[libvirt] virsh migrate: sometimes command line cannot exit until manually press "ENTER" key
Hi, List, Do you meet the same problem? Host is kvm, doing: (e.g.) #virsh migrate sles11 qemu+ssh://147.2.207.55/system --live --unsafe password: Sometimes, VM is already running on the target host and disappears from source host, but the command line still hangs there, if pressing "ENTER", it will exit. I debugged the code, but found the result is weird. The code hangs at tools/virsh-domain.c -> cmdMigrate ->vshWatchJob->poll(): poll() is trying to select pipe_fd, which is used to receive message from doMigrate thread. In debugging, found that doMigrate finishes and at the end it does call safewrite() to write the retval ('0' or '1') to pipe_fd, and the write is completed. But cmdMigrate poll() cannot get the event. Then after pressing "ENTER" key, poll() can get the event and select pipe_fd, then command line can exit. Any ideas about the possible reason? Thanks, Chunyan
On Thu, Aug 7, 2014 at 11:02 AM, Chun Yan Liu <cyliu@suse.com> wrote:
Hi, List,
Do you meet the same problem? Host is kvm, doing: (e.g.) #virsh migrate sles11 qemu+ssh://147.2.207.55/system --live --unsafe password: Sometimes, VM is already running on the target host and disappears from source host, but the command line still hangs there, if pressing "ENTER", it will exit.
I debugged the code, but found the result is weird. The code hangs at tools/virsh-domain.c -> cmdMigrate ->vshWatchJob->poll(): poll() is trying to select pipe_fd, which is used to receive message from doMigrate thread. In debugging, found that doMigrate finishes and at the end it does call safewrite() to write the retval ('0' or '1') to pipe_fd, and the write is completed. But cmdMigrate poll() cannot get the event. Then after pressing "ENTER" key, poll() can get the event and select pipe_fd, then command line can exit.
Any ideas about the possible reason?
It is because, the authentication thread is independently waiting for the password on virsh. I see that the virWatchJob interferes with authentication thread and the password is never taken successfully. The virWatchJob probably needs to wait till the authentication thread completes taking the password after which it should start watching the job. Moreover, I see that --p2p migration doesnt work at all when auto login is not configured.
Thanks, Chunyan
-- libvir-list mailing list libvir-list@redhat.com https://www.redhat.com/mailman/listinfo/libvir-list
Thanks, Shiva
On 8/8/2014 at 12:18 AM, in message <CAAfHSJvP1P20kBFD9ZgYy=0JVvG5oiS0eVCfGZc+k39=EharkQ@mail.gmail.com>, Shivaprasad bhat <shivaprasadbhat@gmail.com> wrote: On Thu, Aug 7, 2014 at 11:02 AM, Chun Yan Liu <cyliu@suse.com> wrote: Hi, List,
Do you meet the same problem? Host is kvm, doing: (e.g.) #virsh migrate sles11 qemu+ssh://147.2.207.55/system --live --unsafe password: Sometimes, VM is already running on the target host and disappears from source host, but the command line still hangs there, if pressing "ENTER", it will exit.
I debugged the code, but found the result is weird. The code hangs at tools/virsh-domain.c -> cmdMigrate ->vshWatchJob->poll(): poll() is trying to select pipe_fd, which is used to receive message from doMigrate thread. In debugging, found that doMigrate finishes and at the end it does call safewrite() to write the retval ('0' or '1') to pipe_fd, and the write is completed. But cmdMigrate poll() cannot get the event. Then after pressing "ENTER" key, poll() can get the event and select pipe_fd, then command line can exit.
Any ideas about the possible reason?
It is because, the authentication thread is independently waiting for the password on virsh. I see that the virWatchJob interferes with authentication thread and the password is never taken successfully. The virWatchJob probably needs to wait till the authentication thread completes taking the password after which it should start watching the job.
Agree. Although in my testing password can be taken successfully, and I don't know how to explain why pressing "ENTER" then poll() can get the pipe_fd event, I do think both authentication thread and main process uses stdin might have some bad affect. I'd like to adjust the code a little to move the authentication before poll(). Thanks!
Moreover, I see that --p2p migration doesnt work at all when auto login is not configured.
Thanks, Chunyan
-- libvir-list mailing list libvir-list@redhat.com https://www.redhat.com/mailman/listinfo/libvir-list
Thanks, Shiva
participants (2)
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Chun Yan Liu -
Shivaprasad bhat