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Date: Sat, 30 Nov 2019 07:14:05 +0300
From: Konstantin Osipov <kostja.osipov@gmail.com>
Message-ID: <20191130041405.GB31199@atlas>
References: <20191128204512.19732-1-gorcunov@gmail.com>
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Subject: Re: [Tarantool-patches] [PATCH 1/5] popen: Introduce a backend
	engine
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To: Cyrill Gorcunov <gorcunov@gmail.com>
Cc: tml <tarantool-patches@dev.tarantool.org>

* Cyrill Gorcunov <gorcunov@gmail.com> [19/11/30 07:03]:
> Once we sart using non-blocking IO the read() could return -EAGAIN.
> I think I need to find out how python is handling this situation,
> is their read is blocking or not.

Take a look at how coio works. It adds the descriptor to the event
loop and yields the current fiber.

> 
> The eio reaps children itself, ie calls for wait. Thus imagine a situation,
> we start killing the process like
> 
> popen_kill(handle)
> 	...
> 	kill(handle->pid)
> 	...
> 
> but before we reach kill() this process exited by self or killed
> by a user on the node. The signal handler sets pid = -1 and we
> call kill(-1). Which is wrong of course.

Can't you check the pid > 0 before you send the signal?

-- 
Konstantin Osipov, Moscow, Russia