In my project I have a heavy part of code that should be executed on a separate thread without blocking UI. When debugger hits the breakpoint inside this code, VS2015 freezes for 5-10 seconds. After that, if I try to continue debug (by pressing Step Over, Step In or Continue), the app goes from paused state to working state, Debugging Tools are ticking, but nothing happens and there's 0% of CPU utilization. If I press Break All then, the "cursor" (don't know the correct term) is shown at Application.Run( new Form1() ); in Program.cs where Main() is.
As I'm pretty new to C#, I thought that there was some problem with my approach to multithreading, but apparently it happens whatever I try - using async/await with Tasks, using BackgroundWorker component, or simple new Thread(myFunc).Start().
Just to be clear.
- The code itself works perfectly fine.
- Debugger itself also works, no freezes and "deadlocks" on breakpoints in my main thread. If I launch the code from main thread - everything is fine.
- I also checked it in a fully new solution on a simple
for ( int i = 0; i < Int32.MaxValue; ++i )function - same problem. - Also checked on different versions of .NET: 4.6, 4.5, 4.0. Same everywhere.
- The problem doesn't appear neither in VS2010 (which I used before), nor in VS2013 (which I tried just to be sure that it's a VS2015 problem). However, my friend working with the same VS2015 also doesn't have this problem.
Edit: per request, code of test form where I keep getting the problem. Only three buttons, label, and BackgroundWorker. The overall scheme is similar to the code of the main project.
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
const int period = 10000;
void FuncAsync(IProgress<int> progress)
{
for ( int i = 0; i < Int32.MaxValue; ++i )
{
double part = (double)i / Int32.MaxValue;
int percent = (int)(part * 100.0);
if ( (i % period) == 0 )
progress.Report( percent );
}
}
void FuncBW(BackgroundWorker worker)
{
for ( int i = 0; i < Int32.MaxValue; ++i )
{
double part = (double)i / Int32.MaxValue;
int percent = (int)(part * 100.0);
if ( (i % period) == 0 )
worker.ReportProgress( percent );
}
}
void FuncThread()
{
for ( int i = 0; i < Int32.MaxValue; ++i )
{
double part = (double)i / Int32.MaxValue;
int percent = (int)(part * 100.0);
if ( (i % period) == 0 )
label1.Text = percent.ToString();
//yes, this one will cause exception of accessing UI from different thread
//if i press "Break" in the exception window, i will also get a 10sec freeze
}
}
private async void button1_Click(object sender, EventArgs e)
{
var progress = new Progress<int>(i => label1.Text = i.ToString() );
await Task.Factory.StartNew( () => FuncAsync( progress ),
TaskCreationOptions.LongRunning );
}
private void button2_Click(object sender, EventArgs e)
{
backgroundWorker1.RunWorkerAsync();
}
private void button3_Click(object sender, EventArgs e)
{
Thread t = new Thread(FuncThread);
t.Start();
}
private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)
{
FuncBW( (BackgroundWorker)sender );
}
private void backgroundWorker1_ProgressChanged(object sender, ProgressChangedEventArgs e)
{
label1.Text = e.ProgressPercentage.ToString();
}
}
I've experienced similar issues with VS2015 freezing (indefinitely) whilst debugging a multi thread WinForms application.
I had no problems debugging the same code in VS2013.
The problem appears to go away when I disable the VS hosting process (Project -> Properties -> Debug -> Enable the Visual Studio hosting process).
Hope that works for others.
After i checked "use managed compatibility mode" in options-debugging-general, thread debugging seems to work.
I had breakpoints in 2 different threads and Visual Studio was bouncing from one to the other as I stepped through. Eventually it froze with (Not Responding) in the title bar.
If I limited the breakpoints to just one thread, I would not experience the problem.
I had a similar issue. The other answers to this question did not resolve the issue for me, but they pointed me to the right direction. Apparently I had the Release configuration selected, instead of Debug.
After annoying hours, the answer of @Haggisatonal was it for me. Thank you very much!
The problem appears to go away when I disable the VS hosting process (Project -> Properties -> Debug -> Enable the Visual Studio hosting process).
but
"Tools -> Options -> Debugging -> General -> Enable property evaluation and other implicit function calls"
like in a nother Ticket, was not the resolution for me, maybe it helps temporairly others
I had the problem of visual studio 2008 freeze even after disabling the hosting process. What seems to be working for me is disabling address level debugging.
(VS2008) Tools (menu) -> Options -> Debugging -> General -> (uncheck) Enable address-level Debugging.
I suggest that you use a combilation of a Timer and WaitHandle in your code instead of the for loop that causes high CPU usage. I made a simple change to your code to ease the CPU usage. Hope that help.
public partial class Form1 : Form
{
EventWaitHandle _waitHandle ;
System.Timers.Timer _timer;
public Form1()
{
InitializeComponent();
_waitHandle = new EventWaitHandle(false, EventResetMode.AutoReset);
_timer = new System.Timers.Timer();
_timer.Interval = 100;
_timer.Elapsed += OnTimerElapsed;
_timer.AutoReset = true;
}
private void OnTimerElapsed(object sender, System.Timers.ElapsedEventArgs e)
{
_waitHandle.Set();
}
void FuncAsync(IProgress<int> progress)
{
_timer.Start();
int percent = 0;
while (percent <= 100)
{
if (_waitHandle.WaitOne())
{
progress.Report(percent);
percent++;
}
}
_timer.Stop();
}
void FuncBW(BackgroundWorker worker)
{
_timer.Start();
int percent = 0;
while (percent <= 100)
{
if (_waitHandle.WaitOne())
{
worker.ReportProgress(percent);
percent++;
}
}
_timer.Stop();
}
void FuncThread()
{
_timer.Start();
int percent = 0;
while (percent <= 100)
{
if (_waitHandle.WaitOne())
{
if (this.InvokeRequired)
{
this.Invoke((Action)delegate { label1.Text = percent.ToString(); });
}
else
{
label1.Text = percent.ToString();
}
percent++;
}
}
_timer.Stop();
}
... your other code
}
来源：https://stackoverflow.com/questions/32051488/visual-studio-2015-debug-doesnt-work-in-multithread-application