Multi-threading is not allowed

Fixed upstream in libxml2-2.7.6

libxml2-2.7.4 and 2.7.5 'configure' just contain a bug in the --with-threads configure option processing

This is a very serious bug since many apps rely on libxml2 in a threaded environment. I noticed this problem when using libstreamanalyzer on karmic. The configure option --with-threads should be added to the package to make sure this does not happen again easily.

This bug does not exist in 2.7.6 as used in Lucid, the ./configure script correctly uses threads by default.

This is mentioned in the upstream changelog for 2.7.6 http://people.canonical.com/~jriddell/tmp/libxml/

TEST CASE: with the old libxml2 run install strigi-utils

xmlindexer -j 5 /usr/include/ > /dev/null

it will crash

with the new libxml2 run it again. it won't crash

Uploaded to karmic-proposed, awaiting approval

Jos van den Oever wrote:
: configure option --with-threads should be added to the package to make sure this does not happen again easily

Jonathan Riddell wrote:
: libxml2_2.7.5.dfsg-1ubuntu1.1.debdiff (1.0 KiB, text/plain)

Please, don't make live harder! Explicit --with-threads won't add any value to safety against this kind of bugs. libxml2 intended to be multithreaded by default, therefore, breaking MT safety in default configuration (without any --{with,without}-threads option) noticed very fast. In contrast the bugs in explicit --with-threads handling may live unnoticed some long time.

Therefore, my proposal NOT to add --with-threads to the configure flags (which, for example, would not help you with libxml2-2.7.4), but just upgrade libxml2 package itself to 2.7.6 version.

If you anyway want to stay at libxml2-2.7.5 for any cost, then you need not to add yet another configure flag, but cherry-pick the appropriate patch from upstream:
    858084f Restore thread support in default configuration
    (http://git.gnome.org/browse/libxml2/commit/?id=858084fdec25a2617d626d0f65fac6c151136276)

For an SRU, an explicit --with-threads seems acceptable. It's fixed properly in lucid.

However, this seems to have a very high regression potential, since it could change the behaviour of the library in unexpected ways. Therefore this update needs some verification feedback with a standard GNOME and KDE session, as well as a server application (like PostgreSQL).

Accepted libxml2 into karmic-proposed, the package will build now and be available in a few hours. Please test and give feedback here. See https://wiki.ubuntu.com/Testing/EnableProposed for documentation how to enable and use -proposed. Thank you in advance!

Updated and compiled successfully an application that was complaining by this issue. Keeping it installed for feedback later...

No complaining in a week of using this version in a Desktop environment... Used GNOME, a MySQL server and virtualbox among other apps.

When will this be published in karmic ?

On Sunday 24 January 2010 22:46:57 Christoph Korn wrote:
> When will this be published in karmic ?

I dont know, i'm not a kubuntu developer.

Cheers,
Jos

Christoph Korn [2010-01-24 21:46 -0000]:
> When will this be published in karmic ?

Did you also test this update? I'd like to have more than one "works
for me" for such a central component.

Thanks,

Martin
--
Martin Pitt | http://www.piware.de
Ubuntu Developer (www.ubuntu.com) | Debian Developer (www.debian.org)

Martin, some feedback for you.

0 a.d.
http://wildfiregames.com/0ad/

Related bug ticket
http://trac.wildfiregames.com/ticket/432

Earlier today I attempted to build an open source RTS game under development called 0 a.d.
Using libxml2 and libxml2-dev ( 2.7.5.dfsg-1ubuntu1 ) from main Karmic repository to compile source of 0 a.d. would result with following error.

../../../source/tools/atlas/AtlasUI/Misc/DLLInterface.cpp:48:2: error: #error libxml2 must have threading support enabled
make[1]: *** [obj/AtlasUI_Debug/DLLInterface.o] Error 1
make: *** [AtlasUI] Error 2

libxml2 and libxml2-dev ( 2.7.5.dfsg-1ubuntu1.1 ) from Karmic-proposed fixed the issue.
I was able to compile 0 a.d. successfully with the updated libraries.

This bug was fixed in the package libxml2 - 2.7.5.dfsg-1ubuntu1.1

---------------
libxml2 (2.7.5.dfsg-1ubuntu1.1) karmic-proposed; urgency=low

  * Build using --with-threads, closes LP: #309149
 -- Jonathan Riddell <email address hidden> Mon, 28 Dec 2009 23:40:10 +0000