Komposter

What best describes Lazy Synchronization?

• Using as few locks as possible

• Perform changes using flags and labels rather than full modifications

• Locking the entire method

• Only performing sequential work

What best describes Coarse-Grained Locking?

• Locking large parts of a method to prevent interleavings

• Dividing the code into a few lockable submethods

• Dividing the code into many lockable submethods

• Locking a block using one lock rather than multiple separate ones

What best describes Optimistic Synchronization?

• Replacing all locks with wait-free methods

• Replacing all wait-free methods with locks

• Performing changes first and only commit all after validation

• Validating and committing changes one-by-one

What best describes Fine-Grained Locking?

• Split objects into pieces with separate locks

• Using multiple locks for critical sections

• Using locks only when necessary, otherwise wait-free methods

• Using validations during locking to prevent bad interleavings

What best describes a "reduce" operation?

• Modifying each element of an array independent of eachother

• Modifying an array & Outputting a single value

• Modifying elements of an array depending on other elements

• Outputting a single value based on an array

Can hand-over-hand locking be implemented by Java's "synchronized" keyword?

• Yes

• No

• I don't know :(

Which of the following always generates "happens-before" relationships?

• Reading/Writing of volatile int

• Locking operations

• Program order inside a thread

• Reading/Writing of int

• Global program order

Which of the following can be used for parallel fork/join computations? (assuming left/right are the forked tasks)

• left.fork()

  left.join()

  right.compute()

• left.fork()

  right.fork()

  left.join()

  right.join()

• left.fork()

  left.join()

  right.fork()

  right.join()

• left.fork()

  right.compute()

  left.join()

• left.compute()

  right.compute()

Which of the following type returns a value in the context of a fork/join exercise?

• Recursive

• RecursiveTask

• RecursiveAction

• RecursiveValue

What is the/a "Sentinel"?

• A thread which performs additional tasks in lazy synch. (like deleting marked entries in the list)

• The root task of a fork/join tasktree

• Entires of an array without useful data but guaranteed to exist

• A different name for the "main" thread