[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