Norm Matloff's POSYBL Web Page

Contents:

• What Is POSYBL?

• Installation

• Environment and Path

• Differences between POSYBL and Standard Linda

• Compiling My POSYBL Front-End Program

• Compiling Your POSYBL Application Program

• Running Your POSYBL Application Program

• Bugs in POSYBL

• Debugging Your POSYBL Application Program

• Some Notes on Internals

What is POSYBL?

POSYBL is a nice implementation of the Linda parallel processing environment by G. Schoinas.

Installation:

If you wish to install POSYBL (with my modifications), first go to the src directory and copy my files NMsys_util.c and NMtmanager.c to sys_util.c and tmanager.c, respectively. Click here to get those two files.

Then from the src directory, type

make 

Afterward, copy the executables (startup, system and tmanager) to ../bin and libposybl.a to ../lib.

The package compiles and runs on SunOS 4.1 and MIPS-based DEC Ultrix machines. It does not compile on newer Solaris systems. Though it compiles under HP-UX there seems to be a fundamental runtime problem, at least on our CSIF machines. On our SGIs, the system will compile if one comments out "signal ( SIGQUIT, exit )" and changes calls to vfork() to fork(), but again there is a fundamental runtime problem.

Environment and path:

Differences between POSYBL and standard Linda:

POSYBL is a fairly straightforward Linda implementation, except for the following two points:

• The tuple components are assembled using function calls. For example, instead of simply putting the string "xyz" in a call to out(), we write

  lstring("xyz")
  

  Following is an example from MatMult.c our sample program available here.

  in(lstring("next row"),qlint(&Row));
  out(lstring("next row"),lint(Row+1));
  

  The first statement searches for and removes from the tuple space a 2-tuple whose first component is the string "next row" and the second component is some integer. The value of the second component is then place in Row. The second line outputs to the tuple space a 2-tuple whose first component is the string "next row", and whose second components is the values of Row+1.

• Instead of eval() initiating a process, it invokes an execution of the worker program on some remote machine, using rsh. (See the discussion on startup files below.)

Compiling my POSYBL front-end program:

To run your code, you will need a front-end program which calls eval() and your "worker" program which is invoked by eval(). I've written the front end for you, under the name POSYBLFrontEnd.c, available here. If it is not already in your $POSYBLDIR/bin directory, compile it, by typing

gcc -g -o POSYBLFrontEnd POSYBLFrontEnd.c $POSYBLDIR/lib/libposybl.a

and then make sure it is somewhere in your search path.

Compiling your POSYBL application program:

To compile your POSYBL application code, say worker.c, do:

gcc -g -o worker worker.c $POSYBLDIR/lib/libposybl.a

Running your POSYBL application program:

To run your POSYBL application code:

• Make sure that all machines on which you will be running your application are listed in your ~/.rhosts file.

• Prepare your startup file, which tells POSYBL the path of tmanager, the directory location of your "worker" program, and the machines you wish to run on. Here is a sample:

  chimi 1
  #0 ~matloff/Pub/POSYBL/bin/tmanager
  #2 ~matloff/Pub/POSYBL/examples
  garnacha 1
  #0 ~matloff/Pub/POSYBL/bin/tmanager
  #2 ~matloff/Pub/POSYBL/examples
  

  Here the machines chimi and garnacha are assigned the speeds 1, the location of tmanager is given on each machine and the directory containing the worker program is given. (Stick to the #0 and #2 designations shown here.)

• Then start the front end:

  POSYBLFrontEnd node_file worker_program number_of_workers cmd_line_args
  

  Note that the name of the worker program should NOT include a full path; it is simply the name within its directory.

  The command-line arguments, if any, are intended for use by your worker program. (Note: These are passed by the front end as integers, but as long as you are running on a homogeneous set of machines then these can be floats.)

When you leave the ACS machines, make sure to remember to kill the tuple manager processes! (Insert a check for this in your .logout file.)

tmanager port_number &

ps ax | grep tmanager