Re: Why sweep userdata list "g->finobj" during sweep phase?

["Cezary H. Noweta" <chn@...>]

Hello,

On 2016-01-23 05:00, Wei John wrote:

> Lua version is 5.2.4.

> During GC sweep phase, when finish sweeping string,
> GC switch to sweep userdata list:"g->finobj".
> But all the white userdatas having "__gc" tag method are
> separated to list "g->tobefnz" by function "separatetobefnz()"
> during atomic phase, so there no white userdatas in "g->finobj"
> after atomic.
> What is the reason for GCSsweepudata、sweepfin ?

,,sweepfin'' is used as described: ,,current position of sweep in list 
'finobj'''. For example, in the incremental mode, gc marks objects as 
white while in a sweep step -- quite well that there are no whites after 
atomic -- however, thanks to ,,sweepfin'', all udatas in ,,finobj'' are 
white after sweep:

1. Move all whites from ,,finobj'' to ,,tobefnz'' (now, there are no 
whites in ,,finobj'').
2. (Un)Mark remaining ,,finobj''s as whites (here ,,sweepfin'' is used).

Sweeping is for un-marking objects not only for releasing them 
(http://www.brpreiss.com/books/opus5/html/page424.html).

-- best regards

Cezary H. Noweta