Long-time users of Houdini will notice that we've turned off threaded UI by default in the 9.1 release. The reason this is required is because X, the graphical system on Linux, has a bug in the latest releases that causes hangs when you're using threads with X.
Non-technical/non-Linux people, feel free to skip this paragraph: For those who want to know, it's libX11's 1.1 release, which builds libX11 on top of XCB, the new low-level X library and protocol. There seems to be several deadlocks involved in waiting for responses from the X server. Downgrading to a version of libX11 not built on XCB, for example libX11 1.0.3, fixes this hang. I don't know how likely it is that you will be able to downgrade, though. If you can, everything should work normally - libX11 is backwards/forwards compatible.
There is a bug reported [bugs.freedesktop.org] with the relevant people. If you have a support contract with SUSE/Novell or Ubuntu, and you want this fixed, now's the time.
Probably number one with a bullet is the escape button vs the popup idialog - and the speed at which you can interrupt that DOPs sim when you realize you put in 22000 instead of 220.
Other than that, there are some that feel interactivity is faster. Other's may chime in with other things that escape me at the moment. Overall it's not unusable without it, but it's nicer.
I am curious though. What exactly is a “hang”? Is this another way of saying you'll get segmentation faults? I've been using Gutsy without the environment var for a while now, and the only crashes I get are X11 related seg faults.
Is it difficult to replace my current libX11 with the older one? if it's more difficult then setting up a symlink I'll probably pass and go with the environment variable.
A hang means that the program becomes completely non-responsive, which is just as bad as a crash (possibly even worse for Houdini, as it won't save a hip file to /tmp for you). It is more commonly found in threaded code, which is why turning off threaded UI tends to solve the problem.
Apparently libX11's 1.1 release can be compiled with or without XCB enabled, and everything I've found so far says that both Ubuntu 7.04 and 7.10 have it disabled by default. Possibly due to issues it causes with java.
I also read that the latest, currently beta Ubuntu Hardy does have XCB enabled.
Actually, I was just poking around this issue - is it possible to disable XCB in the current X session via Xorg.conf, and if so does it make the problem go away?
It's a little disheartening to read some of the numerous threads out there where users are having apps crash and have tracked it to XCB and the response back is always “we have determined there are no bugs - you're threading incorrectly”. The finger pointing begins…
I'll volunteer to be a guinea pig and recompile libx without xcb support somewhere next week…then see what happens…
When reading the docs about xcb I get the impression it's sort of an add-on/plugin for xlib to improve xlib by giving it a smaller “footprint” (a bit like what dietlibc does). Libx should work without xcb though :roll:
I may be wrong but I believe that effectively that test has already been done by downgrading the X11 to the version before XCB - which is easier than recompiling X…. However, I suppose that would put the nail in the coffin and determine that it's *definitely* that, and not something else.
Ubuntu 7.10 has libX11 rel 2:1.1.1 compiled without XCB by default and there are no “hangs” with a threaded GUI, so compiling it without should definitely work.
Sorry for the old bump…I've noticed that about a month ago the FCB guys claim to have fixed this ongoing problem according to the bug link posted above by Joe. I know you guys have been burning on the Mac and the next release, but has anyone had a chance to download/compile a test to see if it actually works with multithreaded UI?
I am running one of those distro's that always upgrade to the newest bleeding edge packages (and by doing so break quite a few things now and then - gcc 4.3.0 will be fun with the HDK, i can tell you that) so i'll enable threading once the update hits the repository and then i'll see if we can get past the splash screen.
Oh, does anyone have a wacom tablet on an amd64 system and houdini that doesn't crash X? What's your secret, i really want to know! (Yes OSS/Linux can suck sometimes).
Pagefan Oh, does anyone have a wacom tablet on an amd64 system and houdini that doesn't crash X? What's your secret, i really want to know! (Yes OSS/Linux can suck sometimes).
Yes. Wacom Intuos3 A5 wide on dual Xeon with ubuntu 7.10 64 bit, GeForce8800GTS, H9.1 runs with no problems.
