Computer Science Homework Help

Question 1: Implement a multi-access threaded queue with multiple threads inserting and multiple threads extracting from the queue. Use mutex-locks to synchronize access to the queue. Document the time for 1000 insertions and 1000 extractions each by 64 insertion threads (producers) and 64 extraction threads (consumers).

Question 2: Repeat Problem 7.2 using condition variables (in addition to mutex locks). Document the time for the same test case as above. Comment on the difference in the times.

Question 3: Improve the binary tree search program by associating a lock with each node in the tree (as opposed to a single lock with the entire tree). A thread locks a node when it reads or writes it. Examine the performance properties of this implementation.

Question 4: Improve the binary tree search program further by using read-write locks. A thread read-locks a node before reading. It write-locks a node only when it needs to write into the tree node. Implement the program and document the range of program parameters where read-write locks actually yield performance improvements over regular locks.

Question 5: Implement a threaded hash table in which collisions are resolved by chaining. Implement the hash table so that there is a single lock associated with a block of k hashtable entries. Threads attempting to read/write an element in a block must first lock the corresponding block. Examine the performance of your implementation as a function of k.

Question 6: Write a threaded program for computing the Sieve of Eratosthenes. Think through the threading strategy carefully before implementing it. It is important to realize, for instance, that you cannot eliminate multiples of 6 from the sieve until you have eliminated multiples of 3 (at which point you would realize that you did not need to eliminate multiples of 6 in the first place). A pipelined (assembly line) strategy with the current smallest element forming the next station in the assembly line is one way to think about the problem.

Question 7: Consider a simple loop that calls a function dummy containing a programmable delay. All invocations of the function are independent of the others. Partition this loop across four threads using static, dynamic, and guided scheduling. Use different parameters for static and guided scheduling. Document the result of this experiment as the delay within the dummy function becomes large.