1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
|
[[meta copyright="Copyright © 2008, 2009 Free Software Foundation, Inc."]]
[[meta license="""[[toggle id="license" text="GFDL 1.2+"]][[toggleable
id="license" text="Permission is granted to copy, distribute and/or modify this
document under the terms of the GNU Free Documentation License, Version 1.2 or
any later version published by the Free Software Foundation; with no Invariant
Sections, no Front-Cover Texts, and no Back-Cover Texts. A copy of the license
is included in the section entitled
[[GNU_Free_Documentation_License|/fdl]]."]]"""]]
[[meta title="Convert Hurd Libraries and Servers to pthreads"]]
The Hurd was originally created at a time when the [pthreads
standard](http://www.opengroup.org/onlinepubs/009695399/basedefs/pthread.h.html)
didn't exist yet. Thus all Hurd servers and libraries are using the old
[[cthreads|hurd/libcthreads]] package that came with [[microkernel/Mach]],
which is not compatible with [[pthreads|hurd/libpthread]].
Not only does that mean that people hacking on Hurd internals have to deal with
a non-standard thread package, which nobody is familiar with. Although a
pthreads implementation for the Hurd was created in the meantime, it's not
possible to use both cthreads and pthreads in the same program. Consequently,
pthreads can't presently be used in any Hurd servers -- including translators.
Some work already has been done once on converting the Hurd servers and
libraries to use pthreads, but that work hasn't been finished. It is available
as [[GNU_Savannah_task 5487]] and can of course be used to base the new work
upon.
The goal of this project is to have all the Hurd code use pthreads. Should any
limitations in the existing pthreads implementation turn up that hinder this
transition, they will have to be fixed as well.
One possible option is creating a wrapper that implements the cthreads
interfaces on top of pthreads, to ease the transition -- but it might very well
turn out that it's easier to just change all the existing code to use pthreads
directly. This is up to the student. Such a wrapper has been proposed as
[[GNU_Savannah_task 7895]] and its implementation would be a useful
starting-point.
This project requires relatively little Hurd-specific knowledge. Experience
with multithreaded programming in general and pthreads in particular is
required, though.
Possible mentors: Samuel Thibault (youpi)
Exercise: Take some small piece of code using ctreads and convert it to
pthreads.
Note: Barry Defreese already has an almost complete patch: boring parts should
be mostly done, tricky parts are still missing.
|
