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Re: [Qemu-devel] [PATCH] qemu-char: Allow a chardev to reconnect if disc
From: |
Gerd Hoffmann |
Subject: |
Re: [Qemu-devel] [PATCH] qemu-char: Allow a chardev to reconnect if disconnected |
Date: |
Fri, 11 Apr 2014 09:08:03 +0200 |
Hi,
> > This patch is modified according to corey's patch. Some changes below:
> > 1. IMO it's unnecessary that chardev reconnect if it fails to connect at
> > startup.
> > Qemu exit in this scene. In this way the patch does not change interface of
> > chardev.
> > It would be much more simple.
>
> I believe that it should not stop qemu if it fails at startup.
> Otherwise you constrain the start order and you can prevent a server
> from coming up because of a missing resource that may not be that
> critical at the moment.
With reconnect being implemented (and active, guess we should add a
option for it) it we might rethink this indeed.
> With the current implementation, client sockets
> really aren't that useful for a critical system. Reconnecting makes it
> usable in a critical system.
I consider client sockets not very useful at all, I always put my
sockets into server mode. YMMV though.
> > 2. I set the reconnect timer one second, just like pty.
>
> I'm not too picky about the time. A couple of things about this:
Well, sockets and pty are different. pty is a local thing. sockets (at
least tcp) goes out to the network. After each failed reconnect the
time to retry should be increased a bit so you don't flood the
non-responding server with connect requests.
> With this patch, the default behavior changes to reconnect. That might
> cause issues for some users. Adding a configurable timeout is easy if
> you have to specify something on the command line, that's why I did it.
Specifying the timeout (best with min+max) could enable reconnect at the
same time, i.e. something like
-chardev socket,host=1.2.3.4,port=5678,reconnect=1-300
would turn on reconnect, with 1 second min and 300 seconds (5min) max
delay.
cheers,
Gerd