100% CPU core use on W8.1 when viewer is minimized

[LRN]

Affects i686 and x86_64 servers.

Problem:
winvnc.exe consumes 100% of one CPU core.

• Install UltraVNC 1.2.0.5 on a Windows 8.1 machine (i686 or x86_64)
• Install w8hook.
• Connect to the server with UltraVNC viewer 1.2.x.x (only tested with x86_64 viewer).
• Observe minimal CPU usage by the server.
• Minimize the viewer window.
• Observe 100% CPU usage by the server.

Only affects a server that uses w8hook. Removing w8hook prevents this issue from happening, but increases load on the server (both winvnc.exe and dwm.exe) when viewer window is *not* minimized.
VNC settings don't seem to have any effect (the ones in "Properties").

Tightvnc viewer does not cause this behaviour. ssvnc viewer does not cause this behaviour either.

Log file on the server shows nothing unusual on the server side.

[LRN]

Anything else you need? I can produce stack traces, if you give me debug symbols (well, ProcessHacker's stack traces for VS debug symbols; gdb stack traces for MinGW debug symbols). Or maybe create a special version of winvnc.exe with profiling information, so that i can profile it and see where it spends most of its time. Or maybe there's a special loglevel to enable to see what's going on.

[Rudi De Vos]

issue found and corrected in source

[LRN]

When should i expect the next release that would have this fix in it?

[Rudi De Vos]

http://www.uvnc.eu/download/1206/winvnc_test.zip

min OS vista
32/64 exe winvnc.exe
changes
-fix 2xl initial screen send
-fix 100% cpu minimized w8hook on win8>=
-fix 5s timeout with multiple viewer connections

replace winvnc.exe to test

[LRN]

Tested it. I can confirm that the bug is fixed in this build.

[Philip N]

Tested here also on 3 machines running W2012R2 - this update has fixed the 100% CPU issue.