public class Program
{
static void Main(string[] args)
{
var myThread = new TestThread();
Thread t = new Thread(new ThreadStart(myThread.PrintName));
Thread t1 = new Thread(new ThreadStart(myThread.PrintType));
t.Start();
t1.Start();
Console.Read();
}
}
public class TestThread
{
public void PrintName()
{
for (int i = 1; i <= 50; i++)
{
Console.WriteLine("Name {0}", i);
}
}
public void PrintType()
{
for (int i = 100; i <= 180; i++)
{
Console.WriteLine("Type {0}", i);
}
}
}
Here How can i fixed it show that i can generate output in sequential i.e
first output of Name then only output of Type... Also I want to know about using Lock() in threads? where can i get good example. I am beginners in threading and need v.simple example.
Try this:
var myThread = new TestThread();
var x=Task.Factory.StartNew(() => myThread.PrintName());
x.ContinueWith(p => PrintType());
x.Wait();
You can look at this
There are multiple other articles, just google for 'introduction threading c#'.
The purpose of threads is to allow things to happen at the same time. If you want things to happen one after another (i.e. sequentially), then do not use threads:
var obj = new TestThread();
obj.PrintName();
obj.PrintType();
Console.Read();
Or put PrintName and PrintType into the same thread, in order to keep the UI responsive:
var myThread = new TestThread();
Thread t = new Thread(new ThreadStart(
() => {
myThread.PrintName(); myThread.PrintType();
}
));
t.Start();
// Do things in the UI meanwhile
for (i = 0; i < 100; i++) {
Console.WriteLine("UI thread {0}", i);
}
Console.Read();
//This will run two operation in sequence.
public class TestThread
{
public object obj = new object();
public void PrintName()
{
Monitor.Enter(obj);
for (int i = 1; i <= 50; i++)
{
Console.WriteLine("Name {0}", i);
}
Monitor.Exit(obj);
}
public void PrintType()
{
Monitor.Enter(obj);
for (int i = 100; i <= 180; i++)
{
Console.WriteLine("Type {0}", i);
}
Monitor.Exit(obj);
}
}
That will do the trick, you should read carefully and try to do it with 3 loops by yourself:
private static void SimpleLockTest()
{
Task[] myTasks = new Task[2];
myTasks[0] = Task.Factory.StartNew(() =>
{
LockTestThreadOne();
});
myTasks[1] = Task.Factory.StartNew(() =>
{
LockTestThreadTwo();
});
Task.WaitAll(myTasks);
Console.WriteLine("Done, press ENTER to quit");
Console.ReadLine();
}
private static object locker = new object();
private static void LockTestThreadOne()
{
Monitor.Enter(locker);
for (int i = 1; i <= 50; i++)
{
Console.WriteLine("Name {0}", i);
Monitor.Pulse(locker);
Monitor.Wait(locker);
}
Monitor.Exit(locker);
}
private static void LockTestThreadTwo()
{
Monitor.Enter(locker);
for (int i = 100; i <= 180; i++)
{
Console.WriteLine("Type {0}", i);
Monitor.Pulse(locker);
Monitor.Wait(locker, 10);
}
Monitor.Exit(locker);
}
Related
I have an abstract class which runs threads:
protected volatile bool HasError = false;
public void Run()
{
var readingThread = new Thread(ReadInFile);
var compressingThreads = new List<Thread>();
for (var i = 0; i < Environment.ProcessorCount; i++)
{
var j = i;
ProcessEvents[j] = new AutoResetEvent(false);
compressingThreads.Add(new Thread(() => Process(j)));
}
var writingThread = new Thread(WriteOutFile);
readingThread.Start();
foreach (var compressThread in compressingThreads)
{
compressThread.Start();
}
writingThread.Start();
WaitHandle.WaitAll(ProcessEvents);
OutputDictionary.SetCompleted();
writingThread.Join();
Console.WriteLine(!HasError ? "Successfully competed" : "Error");
}
Well, and I don't know how I can check the Exception?
This is class realizes abstract class.
This is one method :
protected override void Process(int processEventId)
{
try
{
while (InputQueue.Dequeue(out Chunk chunk) && !HasError)
{
var compressedChunk = GZip.GZip.CompressByBlocks(chunk.Bytes);
OutputDictionary.Add(chunk.Id, compressedChunk);
}
ProcessEvents[processEventId].Set();
}
catch (Exception e)
{
HasError = true;
}
}
As you can see, I change the value of a variable when I catch an exception, but will it work? I do not understand how to check.
The better answer is probably not to use Threads but use Parallel.For(), it manages your errors and also has better options to handle workload.
But in your current setup, just add a wrapper method:
var j = i;
ProcessEvents[j] = new AutoResetEvent(false);
compressingThreads.Add(new Thread(() => SafeCallProcess(j) ));
and
private void SafeCallProcess(int j)
{
try
{
Process (j);
}
catch(Exception e)
{
// deal with it
}
}
You could move the Set() to the wrapper too, up to your taste I guess.
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Closed 6 years ago.
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I am totally new to multithreading. I am try to work on a simple test
I have a list of number from 1 to 100. The function I want to multithread is simply a function to multi the number by 5 then console.writeline the result
class Program
{
public static List data = new List();
public static void Main(string[] args)
{
new Program().run();
foreach(int d in data)
{
Console.WriteLine(d);
}
}
int multiply (int a){
return 5 * a;
}
void run()
{
int threadCount = 5;
Task[] workers = new Task[threadCount];
Task.Factory.StartNew(consumer);
for (int i = 0; i < threadCount; ++i)
{
int workerId = i;
Task task = new Task(() => worker(workerId));
workers[i] = task;
task.Start();
}
for (int i = 0; i < 100; ++i)
{
Console.WriteLine("Queueing work item {0}", i);
inputQueue.Add(i);
Thread.Sleep(50);
}
Console.WriteLine("Stopping adding.");
inputQueue.CompleteAdding();
Task.WaitAll(workers);
outputQueue.CompleteAdding();
Console.WriteLine("Done.");
Console.ReadLine();
}
void worker(int workerId)
{
Console.WriteLine("Worker {0} is starting.", workerId);
foreach (int workItem in inputQueue)
{
int b= multiply(workItem);
data.Add(b);
Console.WriteLine("Worker {0} is processing item {1}." ,workerId,b);
Thread.Sleep(100); // Simulate work.
outputQueue.Add(workItem); // Output completed item.
}
Console.WriteLine("Worker {0} is stopping.", workerId);
}
void consumer()
{
Console.WriteLine("Consumer is starting.");
foreach (var workItem in outputQueue.GetConsumingEnumerable())
{
Console.WriteLine("Consumer is using item {0}", workItem);
Thread.Sleep(25);
}
Console.WriteLine("Consumer is finished.");
}
BlockingCollection<int> inputQueue = new BlockingCollection<int>();
BlockingCollection<int> outputQueue = new BlockingCollection<int>();
}
Is this what you're asking?
using System;
using System.Collections.Generic;
using System.Threading;
class Program
{
static void Main(string[] args)
{
List<int> list = new List<int>();
for (int i = 0; i <= 100; i++) { list.Add(i); }
foreach (int value in list)
{
Thread thread = new Thread(() => PrintNumberTimesFive(value));
thread.Start();
}
Console.ReadLine();
}
static void PrintNumberTimesFive(int number)
{
Console.WriteLine(number * 5);
}
}
I have a probably simple question about the task factory. I have to following code:
In this task is a loop that is polling data from the RS232 and a counter that stops polling after 10 times. After this "doCollect" will be set to false.
And now comes the strange thing: The task runs repeatedly. The caller code is:
// class Main()
RS232DataAquisition _RS232DataAquisition = new RS232DataAquisition();
public override void Run()
{
System.Diagnostics.Stopwatch timeout = new System.Diagnostics.Stopwatch();
timeout.Start();
_RS232DataAquisition.Start();
while ((timeout.ElapsedMilliseconds <= (dataGatherTime_inSeconds * 1000)) && _RS232DataAquisition.DoCollect)
{
System.Threading.Thread.Sleep(100);
}
timeout.Stop();
_RS232DataAquisition.Stop();
}
Per my understanding the Run() function should start the thread and return into the while-loop waiting for the thread to finish. But it never does?!
Here's the code for ReadDataFromRS232:
// sealed class RS232DataAquisition
private bool doCollect = false;
public bool DoCollect
{
get { return doCollect; }
}
public void Start()
{
doCollect = true;
currentTask = System.Threading.Tasks.Task.Factory.StartNew(() =>
{
this.ReadDataFromRS232();
});
}
private void ReadDataFromRS232(int NumtoRead = 10)
{
var port = new System.IO.Ports.SerialPort(PortName);
int waitCount = 5;
var portExists = System.IO.Ports.SerialPort.GetPortNames().Any(x => x == PortName);
if (!portExists)
{
throw new ArgumentException("Port does not exist!");
}
while (port.IsOpen && waitCount-- > 0)
{
doCollect = false;
Wait();
}
doCollect = true;
if (!port.IsOpen)
{
port.Open();
port.NewLine = _NewLine;
port.ReadTimeout = 2000;
int number;
try { }
finally { }
port.Write("flashon\r");
while (doCollect && (_readCounter <= NumtoRead))
{
string s;
try
{
s = port.ReadLine();
}
catch
{
s = "-1";
}
int i;
if (int.TryParse(s, out i))
{
number = Convert.ToInt32(s, 10);
}
else
{
number = 0;
}
lock (thisLock) _data.Add(number);
_readCounter++;
}
port.Write("flashoff\r");
port.Close();
port.Dispose();
Wait(); Wait();
}
}
private void Wait()
{
System.Threading.Thread.Sleep(10);
System.Threading.Thread.SpinWait(1);
}
I don't get, why "ReadDataFromRS232" is beeing repeated until the timeout stops this task.
Thank you for any help :)
EDIT: Added some missing code.
As Dennis said the problem seemed to come from the missing volatile. It works now even though I have no idea why it didn't before.
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When I execute this code in command line, it's working fine:
class Program
{
private static List<Ping> pingers = new List<Ping>();
private static List<string> value = new List<string>();
private static int instances = 0;
private static object #lock = new object();
private static int result = 0;
private static int timeOut = 2500;
private static int ttl = 7;
public static void Main()
{
string baseIP = "192.168.1.";
Console.WriteLine("Pinging destinations of D-class in {0}*", baseIP);
CreatePingers(254);
PingOptions po = new PingOptions(ttl, true);
System.Text.ASCIIEncoding enc = new System.Text.ASCIIEncoding();
byte[] data = enc.GetBytes("");
SpinWait wait = new SpinWait();
int cnt =1;
Stopwatch watch = Stopwatch.StartNew();
foreach (Ping p in pingers)
{
lock (#lock)
{
instances += 1;
}
p.SendAsync(string.Concat(baseIP, cnt.ToString()), timeOut, data, po);
cnt += 1;
}
//while (instances > 0)
//{
// wait.SpinOnce();
//}
watch.Stop();
for (int i = 0; i < value.Count; i++)
{
Console.WriteLine(value[i]);
}
DestroyPingers();
Console.WriteLine("Finished in {0}. Found {1} active IP-addresses.", watch.Elapsed.ToString(), result);
Console.ReadKey();
}
public static void Ping_completed(object s, PingCompletedEventArgs e)
{
lock (#lock)
{
instances -= 1;
}
if (e.Reply.Status == IPStatus.Success)
{
string sa = string.Concat("Active IP: ", e.Reply.Address.ToString());
value.Add(sa);
//Console.WriteLine(sa);
String diachiip = e.Reply.Address.ToString();
result += 1;
}
else
{
//Console.WriteLine(String.Concat("Non-active IP: ", e.Reply.Address.ToString()))
}
}
private static void CreatePingers(int cnt)
{
for (int i = 1; i <= cnt; i++)
{
Ping p = new Ping();
p.PingCompleted += Ping_completed;
pingers.Add(p);
}
}
private static void DestroyPingers()
{
foreach (Ping p in pingers)
{
p.PingCompleted -= Ping_completed;
p.Dispose();
}
pingers.Clear();
}
}
But when I convert from it to window form, it doesn't work. I don't kwow why, I have tried many different ways...
Code is here:
public partial class Form1 : Form
{
public static List<Ping> pingers = new List<Ping>();
public static List<string> value = new List<string>();
public static int instances = 0;
public static object #lock = new object();
public static int result = 0;
public int timeout = 2500;
public static int ttl = 7;
public Form1()
{
InitializeComponent();
}
public void btnscan_Click(object sender, EventArgs e)
{
string baseIP = "192.168.1.";
//int kt = Int32.Parse(txtkt.Text);
//int start = Int32.Parse(txtstart.Text);
CreatePingers(254);
PingOptions po = new PingOptions(ttl, true);
System.Text.ASCIIEncoding enc = new System.Text.ASCIIEncoding();
byte[] data = enc.GetBytes("");
int cnt = 1;
Stopwatch watch = Stopwatch.StartNew();
foreach (Ping p in pingers)
{
lock (#lock)
{
instances += 1;
}
p.SendAsync(string.Concat(baseIP, cnt.ToString()), timeout, data, po);
cnt += 1;
}
watch.Stop();
//Result alway return 0
lst1.Items.Add(result.ToString());
lst1.Items.Add(value.Count.ToString());
for (int i = 0; i < value.Count; i++)
{
lst1.Items.Add(value[i]);
lst1.Items.Add("\n");
}
DestroyPingers();
string a = "Finished in " + watch.Elapsed.ToString() + ". Found " + result + " active IP-addresses.";
lst1.Items.Add(a);
}
public static void CreatePingers(int kt)
{
for (int start = 1; start <= kt; start++)
{
// class System.Net.NetworkInformation.Ping
Ping p = new Ping();
p.PingCompleted += Ping_completed();
pingers.Add(p);
}
}
public static PingCompletedEventHandler Ping_completed()
{
PingCompletedEventHandler a = new PingCompletedEventHandler(abc);
return a;
}
static void abc(object s, PingCompletedEventArgs e)
{
value.Add("abc");
lock (#lock)
{
instances -= 1;
}
if (e.Reply.Status == IPStatus.Success)
{
string abcd = string.Concat("Active IP: ", e.Reply.Address.ToString());
value.Add(abcd);
result += 1;
}
}
public static void DestroyPingers()
{
foreach (Ping p in pingers)
{
p.PingCompleted -= Ping_completed();
p.Dispose();
}
pingers.Clear();
}
}
What is wrong in this code?
Method SendAsync returns 0 because you are not waiting for it to complete. You are missing await and async (see msdn):
async void btnscan_Click(object sender, EventArgs e)
{
...
await p.SendAsync(string.Concat(baseIP, cnt.ToString()), timeout, data,
...
}
SpinWait was making code to work in console application. In winforms you should not use SpinWait (nor Sleep) in UI thread. You can create another thread (e.g. by using Task) and then you can copy/paste code from console application 1-to-1. But then you will need to use Invoke each time when you want to access UI controls.
async/await is really better.. if it will work (I concluded that from method name, I've no idea what method does, nor how to use it).
Perhaps I miss one thing, if SendAsync returns value, then you can get it by (the requirement to mark method where you use await with async still):
var result = await p.SendAsync(...);
I have a function that reads numbers from console and writes them to queue and a massive of threads that should read numbers from queue, calculate factorials and write it to file.
static void Main(string[] args)
{
int threadsNumber = 0;
Console.WriteLine("Enter the number of threads: ");
while ((Int32.TryParse(Console.ReadLine(), out threadsNumber) == false)||(threadsNumber <= 0))
{
Console.WriteLine("You need to enter a positive number!");
}
Console.Clear();
Queue<int> numbersQueue = new Queue<int>();
Thread [] threadMas = new Thread[threadsNumber];
for (int i = 0; i < threadsNumber; i++)
{
threadMas[i] = new Thread(() => ThreadProc.ThreadProcStart(numbersQueue));
threadMas[i].Start();
}
//some code...
ThreadProc:
class ThreadProc
{
private static object locker = new object();
public static void ThreadProcStart(Queue<int> queue)
{
while (true)
{
int num = Deq(queue); //Checks if queue is empty. If not -
//Returns first element
if (num != -1)
{
BigInteger bigInt = Factorial.FactTree(num); //factorical
Writer.WriteToFile(num + " factorial: " + bigInt, "result.txt"); //write to file
}
else
{
// Here I need to add something
Thread.Sleep(0);
}
}
}
public static int Deq(Queue<int> queue)
{
lock (locker)
{
if (queue.Count != 0)
{
return queue.Dequeue();
}
return -1;
}
}
}
I need to stop all threads when all calculations are done. How can i mark thread as "unactive" when the queue is empty without actually aborting it?
Use BlockingCollection, which underneath the covers uses ConcurrentQueue. Your code will be soooo much simpler and you won't have to worry about subtle locking bugs.
Your code would then look something like this:
static void Main(string[] args)
{
int threadsNumber = 0;
Console.WriteLine("Enter the number of threads: ");
while ((Int32.TryParse(Console.ReadLine(), out threadsNumber) == false) || (threadsNumber <= 0))
{
Console.WriteLine("You need to enter a positive number!");
}
Console.Clear();
BlockingCollection<int> queue = new BlockingCollection<int>();
Thread[] threadMas = new Thread[threadsNumber];
for (int i = 0; i < threadsNumber; i++)
{
threadMas[i] = new Thread(ProcessQueue);
threadMas[i].Start(queue);
}
string userInput = null;
do
{
Console.WriteLine("Enter a number: ");
userInput = Console.ReadLine();
if (userInput != "stop") {
queue.Add(int.Parse(userInput)); // These numbers get process by the threads in parallel.
}
} while (userInput != "stop");
queue.CompleteAdding(); // Use this to signal that no more items will be added to the queue.
// Now the main thread exits.
// But the program stays alive until the other threads finish
// clearing the queue.
}
private static void ProcessQueue(object data)
{
BlockingCollection<int> queue = (BlockingCollection<int>)data;
foreach (var num in queue.GetConsumingEnumerable()) // This will automatically exit the loop once CompleteAdding is called and the queue is empty.
{
BigInteger bigInt = Factorial.FactTree(num); //factorical
Writer.WriteToFile(num + " factorial: " + bigInt, "result.txt"); //write to file
}
}