问题
I have a random rare AV in my application, which I cannot reproduce unfortunately.
exception message : Access violation at address 76FFD968 in module 'ntdll.dll'. Write of address 00000014.
main thread ($11a0):
76ffd968 +00099 ntdll.dll
76ffd872 +1b572 ntdll.dll RtlEnterCriticalSection
00470dca +0001e app.exe Graphics TCanvas.Lock
0047116b +0002f app.exe Graphics TCanvas.TryLock
00489cbd +00041 app.exe Controls FreeDeviceContexts
0048ea80 +0003c app.exe Controls TWinControl.MainWndProc
004a241c +00014 app.exe Forms StdWndProc
75a50d48 +00016 user32.dll CallWindowProcW
004ff768 +00048 app.exe TntControls 617 +12 TWinControlTrap.Win32Proc
004a241c +00014 app.exe Forms StdWndProc
76fd0107 +0002b ntdll.dll KiUserCallbackDispatcher
0048d463 +0005f app.exe Controls TWinControl.Destroy
00493049 +0001d app.exe Controls TCustomControl.Destroy
0040332c +00008 app.exe System TObject.Free
004ac369 +00035 app.exe Forms ValidateHintWindow
004ac5b8 +00230 app.exe Forms TApplication.ActivateHint
004ac161 +00029 app.exe Forms TApplication.HintTimerExpired
004a9fb6 +00022 app.exe Forms HintTimerProc
75a47bc5 +0000a user32.dll DispatchMessageA
004ab4fb +00083 app.exe Forms TApplication.ProcessMessage
004ab532 +0000a app.exe Forms TApplication.HandleMessage
004a8137 +00147 app.exe Forms TCustomForm.ShowModal
I'm using Tnt Unicode controls. from the error log I can tell that the cause of the problem is a Unicode hint window, and an invalid device context (?). I'm quit sure the Hint window Canvas is being Locked/Unlocked properly in the TCustomControl.WMPaint ancestor. But still I assume the DC is not valid, and can't figure out why - who is messing with the DC.
I am not looking you to debug my program. But maybe an idea on how to approach the issue. Has anyone had this issue with Tnt Unicode controls?
Any help would be much appreciated.
来源：https://stackoverflow.com/questions/40863225/access-violation-at-address-in-module-ntdll-dll-rtlentercriticalsection-with-t