Models & Tools for Parallelism

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Foreword

The following exercises needs for you to access a Unix system. A Linux operating system would be better (because I didn't try these exercises on Solaris) but probably not mandatory.

1. Timeout

Using the alarms (SIGALRM) make a program that wait 10 seconds for a keyboard event, exit if none is given or wait for another 10 seconds if one key is pressed. Use the signal() function and then the sigaction() function.

2. Critical Code

Make a program the block all signals during the execution of the following piece of code:

int computation() {
  int i;
  float array[100];

  for (i=0; i < 100; i++)
    array[i] = 1000*sin(cos((float) i) + tan((float (100-i))));

  exit(0);
}            

Use the signal() function and then the sigaction() function (don't forget to restore the pending signals once the computation is finished).

3. Signal Pong

Make a program that fork and have the following behaviour:

• Once forked, the parent send a signal SIGUSR1 to its child and enter an infinite loop.
• The child wait in an infinite loop.
• Both (parent and child) when receiving a SIGUSR1 signal reply by the same (parent to child and child to parent).

What happen if you replace the infinites loops by pause(). Use the signal() function and then the sigaction() function.

4. Pipe Pong

Make a program that fork and have the following behaviour:

• Once forked, the parent send a message "pong" to its child and enter an infinite loop.
• The child wait in an infinite loop.
• Both (parent and child) when receiving a pong message reply by the same (parent to child and child to parent).

Use an unnamed pipe and then a named pipe.

5. Pipe Race

Try to create 1 master process and 10 racing processes where the master process is feeding a pipe with "Win", and then broadcast the signal SIGUSR1 to its group of process. When a racing process get the signal SIGUSR1, it tries to read the pipe, the one getting the "Win" message is out for the rest of the game. At the end of the game, each process has a number which is the round number in which it caught the message "Win".