hdf5/test/AtomicWriterReader.txt

Atomic Tests Instructions
=========================

Purpose:
--------
This documents how to build and run the Atomic Writer and Reader tests.
The atomic test is to verify if atomic read-write operation on a system works.
The two programs are atomic_writer.c and atomic_reader.c.
atomic_writer.c: is the "write" part of the test; and
atomic_reader.c: is the "read" part of the test.

Building the Tests
------------------
The two test parts are automatically built during configure and make process.
But to build them individually, you can do in test/ directory:
$ gcc atomic_writer
$ gcc atomic_reader

Running the Tests
-----------------
$ atomic_writer -n <number of integers to write> -i <number of iterations for writer>
$ atomic_reader -n <number of integers to read> -i <number of iterations for reader>

Note**
(1) "atomic_data" is the data file used by both the writer/reader in the
    current directory.
(2) The value for -n should be the same for both the writer and the reader.
(3) The values for options n and i should be positive integers.
(4) For this version, the user has to provide both options -n and -i to run
    the writer and the reader.
(5) If the user wants to run the writer for a long time, just provides a
    large number for -i.

Examples
--------
$ ./atomic_writer -n 10000 -i 5
  Try to atomic write 10000 integers patterns 10000 time, and iterate the whole
  write process 5 times.

$ ./atomic_reader -n 10000 -i 2
  Try to atomic read 10000 integers patterns 10000 times, and iterate only once.
  A summary is posted at the end. If all atomic reads are correct, it will not
  show any read beyond "0 re-tries", that is all reads have succeeded in the
  first read attempt.

Remark:
You usually want the writer to iterate more times than the reader so that
the writing will not finish before reading is done.