Re: [libvirt] [PATCH 2/2] qemu: use -incoming fd:n to avoid qemu holding fd indefinitely

On 12/22/2010 11:27 PM, Eric Blake wrote: > https://bugzilla.redhat.com/show_bug.cgi?id=620363 > > When using -incoming stdio or -incoming exec:cat, qemu keeps the > stdin fd open long after the migration is complete. Not to > mention that exec:cat is horribly inefficient, by doubling the > I/O and going through a popen interface in qemu. > > The new -incoming fd: of qemu 0.12.0 closes the fd after using > it, and allows us to bypass an intermediary cat process for > less I/O. > > It would also be possible to fix this bug for qemu< 0.12.0, by > creating a dummy 'cat' process that reads from real fd and writes to a > pipe, and pass the other end of the pipe into -incoming exec:cat or > -incoming stdio, at the expense of even more I/O. I don't know if > that is worth the patch, though. Since you are at it, you may also want to replace the usage of netcat and Unix sockets with "-incoming fd:" and a one-way pipe.