When wxProcess::Kill() launches wxProcess::OnTerminate() ?
na...@centrum.cz
Hello,
I have ubuntu 20.04 OS with wxWidgets 3.0.5. I have a custom
Process class (inherits from wxProcess) with OnTerminate()
function overridden. When I kill a process associated with an
instant of MyProcess class with MyProcess::Kill(), according to
the documentation of the wxProcess::OnTerminate():
https://docs.wxwidgets.org/3.0/classwx_ ...
4cbb72a172
the OnTerminate() function should not be called. But in my case it
is. Regradless of the used terminate flag.
I want to know, if this should not happen at all - mistake is in
my code, or if this is an expected behavior. If it is, then under
which circumstances is the OnTerminate() launched, when the
process is "killed" with MyProcess::Kill().
Additinal info:
I launch the command asynchronously with wxExecute("a.out",
wxEXEC_ASYNC | wxEXEC_MAKE_GROUP_LEADER, myProcess);
The program a.out has this implementation
------------------------------------------------------------
#include <iostream>
int main(int argc, char *argv[]){
int k;
std::cout << "Narg = " << argc - 1 << std::endl;
for(k = 1; k < argc; ++k){
std::cout << argv[k] << std::endl;
}
std::cerr << "Fail";
while(true){
}
return 127;
}
------------------------------------------------The flag returned from MyProcess::Kill() function is always wxKILL_OK.
Thanks,
Dalibor
PB
PB
Hi PB,
thank you for your prompt reply a for writing a minimal example. I do not have cmd.exe at hand, nor its code to compile and use it. If you send it to me, I can try it out in my code.
1. I could compile your code with no problems, but when launched I received this error:
An assertion failed: /usr/include/wx-3.0-unofficial/wx/strvararg.h(462): assert "(argtype & (wxFormatStringSpecifier<T>::value)) == argtype" failed in wxArgNormalizer(): format specifier doesn't match argument type
I am familiared with all the commands in the example except Log messages. Therefore, I commented out all code with them a redirected the output to stdout and stderr with std::cout and std::cerr. The code worked then. See the changed code at the end of my message.
--------------------
QUOTATION: " Dalibor, I assume if you run the linked code
verbatim except replacing "cmd" with "a.out", MyProcess::OnKill()
is still called there? "
-------------------
Yes, wxKill() is still called. See the terminal output below.
------------
QUOTATION: "Since you posted the code of the child process instead of the one calling it: Does the child process actually matter or does the issue manifest with any process?"
------------
I apologize for not sending the code invoking the wxExecute (and
my laziness). I will do my best next time. I admire, and thanks
again, that you did this instead of me.
I have tried to launch inkscape with the same result:
wxExecute("inkscape", wxEXEC_ASYNC | wxEXEC_MAKE_GROUP_LEADER,
&m_process). Here is the terminal output, which is the same
for both a.out and inkscape, except pid and inkscape warning:
------------
TERMINAL OUTPUT FOR INKSCAPE:
Process started, pid = 4751
Going to kill the process in 3 seconds.
** (org.inkscape.Inkscape:4751): WARNING **: 18:42:52.002: Fonts
dir '/home/dalibor/.config/inkscape/fonts' does not exist and will
be ignored.
Attempting to kill the process...
Process killed.
OnTerminate(): pid = 4751, status = -15
inkscape
TERMINAL OUTPUT FOR A.OUT:
Process started, pid = 4838
Going to kill the process in 3 seconds.
Numer = 0
FailAttempting to kill the process...
Process killed.
OnTerminate(): pid = 4838, status = -15
a.out
------------
-------------------------------------
CODE:
#include <wx/wx.h>
#include <wx/process.h>
class MyProcess : public wxProcess
{
public:
wxString cmd;
void OnTerminate(int pid, int status) override
{
//wxLogMessage("OnTerminate(): pid = %d, status = %d",
pid, status);
std::cout << "OnTerminate(): pid = "<< pid
<< ", status = " << status << std::endl;
std::cout << cmd <<std::endl;
}
};
class MyFrame : public wxFrame
{
public:
MyFrame() : wxFrame(nullptr, wxID_ANY, "Test")
{
/*wxLog::SetActiveTarget(new wxLogTextCtrl(new
wxTextCtrl(this, wxID_ANY, wxEmptyString,
wxDefaultPosition, wxDefaultSize, wxTE_MULTILINE |
wxTE_READONLY |
wxTE_RICH2)));*/
m_process.cmd = wxString::FromUTF8("a.out");
if ( wxExecute(m_process.cmd, wxEXEC_ASYNC |
wxEXEC_MAKE_GROUP_LEADER, &m_process) )
{
//wxLogMessage("Process started, pid = %d.",
m_process.GetPid());
std::cout << "Process started, pid = " <<
m_process.GetPid() << std::endl;
m_timer.SetOwner(this);
m_timer.StartOnce(3000);
//wxLogMessage("Going to kill the process in 3
seconds.");
std::cout << "Going to kill the process in 3
seconds." << std::endl;
}
Bind(wxEVT_TIMER, [this](wxTimerEvent&)
{
//wxLogMessage("Attempting to kill the process...");
std::cout << "Attempting to kill the
process..." << std::endl;
if ( wxProcess::Kill(m_process.GetPid()) ==
wxKILL_OK )
//wxLogMessage("Process killed.");
std::cout << "Process killed." <<
std::endl;
else
//wxLogError("Could not kill the process.");
std::cerr << "Could not kill the process."
<< std::endl;
} );
}
private:
MyProcess m_process;
wxTimer m_timer;
};
class MyApp : public wxApp
{
bool OnInit() override
{
(new MyFrame)->Show();
return true;
}
}; wxIMPLEMENT_APP(MyApp);
--------------------------------------------------------------
Thanks,
Dalibor
na...@centrum.cz
Hi PB,
I appologize for the private reply.
Thanks for your effort. You approved my doublts about the
wxProcess::Kill() function. I will wait if anyone else contrubutes
to elucidation of the problem.
Thanks,
Dalibor
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Carsten Arnholm
> Thanks for your effort. You approved my doublts about the
> wxProcess::Kill() function. I will wait if anyone else contrubutes to
> elucidation of the problem.
wxProcess::Kill(m_process.GetPid(), SIGNAL_TERMINATE).
I have some working code that does that,but I can't remember why
SIGNAL_TERMINATE is used.
Carsten Arnholm
jon bird
Windows anyway. I ended up stepping through the code for Kill and a key
thing to note is that the the default behaviour (ie. without specifying
the signal) differs between GUI applications and console apps. In the
former, it attempts to close the app by sending a (I think) WM_QUIT
message, in the latter it does nothing. You have to pass in wxSIGKILL
in order to terminate a console process, which ultimately results in a
call to TerminateProcess (and in my case, a subsequent call to
OnTerminate). That sort of makes sense because in my experience, there
is no other way to kill a console process.
I would hope you'd get the same thing with a GUI app but maybe if it
thinks the WM_QUIT succeeded, it assumes the window has closed. Given
Explorer (not sure what msys64 is but sounds "system" related) is going
to be a fairly unique case, it may be worth checking the behaviour with
a more normal app - Notepad for example.
Other point I observed - which I included as a big comment in my code...
void OnTerminate(int pid, int status) override
{
/* This statement in the wiki:
If the wxEVT_END_PROCESS event sent after termination is processed
by the parent, then it is responsible for deleting the wxProcess
object which sent it. However, if it is not processed, the object
will delete itself and so the library users should only delete
those objects whose notifications have been processed (and call
wxProcess::Detach for others). This also means that unless you're
going to process the wxEVT_END_PROCESS event, you must allocate the
wxProcess class on the heap.
We aren't attaching an event handler here so the implication here
is that we need to create this class on the heap. Indeed, when it
was on the stack, the process crashes shortly after the dialog gets
closed. However what *doesn't* appear to happen is the object
deleting itself automatically ie. our destructor never gets called
UNLESS we call the OnTerminate method in the base class - below. */
wxProcess::OnTerminate(pid, status);
}
Hope this helps.
Rgs,
Jon.
On Wed, 27 Oct 2021 20:11:36 +0200
"na...@centrum.cz" <na...@centrum.cz> wrote:
> Hi PB,
>
> I appologize for the private reply.
>
>
> Thanks for your effort. You approved my doublts about the
> wxProcess::Kill() function. I will wait if anyone else contrubutes to
> elucidation of the problem.
>
>
> Thanks,
>
> Dalibor
>
>
> On 27. 10. 21 19:48, PB wrote:
> > Dalibor somehow replied to my personal e-mail instead to the group
> > (please do not do that), I am pasting that at the end of the email.
> >
> > Firstly, I used wxLogMessage() because GUI programs on Windows do
> > not show console. "cmd" is a console command processor built into
> > Windows. The assert was probably because I used %d printf formatter
> > for wxProcess::GetPid() but it returns long and not int and unlike
> > on Windows, these two are different in 64-bit on Linux.
> >
> > Now the important stuff: I have noticed that when calling
> > wxProcess::Kill(m_process.GetPid()), its window disappeared but
> > https://groups.google.com/d/msgid/wx-users/f358b0d4-72f1-4d16-b9e6-7f832a08a5f5n%40googlegroups.com
>
--
--
== jon bird - software engineer
== <reply to address _may_ be invalid, real mail below>
== <reduce rsi, stop using the shift key>
== posted as: news 'at' onasticksoftware 'dot' co 'dot' uk
Gunter Königsmann
PB
Attempting to kill 'cmd' with wxSIGTERM.
Error: Could not kill the process, wxKill() returned wxKILL_ERROR.
Attempting to kill 'cmd' with wxSIGKILL.
Process killed successfully.
MyProcess::OnTerminate(): pid = 15448, status = -1
Attempting to kill 'notepad' with wxSIGTERM.
Process killed successfully.
MyProcess::OnTerminate(): pid = 2984, status = 0
Attempting to kill 'notepad' with wxSIGKILL.
Process killed successfully.
MyProcess::OnTerminate(): pid = 9200, status = -1
na...@centrum.cz
Hello PB,
Thank you for testing this out. I agree with the conclusion: When the process is killed successfully (return value of wxProcess::Kill() is wxKILL_OK), the OnTerminate() function is launched. Due to my experience, the conclusion can be generalized to include cmd apps as well. At least on Ubuntu.
Regards,PB--
Please read https://www.wxwidgets.org/support/mlhowto.htm before posting.
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Thanks,
Dalibor
PB
Vadim Zeitlin
P> I have just created a ticket for this, let's see what the devs are going to
P> say: https://trac.wxwidgets.org/ticket/19309
Thanks, I didn't have time to read through the entire thread here,
unfortunately, but I'll try to at least look a this ticket, although even
this might not happen immediately -- but I'll get to it, sooner or later.
Regards,
VZ
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