (taken almost verbatim
from the Libtool docs):

 1. Start with version information of "0:0:0" for each shared library.

 2. Update the version information only immediately before a public
    release of your software. More frequent updates are unnecessary,
    and only guarantee that the current interface number gets larger
    faster.

 3. If the library source code has changed at all since the last
    update, then increment revision ("c:r:a" becomes "c:r+1:a").

 4. If any interfaces have been added, removed, or changed since the
    last update, increment current, and set revision to 0.

 5. If any interfaces have been added since the last public release,
    then increment age.

 6. If any interfaces have been removed since the last public release,
    then set age to 0.

Application Binary Interface (ABI) Compatibility
------------------------------------------------

PMIx provides forward ABI compatibility in all versions of a given
feature release series and its corresponding
super stable series.  For example, on a single platform, an pmix
application linked against PMIx v1.3.2 shared libraries can be
updated to point to the shared libraries in any successive v1.3.x or
v1.4 release and still work properly (e.g., via the LD_LIBRARY_PATH
environment variable or other operating system mechanism).

PMIx reserves the right to break ABI compatibility at new feature
release series.  For example, the same pmix application from above
(linked against PMIx v1.3.2 shared libraries) will *not* work with
PMIx v1.5 shared libraries.

===========================================================================

Common Questions
----------------

Many common questions about building and using PMIx are answered
on the FAQ:

    http://pmix.github.io/pmix/faq/

===========================================================================

Got more questions?
-------------------

Found a bug?  Got a question?  Want to make a suggestion?  Want to
contribute to PMIx?  Please let us know!

When submitting questions and problems, be sure to include as much
extra information as possible.  This web page details all the
information that we request in order to provide assistance:

     http://pmix.github.io/pmix/community/help/

Questions and comments should generally be sent to the PMIx mailing
list (pmix@googlegroups.com).  Because of spam, only
subscribers are allowed to post to this list (ensure that you
subscribe with and post from *exactly* the same e-mail address --
joe@example.com is considered different than
joe@mycomputer.example.com!).  Visit this page to subscribe to the
user's list:

     https://groups.google.com/d/forum/pmix

Make today an PMIx day!