Thread-safetyness of exceptions Topic is solved

[namo]

Is it safe to use exceptions within threads?

[megabyte]

What do you mean "safe" or "does not safe"? Which exceptions behavior do you expect?

You can use it in you threads, but exception thrown in a thread will not affect on other ones.

[namo]

Code: Select all

void CThread::Entry(void)
{
  try
  {
    printf("%i running in %p\n", wxThread::GetCurrentId(), this);
    wxThread::Sleep(3000);
    printf("%p %i throwing %s\n", this, wxThread::GetCurrentId(), "foo");
    throw "foo";
  }
  catch(const char* psz)
  {
    printf("%p %i catching %s\n", this, wxThread::GetCurrentId(), psz);
  }
}

I have two instances of wxThread-derived classes loaded and I when start both of them roughly at the same time I got this output:

Code: Select all

3256 running in 025249B8
3816 running in 02524AB0
025249B8 3256 throwing foo
02524AB0 3256 catching foo

So when two threads are in the same function and one throws an exception I catch it in the same thread but with the wrong instance of the class.

But then the threads execute in different functions everything works like it should.

[Game_Ender]

Threads by definition have different stacks and if I remeber my exception handling right (at least on linux and GCC) exceptions roll back the stack as they attempt to be caught. So this should happen independently in each thread.

Can you post a more complete example.

[megabyte]

I entered your thread code to a function of the console sample. It looks like

Code: Select all

wxThread::ExitCode MyDetachedThread::Entry()
{
	try
	{
		printf("%i running in %p\n", wxThread::GetCurrentId(), this);
		wxThread::Sleep(3000);
		printf("%p %i throwing %s\n", this, wxThread::GetCurrentId(), "foo");
		throw "foo";
	}
	catch(const char* psz)
	{
		printf("%p %i catching %s\n", this, wxThread::GetCurrentId(), psz);
	}     {
        wxCriticalSectionLocker lock(gs_critsect);
        if ( gs_counter == (size_t)-1 )
            gs_counter = 1;
        else
            gs_counter++;
    }

    for ( size_t n = 0; n < m_n; n++ )
    {
        if ( TestDestroy() )
        {
            m_cancelled = true;

            break;
        }

        wxPutchar(m_ch);
        fflush(stdout);

        wxThread::Sleep(100);
    }

    return 0;
}

The output is

*** Testing detached threads ***
336 running in 009569D8
2548 running in 00958140
880 running in 00956980
009569D8 336 throwing foo
00958140 2548 throwing foo
00956980 880 throwing foo
009569D8 336 catching foo
00958140 2548 catching foo
00956980 880 catching foo
BCABCABCABCABCABCABCABCABCABCA

Can you do the same modification on your pc? Do you have similar output? If yes, then please post the threads declaration and creation code.

BTW, the original wxThread::Entry methods returns wxThread::ExitCode (decared as void *).

[namo]

I found why it failed... A DLL I linked with was not build with -mthreads...

But still thanks for your help.