Long ago, I submitted an issue: https://github.com/kimchi-project/kimchi/issues/1170 ... Test by following script: import subprocess import os import time def _check_remote_libvirt_conn(remote_host,         user='root', transport='ssh'):     FNULL = open(os.devnull, 'w')     dest_uri = 'qemu+%s://%s@%s/system' % (transport, user, remote_host)     cmd = ['virsh', '-c', dest_uri, 'list']     proc = subprocess.Popen(cmd, stdout=FNULL, stderr=FNULL,             shell=True, preexec_fn=os.setsid)     timeout = 0     while proc.poll() is None:         time.sleep(1)         timeout += 1         if timeout == 5:             print("killed")             os.killpg(os.getpgid(proc.pid), signal.SIGTERM) if __name__ == '__main__':     _check_remote_libvirt_conn('localhost') `proc` is timeout every time although the connection is normal tested by `virsh -c <uri>` list The following is the reason of changing(From Python Document 2.7.14):  Do not use stdout=PIPE or stderr=PIPE with this function as that can deadlock based on the child process output volume. Use Popen with the communicate() method when you need pipes.  Using shell=True can be a security hazard. See the warning under Frequently Used Arguments for details. At the same time, if not change, it does not work. diff --git a/model/vms.py b/model/vms.py index 6da4f3b..92e771f 100644 --- a/model/vms.py +++ b/model/vms.py @@ -1885,10 +1885,11 @@ class VMModel(object):      def _check_remote_libvirt_conn(self, remote_host,                                     user='root', transport='ssh'): +        FNULL = open(os.devnull, 'w')          dest_uri = 'qemu+%s://%s@%s/system' % (transport, user, remote_host)          cmd = ['virsh', '-c', dest_uri, 'list'] -        proc = subprocess.Popen(cmd, stdout=subprocess.PIPE, -                                shell=True, preexec_fn=os.setsid) +        proc = subprocess.Popen(cmd, stdout=FNULL, stderr=FNULL, +                                shell=False, preexec_fn=os.setsid)          timeout = 0          while proc.poll() is None:              time.sleep(1) -- Regards River (Fu.Lin)