[erlang-questions] managing OS processes

Anthony Molinaro anthonym@REDACTED
Sun May 27 00:00:48 CEST 2012

I've found a need for this sort of thing as well.  +1 for getting something
into OTP itself.   I'm sure the real issue will be with Windows, although
I believe there was some code in couchdb for doing some control of windows
processes, and maybe erlexec already supports Windows?  Anyway, I can't
say I'd do much other than testing, but just wanted to voice my support.


On Sat, May 26, 2012 at 09:52:32PM +0100, Tim Watson wrote:
> I'm also working on very similar requirements in
> https://github.com/nebularis/systest/blob/master/src/systest_cli.erl
> and like you two, I have to rely on a combination of open_port with
> its constituent events and os:cmd/1 in order to SIGHUP/SIGKILL which
> feels rather 'hackish' to me. I've also noticed that it makes consumer
> code rather timing dependent, which is frustrating.
> I would be willing to participate in either
> (a) improving the built in port functionality or
> (b) working on erlexec
> Although C I'm fairly comfortable with, but C++ (which erlexec appears
> to be written in) isn't really my bag. I do have to ask though, is
> erlexec in need of much additional work? I also have 'client' modules
> for the OTP slave and ssh modules and don't want to invest a mountain
> of time in replacing open_port, but a little TLC to bring erlexec up
> to scratch would be time well spent if it would give a more consistent
> interface. In particular I have some issues with open_port based code
> with now such as
> 1. cli clients my code launches can be 'detached' (usually erlang
> nodes run with -detached or scripts that launch erlang nodes using `sh
> -C` or setsid/nohup and the like), which makes the port handling code
> both complex and messy.
> 2. some client code I'm testing will execute another (different)
> script/command to shut down the node and the listening port doesn't
> always get the exit status properly
> 3. signal handling is a mess
> So erlexec does sound promising, but IMO it would be *better* if the
> built in open_port functionality could be extending to deal with these
> situations properly.
> Cheers,
> Tim
> On 26 May 2012 13:12, Gleb Peregud <gleber.p@REDACTED> wrote:
> > On Sat, May 26, 2012 at 11:06 AM, Benoit Chesneau <bchesneau@REDACTED> wrote:
> >> I'm trying to find a way to manage some os processes launched from
> >> Erlang. For example I need to relaunch them when the external process
> >> die for an unknown reason or send an HUP signal or just stop the
> >> external process.
> >
> > Hello Benoit
> >
> > Looks like there are two of us, who needs a better mechanism to manage
> > OS processes from Erlang. I need it for a CI server which I'm working
> > on, so my requirements are not as high as yours, but still os:cmd
> > doesn't work for me and ports are missing one feature which I need.
> >
> > Maybe we could reanimate erlexec together?
> >
> > Cheers,
> > Gleb
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Anthony Molinaro                           <anthonym@REDACTED>

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