On 01/25/2011 12:47 PM, Daniel P. Berrange 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
On Tue, Jan 25, 2011 at 04:24:20AM -0500, Laine Stump wrote: 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?