Any resources about threading problems?
billmedland at mercuryspeed.com
Fri Mar 4 10:52:44 CST 2005
On February 23, 2005 10:41 am, Mike Hearn wrote:
> On Wed, 23 Feb 2005 09:30:50 -0800, Bill Medland wrote:
> > Does anyone know any site or book or something with a decent discussion
> > about the problems of the different threading models and their
> > implementations?
> That'd be the developers guide ;)
Yes, it looks like it is on the way to becoming a canonical reference
> > In the Developer's Guide in section 8.3 there are references to "the
> > threading chapter". Is this a section that has not yet been written?
> It was written, and then the developer guide was reorganised and a ton of
> content was moved around. It's now under "NTDLL", which IMHO isn't very
> intuitive but I didn't reorganise it so I would say that :)
> > As I understand it we (in the pthreads version) "override the native
> > pthreads library". What does this mean?
> It's explained at the above URL.
> thanks -mike
OK. So I've spent over a week mulling over all this and I think I am
beginning to see the light, but I find our description confusing, primarily
due to confusion over terminology. I'd like to tighten it up and so I would
appreciate it if someone who knows this stuff can confirm I have understood
The source of a lot of my confusion is terminology.
pthread (or occasionally Pthread) is more normally used as a short name for
the Pthreads section of the POSIX standard, and is therefore a specification,
not an implementation. We frequently use it to mean both the specification
and any implementation that correctly implements the specification (such as
the NPTL and not Linuxthreads)
kthread has many meanings. It is sometimes a short name for a kernel thread
(an object in the kernel). Sometimes it refers to a simple threading package
with a very non-pthreads api, used in various computer science classes around
the world. I still don't understand what it means in our documentation, but
I presume it means LinuxThreads, LWP or any other threading implementation
that does not correctly implement the pthread api.
NPTL (Native POSIX Thread Library for Linux) is an implementation of the
pthread interface for the Linux operating system. It is the replacement for
Linuxthreads and is designed so that it can conform to the standard,
especially in areas where Linuxthreads does not.
Linuxthreads is "a simple clone()-based implementation of Posix threads for
Linux". However, being simple, it fails to conforn to the standard in
several areas. Major packages have worked around these failures in the past.
LWP is (for us) the lightweight process library, a library handling
multithreading primarily on SunOS, through its own api. This is not actually
relevant to our high-level description.
We talk about overriding the native pthreads library. Do we always override
it or is it only wine-kthread that overrides it? My understanding is that if
the underlying pthreads implementation correctly implements pthreads then it
is not overridden; we only override it if the pthreads implementation is
incorrect (e.g. if the implementation is Linuxthreads), and it only does so
for the wine processes.
Is that all correct?
(Then there's the whole question of when pthreads means the pthreads
specification, when it means the Linuxthreads implementation and when it
means the NPTL implementation. If I have the above correct then I can patch
up 18.104.22.168 and people can review the patch)
mailto:billmedland at mercuryspeed.com
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