1. Synchronization within monitors uses condition variables and two special operation wait and signal. A more general form of synchronization will be to have a single primitive, waituntil, which had an arbitrary boolean predicate as the parameter. Therefore, one can say, such as waituntil x < 0 or y+z < n. The signal primitive will no longer be required. This scheme is clearly more general, but it is not used. Why not? Hint, think about the implementation.

2. Assume there are 2 threads T1, T2. Please describe if the following solution provides the correct synchronization for critical section which satisfies three conditions:  mutual exclusion, bounded wait and make progress.
T1                                                                          T2
Shared: int t1Inside = 0, t2Inside = 0;                       while (1) {
while (1) {                                                             while (t1Inside);
  while (t2Inside);                                                     t2Inside = 2;
  t1Inside = 1;                                                         // critical section
   // critical section                                                         t2Inside = 0;
   t1Inside = 0;                                                           }
} 

3. Please prepare the pseudo code for the following problems:

1. Consider a pizza store which has 10 seats. A customer comes to buy pizza. If there is any unsold pizza left in the kitchen, he could get it immediately. If not, (s)he  needs to wait for chef to make one. After the customer gets the pizza, (s)he will grab a seat and start eating. If there is no seat, (s)he needs to wait. When (s)he finishes eating, (s)h would left the store. The chef in the kitchen just keeps making pizza. Though, (s)he stops if there are 5 unsold pizza left in the kitchen. If a customer come to buy one, (s)he resumes the work to make new pizza. Please prepare pseudo code for both customer and chef using semaphore to solve this problem, and synchronize chef and customers.

Programming Problem: 

4. prepare a multi-threaded program to solve producer and consumer problem.

• There are two types of worker thread: producer and consumer. A producer thread  randomly generate an integer between 0-100 (You could use random()/srandom()  or drand48()/srand48() to generate random number in C), and put it into the buffer. A consumer thread simple take the first integer from the buffer. A circular array must be used for the buffer. You don’t need loop for both types of thread. Each thread would exit after only consuming or producing one item (only once).

• Suppose total number of worker thread is 20, and buffer size is 10. Your program must randomly generate the number of producers and consumers. Their relationship must be : num_producers + num_consumers = num_threads, num_producer - num_consumer <= buffer_size, num_consumer <= num_producer, so that no thread will be blocked forever.  The order between consumer and producer threads must be arbitrary. Such as, you will not generate all producers(consumers) and then all consumers (producers). 

• Synchronize the producer and consumer.

• You could select any type of language (e.g. C/C++/Java) to execute this program. Your output will look like the following: 
Number of producer: 12 Number of consumer: 8
Thread 0 produce 63 in buffer 0, current number of items is 1
Thread 1 consume item 63 in buffer 0, current number of items is 0
Thread 3 produce 45 in buffer 1, current number of items is 1
Thread 5 produce 88 in buffer 2, current number of items is 2
Thread 4 consume item 45 in buffer 1, current number of items is 0
…....
…..
…...
There are still 4 items left in the buffer: 96,26,52,81

• Please check blackboard for more reference about pthread library if you select to use it.

• Please submit all source code and a simple readme file on how to compile your code and the sample output. Please zip all files into a single zip file and submit through blackboard.