I've found autoserv's ability to start several remote commands, wait for one to
finish, and then kill the others (which is their expected lifecycle) somewhat
lacking.
My test scenario is this:
We have 4 programs: A, B, C, and D and 3 hosts: host1, host2, and host3 (the
hosts and programs are all connected over the network)
At T=0, start A on host1 and B on host2
At T=5, start C on host2
At T=7, start D on host3
When D finishes, B should also have finished, but A and C are daemons that
never normally finish.
A and C should now be killed, and the log files and stdout/stderr from all 4
programs must be retrieved and analyzed before determining whether the test
passes.
It appears that the best way to do this now is to start all the jobs in
subcommands and then use e.g. host2.run('kill %s' % B.remote_pid) to kill them,
and then suppress the abnormal termination error from the subcommand and fetch
the stdout and stderr through the result_pickle property of the subcommand.
I'd like to write subclass/reimplementation of subcommand which is host-aware,
so that the remote command can be controlled through the object, allowing the
stdout and stderr to be accessible while the command is executing, and so that
signals can be sent to the remote command.
I'm planning on adding a new global method "start_on_host(cmd, host)" that
returns a HostCommand object. This HostCommand object represents the remotely
executing command. It will have the following function:
- wait_for(timeout=None) #wait for the remote command to terminate,
at most the given timeout. If it's not done by them, forcibly kill it.
Timeout=0 means kill immediately, timeout=None means wait forever. It will
return the exit code of the process
- get_result() #get the CmdResult for the process, raise an exception
if the process is still running
- kill(signal=9) # send a signal to the remote command, default is kill
Also, while reading about paramiko, I read that it doesn't work properly in
fork()ed environments. Can anyone comment on how autotest is able to use
paramiko with subcommands?
I'm looking forward to your advice, experiences, and feedback :)
Thanks,
David
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