Expectations on when GC is called
- From: Saptarshi Guha <saptarshi.guha@xxxxxxxxx>
- To: luajit@xxxxxxxxxxxxx
- Date: Thu, 6 Mar 2014 09:14:50 -0800
This is a question about when GC is triggered. I'm calling Lua from another
language. The flow (hopefully this is clear) is this
1. R calls C through the .Call interface
2. The C code calls my lua code (snippet)
status = lua_pcall(L, narg, 1, base);
What this Lua code might do is create an object in the R language. In
this
language, one needs to 'protect' the variable from R' GC engine and then
when
returning back to R, 'unprotect' this. What I did was (for example)
M = function()
myObj = createRObject()
myObj = functionToProtect(myObj)
mObj = ffi.gc( myObject, functionToUnProtect)
-- do something
return nil
So when the lua code returns to C(after the pcall), i call
lua_gc(L, LUA_GCCOLLECT, 0);
to trigger the GC. I expect the lua GC to run and myObj to be collected
and
functionToUnProtect to be run.
However nothing is printed.
If i repeat steps (1) and (2) again, then it does get collected.
So, my question
1. Doesn't lua_gc call the GC?
2. If so, do i have expectations on the time bounds or ordering of
collections?
I hope i've been clear, my apologies if not
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