[vbox-dev] savestate still hangs sometimes (reported before)

[Huihong Luo]

digged some more.
 
The freeze is caused by the following wait function (in red):
 
vmm\ssm.cpp
 
/**
* The I/O thread.
*
* @returns VINF_SUCCESS (ignored).
* @param hSelf The thread handle.
* @param pvStrm The stream handle.
*/
static DECLCALLBACK(int) ssmR3StrmIoThread(RTTHREAD hSelf, void *pvStrm)
{
PSSMSTRM pStrm = (PSSMSTRM)pvStrm;
ASMAtomicWriteHandle(&pStrm->hIoThread, hSelf); /* paranoia */
Log(("ssmR3StrmIoThread: starts working\n"));
if (pStrm->fWrite)
{
/*
* Write until error or terminated.
*/
for (;;)
{
int rc = ssmR3StrmWriteBuffers(pStrm);
if ( RT_FAILURE(rc)
|| rc == VINF_EOF)
{
Log(("ssmR3StrmIoThread: quitting writing with rc=%Rrc.\n", rc));
break;
}
if (RT_FAILURE(pStrm->rc))
{
Log(("ssmR3StrmIoThread: quitting writing with stream rc=%Rrc\n", pStrm->rc));
break;
}
if (ASMAtomicReadBool(&pStrm->fTerminating))
{
if (!ASMAtomicReadPtrT(&pStrm->pHead, PSSMSTRMBUF))
{
Log(("ssmR3StrmIoThread: quitting writing because of pending termination.\n"));
break;
}
Log(("ssmR3StrmIoThread: postponing termination because of pending buffers.\n"));
}
else if (!ASMAtomicReadPtrT(&pStrm->pHead, PSSMSTRMBUF))
{
rc = RTSemEventWait(pStrm->hEvtHead, RT_INDEFINITE_WAIT);  <=== stuck here
AssertLogRelRC(rc);
}
}
if (!ASMAtomicReadBool(&pStrm->fTerminating))
RTSemEventSignal(pStrm->hEvtFree);
}
else
{
/*
* Read until end of file, error or termination.
*/
for (;;)
{
if (ASMAtomicReadBool(&pStrm->fTerminating))
{
Log(("ssmR3StrmIoThread: quitting reading because of pending termination.\n"));
break;
}
int rc = ssmR3StrmReadMore(pStrm);
if ( RT_FAILURE(rc)
|| rc == VINF_EOF)
{
Log(("ssmR3StrmIoThread: quitting reading with rc=%Rrc\n", rc));
break;
}
if (RT_FAILURE(pStrm->rc))
{
Log(("ssmR3StrmIoThread: quitting reading with stream rc=%Rrc\n", pStrm->rc));
break;
}
}
if (!ASMAtomicReadBool(&pStrm->fTerminating))
RTSemEventSignal(pStrm->hEvtHead);
}
return VINF_SUCCESS;
}


--- On Mon, 8/9/10, Huihong Luo <huisinro at yahoo.com> wrote:


From: Huihong Luo <huisinro at yahoo.com>
Subject: Re: [vbox-dev] savestate still hangs sometimes (reported before)
To: "Huihong Luo" <huisinro at yahoo.com>
Cc: "vbox-dev at virtualbox.org" <vbox-dev at virtualbox.org>
Date: Monday, August 9, 2010, 7:40 PM



This change causes serious side effects, 
pls ignore it. Switching display mode won't work well. 

Sent from my iPhone

On Aug 9, 2010, at 1:53 PM, Huihong Luo <huisinro at yahoo.com> wrote:









did more debugging, and I found adding QCoreApplication::processEvents() might help to solve the freeze problems when powering off with saving state. Add "QCoreApplication::processEvents();" as first line to the following two methods.
 
if there is no other side effects, pls check in the changes:
 
UIMachineLogic.cpp:
 
void UIMachineLogic::sltMachineStateChanged()
{
// this is extremely import, freezes when hibernating otherwise
QCoreApplication::processEvents();
 
...
 
}
 
UIMachineView.cpp:
void UIMachineView::sltMachineStateChanged()
{
// this is extremely import, freezes when hibernating otherwise
QCoreApplication::processEvents();
...
}

--- On Mon, 8/9/10, Huihong Luo <huisinro at yahoo.com> wrote:


From: Huihong Luo <huisinro at yahoo.com>
Subject: Re: [vbox-dev] savestate still hangs sometimes (reported before)
To: vbox-dev at virtualbox.org
Date: Monday, August 9, 2010, 10:12 AM







I did some more investigation, the hang is caused by this call:
 
DECLCALLBACK(int) Console::saveStateThread(RTTHREAD Thread, void *pvUser)
{
 
int vrc = VMR3Save(that->mpVM,
task->mSavedStateFile.c_str(),
false, /*fContinueAfterwards*/
Console::stateProgressCallback,
static_cast<VMProgressTask*>(task.get()),
&fSuspenededBySave);                      <====
 
}
 
after 0% was printed out, VMR3Save() never returns.
 
Interestingly, the freeze might to do with 2D accleration, because if I disble 2D acceleration, it does not occur that often. 
 
The freeze won't occur if doing saving state from the vm GUI console, the Close button.
 
 


--- On Fri, 7/23/10, Huihong Luo <huisinro at yahoo.com> wrote:


From: Huihong Luo <huisinro at yahoo.com>
Subject: savestate still hangs sometimes (reported before)
To: vbox-dev at virtualbox.org
Date: Friday, July 23, 2010, 6:53 PM







when 2D acceleration is enabled
 
c:\virtualbox-dev\vbox\out\win.x86\release\bin>VBoxManage.exe controlvm vm1 savestate
0%...
 
hangs after 0% is displayed.
 
If doing from the Close menu, after dialog box is displayed, then choose Save State, then works well.
 
I tried to break the code, it seems stop inside some Windows message loop.
 
renderspu_init.c
renderSPUWindowThreadProc()
{
...
else
{
TranslateMessage(&msg);
DispatchMessage(&msg);
}
...
}
 
This is very annoying. need to fix these crash bugs when vm is shutting down.
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