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Lanes is a lightweight, native, lazy evaluating multithreading library for Lua 5.1 and 5.2.

README
=====================
  Usage on Windows:
=====================

For once, Win32 thread prioritazion scheme is actually a good one, and
it works. :)  Windows users, feel yourself as VIP citizens!!

-------------------
  Windows / MSYS:
-------------------

On MSYS, 'stderr' output seems to be buffered. You might want to make
it auto-flush, to help you track & debug your scripts. Like this:

    io.stderr:setvbuf "no"

Even after this, MSYS insists on linewise buffering; it will flush at
each newline only.


===================
  Usage on Linux:
===================

Linux NTPL 2.5 (Ubuntu 7.04) was used in the testing of Lua Lanes.

This document (http://www.icir.org/gregor/tools/pthread-scheduling.html)
describes fairly well, what (all) is wrong with Linux threading, even today.

For other worthy links:
    http://kerneltrap.org/node/6080
    http://en.wikipedia.org/wiki/Native_POSIX_Thread_Library

In short, you cannot use thread prioritation in Linux. Unless you run as
root, and I _truly_ would not recommend that. Lobby for yet-another thread
implementation for Linux, and mail -> akauppi@gmail.com about it. :)

CAVEAT: Anyone sufficiently knowledgeable with pthread scheduling is free to
contact me bnt DOT germain AT gmail DOT com)  with a suitable edit
if this no longer applies on more recent kernels.


======================
  Usage on Mac OS X:
======================

No real problems in OS X, _once_ everything is set up right...

In short, have your Lua core compiled with LUA_USE_DLOPEN and LUA_USE_POSIX
instead of the (default as of 5.1) LUA_DL_DYLD and LUA_USE_MACOSX. This is
crucial to have each module loaded only once (even if initialized separately
for each thread) and for the static & global variables within the modules to
actually be process-wide. Lua Lanes cannot live without...
Lua 5.2 is fine in that regard (check luaconf.h to be safe).

Another issue is making sure you only have _one_ Lua core. Your 'lua' binary
must link dynamically to a .dylib, it must _not_ carry a personal copy of Lua
core with itself. If it does, you will gain many mysterious malloc errors
when entering multithreading realm.

<<
lua-xcode2(9473,0xa000ed88) malloc: ***  Deallocation of a pointer not malloced: 0xe9fc0; This could be a double free(), or free() called with the middle of an allocated block; Try setting environment variable MallocHelp to see tools to help debug
<<

rm lua.o luac.o
gcc -dynamiclib -install_name /usr/local/lib/liblua.5.1.dylib \
    -compatibility_version 5.1 -current_version 5.1.2 \
    -o liblua.5.1.2.dylib *.o

gcc -fno-common -DLUA_USE_POSIX -DLUA_USE_DLOPEN -DLUA_USE_READLINE -lreadline -L. -llua.5.1.2 lua.c -o lua

That should be it. :)

Fink 'lua51' packaging has the necessary changes since 5.1.2-3.


=====================
  Usage on FreeBSD:
=====================

Unlike in Linux, also the Lua engine used with Lanes needs to be compiled with
'-lpthread'. Otherwise, the following malloc errors are received:

    <<
    lua in free(): warning: recursive call
    PANIC: unprotected error in call to Lua API (not enough memory)
    <<

Here are the Lua compilation steps that proved to work (FreeBSD 6.2 i386):

    gmake freebsd
    rm lua.o luac.o liblua.a
    gcc -shared -lm -Wl,-E -o liblua.5.1.2.so *.o
    gcc -O2 -Wall -DLUA_USE_LINUX -lm -Wl,-E -lpthread -lreadline -L. -llua.5.1.2 lua.c -o lua

To compile Lanes, use 'gmake' or simply:

    cc -O2 -Wall -llua.5.1.2 -lpthread -shared -o out/bsd-x86/lua51-lanes.so \
        -DGLUA_LUA51 gluax.c lanes.c

To place Lua into ~/local, set the following environment variables (this is
just a reminder for myself...):

    export CPATH=.../local/include
    export LIBRARY_PATH=.../local/lib
    export LD_LIBRARY_PATH=.../local/lib

=======================
  Manual installation
=======================

After running GNU make, in directory `src` you will find files
`lanes.lua` and `lanes/core.so`.  The first goes into a directory on
your LUA_PATH, and the `lanes` directory goes into a directory on your
LUA_CPATH.  If you are not sure how this works, try creating

   /usr/local/share/lua/5.1/lanes.lua
   /usr/local/lib/lua/5.1/lanes/core.so

=======================
  Note about LuaJIT
=======================
By default LuaJIT2 provides an non-thread-safe memory allocator to improve performance.
Of course this will break when running several Lua states concurrently.
Don't forget to initialize Lanes with the 'protect_allocator' option (see documentation)
if you experience random crash issues.

(end)
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