Debug Hacks

Total points: 40

• Watchpoint 7'
• Modifying variable 7'
• Conditional breakpoint 8'
• Switching threads 8'
• CyclicBarrier 10'

Doubly Linked List with Concurrency

• Requirement A (15')
  • Loop at least two times 5'
  • Lock each get-compute-set workflow 3'
  • No intervention[1] in CPU scheduling 4'
  • Correctly[2] starting a thread 1'
  • Wait for worker threads 2'
• Requirement B (30')
  • Wait for worker threads by using barriers 5'
  • No intervention in CPU scheduling 5'
  • Satisfy the worst[3] degree of concurrency 5'
  • The link structure is not corrupted [5] 5'
  • The size is equal to the actual size [5] 5'
  • No deadlock [4][5] 5'
• Requirement C (15')
  • Memoize the owner of each node 3'
  • Set the owner of head and tail 4'
  • Inside remove(), validate the node's owner 4'
  • Inside insert(), validate the node's owner 4'

NOTE:

• [1] Such as using Thread.sleep(), or any form of I/O INSIDE EACH LOOP to intervene the normal execution of the code.
• [2] Thread.start(), or submit() to a ThreadPool.
• [3] The worst concurrency we can accept is locking the whole table at each call of insert/remove
• [4] If a deadlock is discovered and you are using Thread.sleep() to wait for worker threads, only 5' are punished.
• [5] If you are attempting to implement a fine-grained(细粒度) synchronization but failed to resolve the deadlock problem, then only 3' are punished.

Punishment for such cases:

• Messy indent -4'
• Not recommended naming convention -2'