Re: retry shm attach for windows (WAS: Re: OK, so culicidae is *still* broken)

On Mon, Jun 5, 2017 at 10:10 PM, Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
> Agreed. By the way, while browsing about this problem, I found that
> one other open source (nginx) has used a solution similar to what
> Andres was proposing upthread to solve this problem. Refer:
> https://github.com/nginx/nginx/commit/2ec8cfcd7d34415a99c3f3db3024ae954c00d0dd
>
> Just to be clear, by above, I don't mean to say that if some other
> open source is using some solution, we should also use it, but I think
> it is worth considering (especially if it is a proven solution - just
> saying based on the time (2015) it has been committed and sustained in
> the code).

I think the idea of retrying process creation (and I definitely agree
with Tom and Magnus that we have to retry process creation, not just
individual mappings) is a good place to start. Now if we find that we
are having to retry frequently, then I think we might need to try
something along the lines of what Andres proposed and what nginx
apparently did. However, any fixed address will be prone to
occasional failures (or maybe, on some systems, regular failures) if
that particular address happens to get claimed by something. I don't
think we can say that there is any address where that definitely won't
happen. So I would say let's do this retry thing first, and then if
that proves inadequate, we can also try moving the mappings to a range
where conflicts are less likely.

--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company