Re: [libvirt] [PATCH 3/3] Manually kill gzip if restore fails before starting qemu
On 01/25/2011 12:47 PM, Daniel P. Berrange wrote:
On Tue, Jan 25, 2011 at 04:24:20AM -0500, Laine Stump wrote:
> If a guest image is saved in compressed format, and the restore fails
> in some way after the intermediate process used to uncompress the
> image has been started, but before qemu has been started to hook up to
> the uncompressor, libvirt will endlessly wait for the uncompressor to
> finish, but it never will because it's still waiting to have something
> hooked up to drain its output.
>
> The solution is to manually send a SIGTERM to the compressor process
> before calling waitpid on it (only if the restore has failed, of
> course).
Are we leaking a file descriptor here then ? I would think
it would get EPIPE or EIO or an end-of-file if QEMU didn't
start up and automatically exit. That we need to kill it
seems odd (though a worthy extra measure once we're verified
that all FDs are closed properly).
Good point. I guess the proper thing to do is first close the fd that's
pointing to the pipe, then do the kill (which will probably be
unnecessary, but as you say a worthy extra measure).
Do you think it's necessary to do anything this complicated?
kill(pid, SIGTERM);
(usleep or maybe a waitpid(pid, &childstat, WNOHANG) ?)
if (kill(pid, 0) == 0)
kill(pid, SIGKILL);
Or is the single SIGTERM sufficient?