Hi Tristan Thanks for the report. The new vnc maintainers will look into this.
Best regards, // Ola On Fri, Sep 02, 2011 at 05:47:20PM -0700, Tristan Schmelcher wrote: > FYI, the Ubuntu bug report is > https://bugs.launchpad.net/ubuntu/+source/vnc4/+bug/819473 > > On Fri, Sep 2, 2011 at 3:29 PM, Tristan Schmelcher > <tristan_schmelc...@alumni.uwaterloo.ca> wrote: > > Package: vnc4 > > Version: 4.1.1+X4.3.0-37 > > Severity: normal > > Tags: patch > > User: ubuntu-de...@lists.ubuntu.com > > Usertags: origin-ubuntu oneiric ubuntu-patch > > > > > > I have been experiencing this bug for several years but I finally decided > > to investigate it. I run Xvnc through xinetd and I often find that there > > are left-over Xvnc processes each consuming 100% CPU. They tend to crop up > > when a client disconnects. In particular, scanning ports with nmap produces > > the problem every time. > > > > I've tracked down the problem and implemented a fix. The issue is that Xvnc > > in inetd mode detects whether it is run as "wait" or "nowait" by checking > > if the inetd socket has a valid peer name with getpeername(). If it has a > > valid peer name then it assumes nowait mode, otherwise it assumes wait > > mode. But this is unreliable, because if it is run in nowait mode and a > > client connects and disconnects very quickly then the socket will no longer > > have a valid peer name when Xvnc checks and it will mistakenly use wait > > mode. The 100% CPU results from repeatedly trying to call accept() on the > > socket in the select loop. > > > > My solution is to instead detect wait vs. nowait via getsockopt(..., > > SOL_SOCKET, SO_ACCEPTCONN, ...), which works reliably in both modes. > > > > *** /tmp/tmpkCQys0 > > I have sent the attached patch to Ubuntu, but I am sending it to Debian too > > because there is nothing Ubuntu-specific about it. > > > > > > * Fix 100% CPU hang when run from inetd in nowait mode if a client > > connects and disconnects quickly (e.g., nmap). > > > > > > Thanks for considering the patch. > > > > > > -- System Information: > > Debian Release: squeeze/sid > > APT prefers natty-updates > > APT policy: (500, 'natty-updates'), (500, 'natty-security'), (500, 'natty') > > Architecture: amd64 (x86_64) > > > > Kernel: Linux 2.6.38-10-generic (SMP w/8 CPU cores) > > Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8) > > Shell: /bin/sh linked to /bin/dash > > > > > -- --------------------- Ola Lundqvist --------------------------- / o...@debian.org Annebergsslingan 37 \ | o...@inguza.com 654 65 KARLSTAD | | http://inguza.com/ +46 (0)70-332 1551 | \ gpg/f.p.: 7090 A92B 18FE 7994 0C36 4FE4 18A1 B1CF 0FE5 3DD9 / --------------------------------------------------------------- -- To UNSUBSCRIBE, email to debian-bugs-dist-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org
