Final Review B

In systems where threads can be given different priorities, locking can undermine the priority system whenever a high-priority thread desires a lock held by a low-priority thread: Either the system must temporarily grant the low-priority thread a high priority so that it can finish its work with the lock, or else the high-priority thread will be stalled while the low-priority thread completes its work.

Both prevent conflicts between threads attempting simultaneously accessing the HashMap. However, the single-lock HashMap will lead to reduce performance, since it will permit only one thread at a time to access the HashMap, whereas a ConcurrentHashMap will allow simultaneously access when the requests don't conflict (such as when the requests map to different buckets of the hash table).

This is the go-on operator: Given “A; B”, the value of A is computed before B, and the overall value of the expression is the value of B.

For instance, the expression “print(3); 5” represents first computing the value of print(3) then the value of 5, and the overall result is 5.

The declaration of first sym creates a constant: first sym cannot later be changed. By contrast, second sym is a variable whose value can later be changed with a statement such as “second sym := 4”.

A pure function is one that basically has no side effects: It does not perform I/O, access any memory beyond its own local memory and what is accessible through its arguments, or call non-pure functions.

Without lazy, this program would print 2 three times.

A function operates on numeric vectors as parameters and produces a numeric vector as a result, whereas an operator operates on functions as parameters and produces a function as a result. Examples of function include ‘÷’ for division and ‘↓’ for dropping items from a vector; examples of operators include ‘/’ for folding/reducing a function (for example, ‘+/’ creates a function that will sum the values of an vector) or ‘¨’ to apply a function to each item of a vector.

+/÷1+ι100