Develop Reference

Problem with do while loop that jumps out despite false condition

Newbie here! I've run into problems with some inconsistency when running the do while loop which surrounds the Try/Catch block.
Messing back and forth with different inputting makes the loop jump out despite its condition, which at multiple occasions should be true and run the block once again. Instead it ends up at "Number already exists" random number of times. It's obviously a hickup somewhere... Am I using it in the wrong way?
static void Main(string[] args)
{
int[] numbers = new int[10];
int input = 0;
int numRangeMin = 1;
int numRangeMax = 25;
bool duplicateNumber = false;
bool loop = true;
Console.WriteLine("\n Fill in a number:");
for (int i = 0; i < numbers.Length; i++)
{
do
{
do
{
try
{
Console.Write(" {0}: ", i + 1);
input = int.Parse(Console.ReadLine());
duplicateNumber = numbers.Contains(input); // Check if number already has been entered
loop = false;
}
catch (System.FormatException)
{ Console.WriteLine(" Only integers between {0}-{1} Try again!\n", numRangeMin, numRangeMax); }
catch (System.OverflowException)
{ Console.WriteLine(" Number is too big! Enter a number between {0}-{1}\n", numRangeMin, numRangeMax); }
} while (loop == true);
// Report if we attempt to insert a duplicate.
if (duplicateNumber)
{
Console.WriteLine("Number already exists");
}
else if (input > numRangeMax)
{
Console.WriteLine(" Too large:\n", numRangeMin, numRangeMax);
i--;
}
}
while (duplicateNumber == true); // Keep asking while we don't get a unique number.
numbers[i] = input; // Store the number
}
}

Your loop variable is defined outside the outer do loop, so it will retain it's value whenever you change it, that will lead to the inner loop not to be executed after the first time it has been set as false.
Define loop in side the outer loop or set it to true prior to the execution of the inner loop.
//...
do
{
loop = true;
do
{
try
{
//...
Also, the same will happen with the duplicateNumber variable because it's declared outside the for loop

Worker Threads Blocking When ConcurrentQueue has too many items

This is a weird one, I have a Thread[] of worker threads which each process items in a ConcurrentQueue<string> until the queue is empty, at which point the rest of the program continues.
This works until about ~1500 items at which point all threads stay blocked in the WaitSleepJoin state and never process any of the items in the queue.
I've tried stepping through my code and it appears that the threads are still created, still started and are alive but get blocked immediately and never run their relevant function.
I'm completely flummoxed so any help would be appreciated!
The relevant sections of code are below:
Main Thread Segment:
ConcurrentQueue<string> convertionQueue = new ConcurrentQueue<string>();
List<Thread> converterThreads = new List<Thread>();
Directory.GetFiles(_folderOne, "*.fdf", SearchOption.AllDirectories).ToList().ForEach(file => convertionQueue.Enqueue(file));
Directory.GetFiles(_folderTwo, "*.fdf", SearchOption.AllDirectories).ToList().ForEach(file => convertionQueue.Enqueue(file));
int filesDone = 0;
int totalFiles = convertionQueue.Count;
progressBar.Maximum = totalFiles;
panel1.Visible = true;
for (int i = 0; i < Environment.ProcessorCount; i++)
{
converterThreads.Add(new Thread(() => ConvThreadWorker(convertionQueue, ref filesDone)));
}
converterThreads.ForEach(thread => thread.Start());
DateTime lastTick = DateTime.Now;
int lastFilesDone = 0;
int[] valuesSpeed = { 1, 1, 1, 1, 1 };
int[] valuesTime = { 1, 1, 1, 1, 1 };
int counter = 0;
while (converterThreads.Any(thread => thread.IsAlive))
{
TimeSpan t = DateTime.Now - lastTick;
int deltaFiles = filesDone - lastFilesDone;
double speed = (float)t.TotalMilliseconds <= 0.0 ? 0.0 : deltaFiles / (float)t.TotalMilliseconds;
double tMinus = speed <= 0 ? 0.0 : (totalFiles - filesDone) / speed;
int currentSpeed = (int)(speed * 1000);
int currentTime = (int)(tMinus / 1000);
valuesSpeed[counter] = currentSpeed;
valuesTime[counter] = currentTime;
lblFilesLeft.Text = string.Format("{0}/{1}", filesDone, totalFiles);
lblSpeed.Text = valuesSpeed.Sum() / 5 + " /s";
lblTime.Text = valuesTime.Sum() / 5 + " s";
lblFilesLeft.Update();
lblSpeed.Update();
lblTime.Update();
progressBar.Value = filesDone;
progressBar.Update();
lastTick = DateTime.Now;
lastFilesDone = filesDone;
counter = ++counter % 5;
Thread.Sleep(500);
}
Worker Function:
private void ConvThreadWorker(ConcurrentQueue<string> queue, ref int fileCounter)
{
while (!queue.IsEmpty)
{
string file;
if (queue.TryDequeue(out file))
{
ConvToG(file);
fileCounter++;
}
}
}
Convertion Function:
private void ConvToG(string file)
{
MessageBox.Show("Entering Convertion Function");
if (!_fileCreationDictionary.ContainsKey(file))
{
DateTime lastTimeModified = File.GetLastWriteTime(file);
_fileCreationDictionary.AddOrUpdate(file, lastTimeModified, (key,oldvalue)=>lastTimeModified);
}
ProcessStartInfo procStart = new ProcessStartInfo
{
Arguments = file,
UseShellExecute = true,
FileName = Fdfg,
WindowStyle = ProcessWindowStyle.Hidden
};
Process process = new Process {StartInfo = procStart};
MessageBox.Show("Starting convertion process");
process.Start();
process.WaitForExit();
MessageBox.Show("Finished");
}
The confusing part appears to be how this all revolves around the number of items in the queue, yet there appears to be no overflow.
UPDATE: Adding the mbox's shows that it freezes on the process.Start() section of code, with no errors and will not proceed past that point.
UPDATE 2: If UseShellExecute = false the code works. Which is very confusing to say the least.

I have done something similar with threads spawning processes to collate data. I had issues around the actual process starting and hanging. What I did to get my program working was something like this:
using (Process process = Process.Start(startInfo)) {
if(process.WaitForExit(timeOutMilliseconds)) {
MessageBox.Show("Process exited ok");
//...snip
} else {
MessageBox.Show("Process did not exit in time!");
//...snip
process.Kill();
}
}
There is a bit more going on in the background, regarding limiting the number of running process, etc, but I found that occasionally, for an unknown reason, that I would see several process in the task manager just hanging around forever.
Hope that helps?

WinForm C# "new Process" in infinite loop causing application to crash

I have a requirement for which I need my block of code to run infinitely (The exit is an interrupt based on button click).
In each iteration, I am creating a Process, starting it, manipulating the output and then disposing the Process.
void status()
{
do{
Process test1 = new Process();
test1.StartInfo.FileName = "doSomething"; // doSomething is executable
test1.StartInfo.UseShellExecute = false;
test1.StartInfo.CreateNoWindow = true;
test1.StartInfo.RedirectStandardOutput = true;
test1.StartInfo.RedirectStandardError = true;
test1.Start();
string output = test1.StandardOutput.ReadToEnd();
test1.WaitForExit();
if (Regex.IsMatch(output, "DEVICE_READY", RegexOptions.IgnoreCase))
{
pictureBox2.BackColor = Color.Green;
}
else
{
pictureBox2.BackColor = Color.Yellow;
}
test1.Dispose();
}while(true);
}
The problem is the application is crashing with this code. If I just remove the loop, it works fine.
I checked while debugging, memory usage of the application keeps on increasing with each iteration of the loop, making the application crash at one point.
What I understood is Dispose() will release all the resources... so memory should not increase with each iteration.
Could someone please help to understand what is causing the memory usage increase?

What I do when I have to deal with hungry processes (eg. pictures manipulation) is to call the garbage collector explicitly.
This is not the cleanest way (costs a lot), but reasonnably used, it does the trick.
void status()
{
// will be used to explicitly call the garbage collector
const int COLLECT_EVERY_X_ITERATION = 10;
// store the current loop number
int currentIterationCount = 0;
do
{
// increase current iteration count
currentIterationCount++;
using (Process test1 = new Process())
{
test1.StartInfo.FileName = "doSomething"; // doSomething is executable
test1.StartInfo.UseShellExecute = false;
test1.StartInfo.CreateNoWindow = true;
test1.StartInfo.RedirectStandardOutput = true;
test1.StartInfo.RedirectStandardError = true;
test1.Start();
string output = test1.StandardOutput.ReadToEnd();
test1.WaitForExit();
if (Regex.IsMatch(output, "DEVICE_READY", RegexOptions.IgnoreCase))
{
pictureBox2.BackColor = Color.Green;
}
else
{
pictureBox2.BackColor = Color.Yellow;
}
}
// Explicitly call garbage collection every 10 iterations
if (currentIterationCount % COLLECT_EVERY_X_ITERATION == 0)
GC.Collect(GC.MaxGeneration, GCCollectionMode.Forced);
} while (true);
}

Process StandardOutput ReadToEnd get null/empty string when multiple processes

I try to use Parallel.For to run process and get output parallelly.
Sample code like this:
internal class Program
{
private static void Main(string[] args)
{
var bag = new ConcurrentBag<string>();
Parallel.For(0, int.MaxValue, i =>
{
bag.Add(MyMethod());
});
}
public static string MyMethod()
{
using (var a = new Process())
{
a.StartInfo.FileName = "A.exe";
a.StartInfo.RedirectStandardError = true;
a.StartInfo.RedirectStandardInput = true;
a.StartInfo.RedirectStandardOutput = true;
a.StartInfo.CreateNoWindow = true;
a.StartInfo.UseShellExecute = false;
a.StartInfo.ErrorDialog = false;
a.StartInfo.WindowStyle = ProcessWindowStyle.Hidden;
a.Start();
string output = a.StandardOutput.ReadToEnd();
a.WaitForExit();
return output; // sometime output will be null
}
}
}
A.exe code
internal class Program
{
private static void Main(string[] args)
{
for (int i = 0; i < 10; i++)
{
for (int j = 0; j < 40; j++)
{
Console.Write("A");
}
Console.Write(Environment.NewLine);
}
}
}
Does anyone know why output will null and how could I avoid get null result?

I have tried to figure out why get null in stream.
If I add Thread.Sleep() before A.exe output, main process's ReadToEnd() will wait for A.exe output and get result.
Only one situation will cause null stream is the A.exe exit and no output.
This will let ReadToEnd() get null and Peek() didn't help because A.exe is exit and no longer output anymore.
I think my problem is my program is running at a heavy loading Windows Server 2003 R2 32bit, Process.Start() didn't get exception when the process can't start. It cause no output to stream, the process exit and stream close.

How do count down in C# with Console.Clear(), and multi-thread

I'm a beginner in C#. I'm developing a console game and I have a problem with Thread in C#.
My game will display a top bar where count down timer runs. I try with a thread, I use Console.Clear() to clear old number then replace by new number on one line (59,58,57...). My game display a message to user input user's data on center screen or anywhere,...etc. But, when I start the thread countdown, it clear console screen, also, it clear message that user can input user's data. Can you help me and explain how to start 2 threads, do more various tasks?
using System; using System.Threading;
namespace ConsoleApplication1 {
class Program {
static void Main(string[] args) {
Program m = new Program();
Thread pCountDown = new Thread(new ThreadStart(
m.DisplayCountDown
));
Thread pDisplayForm = new Thread(new ThreadStart(
m.DisplayForm
));
pCountDown.Start();
pDisplayForm.Start();
Console.ReadKey();
}
private void DisplayCountDown() {
for (int i = 60; i >= 0; --i) {
Console.Write("Time: {0}",i);
Thread.Sleep(1000);
Console.Clear();
}
}
private void DisplayForm() {
while (true) {
Console.Write("Enter your number: ");
int a = Int32.Parse(Console.ReadLine());
Console.WriteLine(a);
Console.ReadLine();
}
}
}
}
Error:
My error
I want like this:
Image (Sorry, i'm a new member): Like this

You don't need thread nor to clear the console. Simply use Console.SetCursorPosition() and Console.Write() as suggested here, so you can overwrite the number.

You do not need to clear the console. Console.Write() writes over the existing characters, so just change the cursor position with Console.SetCursorPosition(x,y);
For example:
string mystring = "put what you want to right here";
Console.SetCursorPosition(0,0); //the position starts at 0 just make a note of it
Conolse.Write(mystring);
//now when you are ready to clear the text and print something over it again
//just add this
//now first erase the previous text
for(int i = 0; i< mystring.Length; i++)
{
Console.SetCursorPosition(i,0);
Console.Write(' ');
}
//now write your new text
mystring = "something else";
Console.SetCursorPosition(0,0);
Console.Write("mystring");

Here's a sample DisplayCountDown which doesn't clear the whole screen every second:
private void DisplayCountDown()
{
for (int i = 20; i >= 0; --i)
{
int l = Console.CursorLeft;
int t = Console.CursorTop;
Console.CursorLeft = 0;
Console.CursorTop = 0;
Console.Write("Time: {0} ", i);
Console.CursorLeft = l;
Console.CursorTop = t;
Thread.Sleep(1000);
}
}
However, this still leaves some issues. In my case I saw "Enter your number" appearing on the top line and being overwritten, so had to add the line
if (Console.CursorTop == 0) Console.CursorTop = 1;
inside the while loop. Also, if the user enters enough numbers, the countdown scrolls out of view, and if you try to scroll up to look at it, setting the cursor position automatically scrolls back.
I also had intermittent issues with int.Parse throwing an exception, presumably caused by the countdown changing at some critical point of the user's input.