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I couldn't fully understand your post, but I think I understand the error message and "hook".

Lua can only yield if the C call stack is empty. This means you cannot yield from inside a metamethod, eg __index, or from a nested C call, or, in this case, from a hook. If you really require this, you need a dedicated C stack for all lua threads, eg you need coco.

This solution increases memory usage somewhat. Future versions of jit promise a better approach if IIRC.

- Alex

----- Original Message ----- From: "Joseph Saadé" <>
To: <>
Sent: Thursday, March 13, 2008 6:19 PM
Subject: lua threads resuming and yielding from C

In my game project every entity has a different script running in a
new lua thread.
Every game loop, the engine calls the function OnUpdate located in every script.
I want the ability to pause a script.
I implemented that by using a script manager that keeps track if a
script is yield.
so somthing like this would work:

function OnUpdate(dt)

Entity.Pause is a C hook function that pauses the thread execution
using lua_yield.
the script engine waits 3 seconds and then calls lua_resume.

The function OnUpdate is not called while is script is yielding.
my problem is that after the script first resumes, the doAI2() is not
called, nothing after the pause command is actually called. and the
next call to yield/resume will resolve in an error (yield returns:
"attempt to yield across metamethod/c-call boundary")

so can't i yield a thread from inside a hook function and resume it's
execution normally?