tt>"bad callback"</tt>. Then you'll need to manually turn off
JIT-compilation with
<a href="ext_jit.html#jit_onoff_func"><tt>jit.off()</tt></a> for the
surrounding Lua function that invokes such a message polling function (or
similar).
</p>

<h3 id="callback_resources">Callback resource handling</h3>
<p>
Callbacks take up resources &mdash; you can only have a limited number
of them at the same time (500&nbsp;-&nbsp;1000, depending on the
architecture). The associated Lua functions are anchored to prevent
ga