Chapter 7: Multithreading and Asynchronous Processing

Question 1

Name some threads that all .net applications have.

Answer 1

Garbage Collector Thread

Finalizer thread

Main thread

UI Thread

Question 2

TPL stands for

Answer 2

Task Parallel Library

Question 3

A .net application ends when all of the following kind of threads stop executing.

Answer 3

nonbackground.

Question 4

What is the difference between many core and multi-core?

Answer 4

Multi-Cor has more than one core that are all the same type.

Many core can have more than one of different type.s

Question 5

Disadvantages of multithreaded applications

Answer 5

1) Resource intensive (1 MB of memory per thread, overhead of scheduler swtiching between threads)
2) creation and destroying threads takes time.

Question 6

Method that causes current thread to wait on another

Answer 6

Join()

Question 7

Differences between manually created threads and thread pool threads

Answer 7

all threads from the ThreadPool are background threads

you can’t abort or interrupt a ThreadPool thread.

you can’t join a thread from the ThreadPool

Threads are reused from the threadppol

can’t control priority of threads from the ThreadPool

Question 8

technologies built on top of ThreadPool

Answer 8

Task Parallel Library (TPL)

Asynchronous Pattern Model (APM)

Event-based Asynchronous Pattern (EPA)

Task-based Asynchronous Pattern Model (TAP)

new async/await keywords

Question 9

Events of the Background worker class

Answer 9

DoWork (e.Result to hold the result)

RunWorkerCompleted

Question 10

TPL: ways to create a task (there are 4)

Answer 10

1) create an instance and call start()
2) static TaskFactory.StartNew
3) static Task.Run
4) Task continuation methods: Task.WhenAll, Task.WhenAny, TaskFactory.ContinueWhenAll, TaskFactory.ContinueWhenAny

Question 11

Hyperthreading

Answer 11

means that every core has two intruction pipelines, but only one execution engine.

Question 12

What was the only reason to use the TaskScheduler (given by the book)?

Answer 12

To force a task to be done by the current UI thread. TaskScheduler.FromCurrentSynchronizationContext().

Question 13

the three static methods of the Parallel class

Answer 13

For

ForEach

Invoke

Question 14

Three Continuation methods from Task and Task.Factory

Answer 14

Task.ContinueWith

Task.Factory.ContinueWhenAll

Task.Factory.ContinueWhenAny

Question 15

the compiler generates a warning if your method marked async is missing what?

Answer 15

an await statement

Question 16

Synchronization events (there are two)

Answer 16

EventWaitHandle (Set state as signalled)

CounDownEvent ()

Question 17

Barriers? No Idea, the example sucked and I need to stufy this more.

Answer 17

nuff said.

Question 18

Instead of using simple lock (object) this is a more primative version.

Answer 18

Monitor.Enter(object)

Monitor.Exit(object)

Question 19

The only lock free alternative described by the book

Answer 19

interlocked

Question 20

this should be avoided at all costs (locking)

Answer 20

lock.this()

Question 21

concurrent collections

Answer 21

BlockingCollection<t></t>

ConcurrentBag<t></t>

ConcurrentDictionary<tkey></tkey>

ConcurrentQueue<t></t>

ConcurrentStack<t></t>

Question 22

Cancellation

(Two major players)

Answer 22

CacellationTokenSource (class)

CancellationToken (struct)