[R-SIG-Mac] Forking issues in Mavericks

[Simon Urbanek]

On Oct 29, 2013, at 3:53 PM, Jeroen Ooms <jeroen.ooms at stat.ucla.edu> wrote:

> On Tue, Oct 29, 2013 at 12:35 PM, Steve Lianoglou
> <lianoglou.steve at gene.com> wrote:
>> Is this happening when you are running R from w/in R.app (which, I
>> think, is not new), or are you running R from the terminal and still
>> seeing this)?
> 
> It happens when a forked child process tries to use some "fork unsafe"
> opratation, after the parent has already done so as well, see [1]. It
> is related to R.app in the sense that the GUI uses the CF event
> loop which is considered fork unsafe, and therefore a forked child
> process can't do any fork unsafe operations anymore. However it also
> happens in other contexts such as prefork in RApache [2].
> 
> But my actual question is: what is it about using httr::GET that is
> considered fork "unsafe", which was not considered unsafe in 10.8?
> 

I didn't have time to look (will do later today), but a wild guess is that Apple was moving away from some common libraries like OpenSSL and replacing them with their own which could be CF-based and thus unsafe. Again, that's wild guess, I'll have to look at the trace to confirm that.

Cheers,
Simon



> [1] http://objectivistc.tumblr.com/post/16187948939/you-must-exec-a-core-foundation-fork-safety-tale
> [2] http://stackoverflow.com/questions/2344368/problem-configuring-rapache-on-os-x-10-5-8/2358834#2358834
> 
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