Stopping a Thread
in [MFC]
|
From: brogers5884 on 16 Feb 2005 15:53 In my application I have some list controls that load fairly large amounts of data, a few thousand records, or the query to get the records just take a really large amount of time. So I created threads to load the list controls instead of locking up the front end while it tries to load and it works like a champ. My problem being is while the list is loading if the user closes that dialog by switching to another screen or trying to close the dialog the program errors out and shuts down. So I put code in the destructor of the list control that initiates that the thread: m_pThread->PostThreadMessage(WM_USER_STOPTHREAD,0,0); while(WaitForSingleObject(m_pThread->m_hThread, 1000) != WAIT_FAILED); Now I don't get immediate severe errors but the program hangs indefinitely on the WaitForSingleObject command. Any ideas on how I can get that thread to stop it's execution so the window can close gracefully and not lock up the program? Thank you.
From: JD on 16 Feb 2005 16:13 "brogers5884" <brogers5884(a)discussions.microsoft.com> wrote in message news:1051D7E5-C396-4231-B02E-3E0B1A9B3B09(a)microsoft.com... > In my application I have some list controls that load fairly large amounts of > data, a few thousand records, or the query to get the records just take a > really large amount of time. So I created threads to load the list controls > instead of locking up the front end while it tries to load and it works like > a champ. My problem being is while the list is loading if the user closes > that dialog by switching to another screen or trying to close the dialog the > program errors out and shuts down. So I put code in the destructor of the > list control that initiates that the thread: > > m_pThread->PostThreadMessage(WM_USER_STOPTHREAD,0,0); > while(WaitForSingleObject(m_pThread->m_hThread, 1000) != WAIT_FAILED); > > Now I don't get immediate severe errors but the program hangs indefinitely > on the WaitForSingleObject command. Any ideas on how I can get that thread > to stop it's execution so the window can close gracefully and not lock up the > program? Thank you. Is the thread running a message loop while it's loading the list controls???? If not, the thread will never see the message. Also, PostThreadMessage has some odd behavior -- a google on it might be helpful, I'm not remembering the details. A quick and dirty solution might be just to have a flag that's visible to the thread -- Set the flag and wait on the handle. On each iteration thru the lit control loading, check the flag and bail if appropriate. JD
From: AliR on 16 Feb 2005 16:35 I am assuming it is a UI thread and not a worker thread. Have you tried: m_pThread->PostQuitMessage(); AliR. "brogers5884" <brogers5884(a)discussions.microsoft.com> wrote in message news:1051D7E5-C396-4231-B02E-3E0B1A9B3B09(a)microsoft.com... > In my application I have some list controls that load fairly large amounts of > data, a few thousand records, or the query to get the records just take a > really large amount of time. So I created threads to load the list controls > instead of locking up the front end while it tries to load and it works like > a champ. My problem being is while the list is loading if the user closes > that dialog by switching to another screen or trying to close the dialog the > program errors out and shuts down. So I put code in the destructor of the > list control that initiates that the thread: > > m_pThread->PostThreadMessage(WM_USER_STOPTHREAD,0,0); > while(WaitForSingleObject(m_pThread->m_hThread, 1000) != WAIT_FAILED); > > Now I don't get immediate severe errors but the program hangs indefinitely > on the WaitForSingleObject command. Any ideas on how I can get that thread > to stop it's execution so the window can close gracefully and not lock up the > program? Thank you.
From: Joseph M. Newcomer on 16 Feb 2005 16:19 This works only if the thread returning to the message pump. And the WaitForSingleObject is almost certainly fatal. The fact that it times out is even more suspicious. In fact, the piece of code is remarkably silly, in that it simply loops; INFINITE would have been a more effective timeout. But why do you have to wait for it at all? And putting it in the destructor is probably the wrong place to put it. You should shut the thread down in the OnClose handler. The destructor is far too late. Read my essay on worker threads on my MVP Tips site. joe On Wed, 16 Feb 2005 12:53:01 -0800, "brogers5884" <brogers5884(a)discussions.microsoft.com> wrote: >In my application I have some list controls that load fairly large amounts of >data, a few thousand records, or the query to get the records just take a >really large amount of time. So I created threads to load the list controls >instead of locking up the front end while it tries to load and it works like >a champ. My problem being is while the list is loading if the user closes >that dialog by switching to another screen or trying to close the dialog the >program errors out and shuts down. So I put code in the destructor of the >list control that initiates that the thread: > >m_pThread->PostThreadMessage(WM_USER_STOPTHREAD,0,0); >while(WaitForSingleObject(m_pThread->m_hThread, 1000) != WAIT_FAILED); > >Now I don't get immediate severe errors but the program hangs indefinitely >on the WaitForSingleObject command. Any ideas on how I can get that thread >to stop it's execution so the window can close gracefully and not lock up the >program? Thank you. Joseph M. Newcomer [MVP] email: newcomer(a)flounder.com Web: http://www.flounder.com MVP Tips: http://www.flounder.com/mvp_tips.htm
From: brogers5884 on 16 Feb 2005 17:09
I don't want to wait for it at all, I want it to exit immediately. In the thread it just gets a recordset and then loops through the recordset and loads each record into a custom drawn list control. If you try to close that dialog while the thread is in it's loop loading the list control it blows up in glorious fashion each and every time. I'm just trying to find some way to tell that thread to stop doing anything and get out. Thanks for all of the responses. "Joseph M. Newcomer" wrote: > This works only if the thread returning to the message pump. And the WaitForSingleObject > is almost certainly fatal. The fact that it times out is even more suspicious. In fact, > the piece of code is remarkably silly, in that it simply loops; INFINITE would have been a > more effective timeout. > > But why do you have to wait for it at all? > > And putting it in the destructor is probably the wrong place to put it. > > You should shut the thread down in the OnClose handler. The destructor is far too late. > > Read my essay on worker threads on my MVP Tips site. > joe > > On Wed, 16 Feb 2005 12:53:01 -0800, "brogers5884" <brogers5884(a)discussions.microsoft.com> > wrote: > > >In my application I have some list controls that load fairly large amounts of > >data, a few thousand records, or the query to get the records just take a > >really large amount of time. So I created threads to load the list controls > >instead of locking up the front end while it tries to load and it works like > >a champ. My problem being is while the list is loading if the user closes > >that dialog by switching to another screen or trying to close the dialog the > >program errors out and shuts down. So I put code in the destructor of the > >list control that initiates that the thread: > > > >m_pThread->PostThreadMessage(WM_USER_STOPTHREAD,0,0); > >while(WaitForSingleObject(m_pThread->m_hThread, 1000) != WAIT_FAILED); > > > >Now I don't get immediate severe errors but the program hangs indefinitely > >on the WaitForSingleObject command. Any ideas on how I can get that thread > >to stop it's execution so the window can close gracefully and not lock up the > >program? Thank you. > > Joseph M. Newcomer [MVP] > email: newcomer(a)flounder.com > Web: http://www.flounder.com > MVP Tips: http://www.flounder.com/mvp_tips.htm > |