From: KOSAKI Motohiro <kosaki.motohiro@...>
Date: 2012-06-07T05:17:46+09:00
Subject: [ruby-core:45450] Re: [ruby-trunk - Feature #2715] Optimization to avoid spawning shell in Kernel#system call should check for failure conditions

(6/5/12 3:55 PM), akr (Akira Tanaka) wrote:
>
> Issue #2715 has been updated by akr (Akira Tanaka).
>
>
>> As akr-san described, some shells have tail invocation optimization. Thus, even if ruby doesn't have shell invocation optimization, caller can't assume that spawned process is neither child nor grand child.
>
> If we have shell invocation optimization (as now) and the command line is
> simple, the command is spawned as a child process.
>
> So removing the optimization breaks a program which assumes this behavior.
>
> For example, IO.popen("foo bar") {|io| ... Process.kill sig, io.pid ... }
> will be broken by removing the optimization.
>
> I feel this is incompatible enough.

.... I realized IO.pid is crazy mistaken feature. It wouldn't work when using
complex cmdline even if we will not remove the optimization. Sigh. (+_+