Race Conditions & Locks

Question 1

Mutual Exclusion

Answer 1

limits access to a shared resource to one thread at a time; guarantees atomicity!!!

Question 2

Race Condition

Answer 2

condition where incorrect program output may be generated depending on the interleaving of instructions from multiple threads

Question 3

Critical section

Answer 3

the section of code that accesses shared resources

Question 4

Locks

Answer 4

thread synchronization mechanism that achieves mutual exclusion

Question 5

Atomic operation

Answer 5

program operations that run completely independently of any other processes

Question 6

Synchronization

Answer 6

a mechanism to ensure multiple loci do not simultaneously access the shared resources

Question 7

Shared Resource

Answer 7

anything of interest; represented in memory, so we can talk in terms of shared variables

Question 8

What is a deterministic ?

Answer 8

for the same input, the same output

Question 9

Correct output

Answer 9

any output from interleaving mutltiple threads is the same as an output from executing the threads sequentially; whatever output threads execute sequentially

Question 10

Atomicity of critical section

Answer 10

only one thread is in the critical section, and that thread must finish before another enters the critical section

Question 11

Benefits of synchronization

Answer 11

what you can do when outside of the bits where you are forced to be synchronised, and that other threads are free to go about their business if they aren’t accessing that variable

Question 12

Atomic Code

Answer 12

code that is executed by a thread invisibly from the point of view of other threads trying to execute the same code;