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?