On Sun, May 24, 2009 at 9:16 PM, Michael Goldish <mgoldish@xxxxxxxxxx> wrote:
> VM.create() does a few things (such as finding free ports) which are not safe
> to execute in parallel. Use a lock file to make sure this doesn't happen. The
> lock is released only after the VM is started or fails to start.
>
> Signed-off-by: Michael Goldish <mgoldish@xxxxxxxxxx>
> ---
> client/tests/kvm_runtest_2/kvm_vm.py | 85 +++++++++++++++++++---------------
> 1 files changed, 48 insertions(+), 37 deletions(-)
>
> diff --git a/client/tests/kvm_runtest_2/kvm_vm.py b/client/tests/kvm_runtest_2/kvm_vm.py
> index 3ce2003..af06693 100644
> --- a/client/tests/kvm_runtest_2/kvm_vm.py
> +++ b/client/tests/kvm_runtest_2/kvm_vm.py
> @@ -3,6 +3,7 @@
> import time
> import socket
> import os
> +import fcntl
>
> import kvm_utils
> import kvm_log
> @@ -289,48 +290,58 @@ class VM:
> kvm_log.error("Actual MD5 sum differs from expected one")
> return False
>
> - # Handle port redirections
> - redir_names = kvm_utils.get_sub_dict_names(params, "redirs")
> - host_ports = kvm_utils.find_free_ports(5000, 6000, len(redir_names))
> - self.redirs = {}
> - for i in range(len(redir_names)):
> - redir_params = kvm_utils.get_sub_dict(params, redir_names[i])
> - guest_port = int(redir_params.get("guest_port"))
> - self.redirs[guest_port] = host_ports[i]
> -
> - # Find available VNC port, if needed
> - if params.get("display") == "vnc":
> - self.vnc_port = kvm_utils.find_free_port(5900, 6000)
> -
> - # Make qemu command
> - qemu_command = self.make_qemu_command()
> + # Make sure the following code is not executed by more than one thread
> + # at the same time
> + lockfile = open("/tmp/kvm-autotest-vm-create.lock", "w+")
How do you handle an open failure?
> + fcntl.lockf(lockfile, fcntl.LOCK_EX)
What if other instance has locked the file at the moment. Definitely
you would not like to fail. You may want to wait for a while and try
agian. I feel the default behaviour should be a blocking one but still
you want to print the debug message
kvm_log.debug("Trying to acquire lock for port selection")
before getting the lock.
>
> - # Is this VM supposed to accept incoming migrations?
> - if for_migration:
> - # Find available migration port
> - self.migration_port = kvm_utils.find_free_port(5200, 6000)
> - # Add -incoming option to the qemu command
> - qemu_command += " -incoming tcp:0:%d" % self.migration_port
> + try:
> + # Handle port redirections
> + redir_names = kvm_utils.get_sub_dict_names(params, "redirs")
> + host_ports = kvm_utils.find_free_ports(5000, 6000, len(redir_names))
> + self.redirs = {}
> + for i in range(len(redir_names)):
> + redir_params = kvm_utils.get_sub_dict(params, redir_names[i])
> + guest_port = int(redir_params.get("guest_port"))
> + self.redirs[guest_port] = host_ports[i]
> +
> + # Find available VNC port, if needed
> + if params.get("display") == "vnc":
> + self.vnc_port = kvm_utils.find_free_port(5900, 6000)
> +
> + # Make qemu command
> + qemu_command = self.make_qemu_command()
> +
> + # Is this VM supposed to accept incoming migrations?
> + if for_migration:
> + # Find available migration port
> + self.migration_port = kvm_utils.find_free_port(5200, 6000)
> + # Add -incoming option to the qemu command
> + qemu_command += " -incoming tcp:0:%d" % self.migration_port
> +
> + kvm_log.debug("Running qemu command:\n%s" % qemu_command)
> + (status, pid, output) = kvm_utils.run_bg(qemu_command, None, kvm_log.debug, "(qemu) ")
> +
> + if status:
> + kvm_log.debug("qemu exited with status %d" % status)
> + kvm_log.error("VM could not be created -- qemu command failed:\n%s" % qemu_command)
> + return False
>
> - kvm_log.debug("Running qemu command:\n%s" % qemu_command)
> - (status, pid, output) = kvm_utils.run_bg(qemu_command, None, kvm_log.debug, "(qemu) ")
> + self.pid = pid
>
> - if status:
> - kvm_log.debug("qemu exited with status %d" % status)
> - kvm_log.error("VM could not be created -- qemu command failed:\n%s" % qemu_command)
> - return False
> -
> - self.pid = pid
> + if not kvm_utils.wait_for(self.is_alive, timeout, 0, 1):
> + kvm_log.debug("VM is not alive for some reason")
> + kvm_log.error("VM could not be created with command:\n%s" % qemu_command)
> + self.destroy()
> + return False
>
> - if not kvm_utils.wait_for(self.is_alive, timeout, 0, 1):
> - kvm_log.debug("VM is not alive for some reason")
> - kvm_log.error("VM could not be created with command:\n%s" % qemu_command)
> - self.destroy()
> - return False
> + kvm_log.debug("VM appears to be alive with PID %d" % self.pid)
>
> - kvm_log.debug("VM appears to be alive with PID %d" % self.pid)
> + return True
>
> - return True
> + finally:
> + fcntl.lockf(lockfile, fcntl.LOCK_UN)
> + lockfile.close()
>
> def send_monitor_cmd(self, command, block=True, timeout=20.0):
> """Send command to the QEMU monitor.
> --
> 1.5.4.1
>
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--
Sudhir Kumar
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