When running an Extract/Load pipeline with Meltano, what's the best way (or ways) to kill a running job?
Generally these would be run via Airflow but would be nice to have a process that worked also with bare meltano elt and/or meltano run invocations from orphaned terminal sessions, which might not be able to be canceled simply by hitting Ctrl+C.
I am using gearman and supervisor to manage my worker processes. I have a case where I need to stop/restart supervisor without affecting the currently running processes.
e.g. I have configured the numprocs value in supervisor conf file as 2. I start supervisor and have 2 processes running.
Now I want to restart supervisor, such that the number of processes becomes 4, where supervisor controls only the two new processes. Is there a way this can be done.
I tried renaming the sock file before restarting. It didn’t work. I am using Amazon Linux.
EDIT
I will just elaborate more on what I am doing. I have some worker processes for gearman which are managed by supervisor. It works fine, but when I restart supervisor, the workers are killed and new workers are launched even if the workers are busy processing a job. So, I lose all the work done by processes.
So, I am using php-pcntl to intercept the signals produced by supervisor and then exit after the job is finished. This seems to be working well.
I send the interrupts like the following:
supervisorctl signal SIGTERM all
and then in my worker code, I have the following.
public static function work(GearmanWorker $gw){
pcntl_signal(SIGTERM, function($sig){
exit;
});
while(true){
$gw->work();
// Calls signal handlers for pending signals
pcntl_signal_dispatch();
}
}
Now, when I update my worker code, I should restart supervisor. But, if I directly restart, then even with the above implementation, all the processes are terminated. I want to avoid terminating the old prcoesses as they will quit by themselves when pcntl_signal_dispatch(); is called.
I want to set a cron job in ubuntu with this job
I have a python webscraping program which needs to be scrapped continuously after the program is terminated. In other words the flow is like this
If program is terminated, set the cron job again (until infinity)
Can this be done?
thanks
I have a job running using Hadoop 0.20 on 32 spot instances. It has been running for 9 hours with no errors. It has processed 3800 tasks during that time, but I have noticed that just two tasks appear to be stuck and have been running alone for a couple of hours (apparently responding because they don't time out). The tasks don't typically take more than 15 minutes. I don't want to lose all the work that's already been done, because it costs me a lot of money. I would really just like to kill those two tasks and have Hadoop either reassign them or just count them as failed. Until they stop, I cannot get the reduce results from the other 3798 maps!
But I can't figure out how to do that. I have considered trying to figure out which instances are running the tasks and then terminate those instances, but
I don't know how to figure out which instances are the culprits
I am afraid it will have unintended effects.
How do I just kill individual map tasks?
Generally, on a Hadoop cluster you can kill a particular task by issuing:
hadoop job -kill-task [attempt_id]
This will kill the given map task and re-submits it on an different
node with a new id.
To get the attemp_id navigate on the Jobtracker's web UI to the map task
in question, click on it and note it's id (e.g: attempt_201210111830_0012_m_000000_0)
ssh to the master node as mentioned by Lorand, and execute:
bin/hadoop job -list
bin/hadoop job –kill <JobID>
In a UNIX-y way, I'm trying to start a process, background it, and tie the lifetime of that process to my shell.
What I'm talking about isn't simply backgrounding the process, I want the process to be sent SIGTERM, or for it to have an open file descriptor that is closed, or something when the shell exits, so that the user of the shell doesn't have to explicitly kill the process or get a "you have running jobs" warning.
Ultimately I want a program that can run, uniquely, for each shell and carry state along with that shell, and close when the shell closes.
IBM's DB2 console commands work this way. When you connect to the database, it spawns a "db2bp" process, that carries the database state and connection and ties it to your shell. You can connect in multiple different terminals or ssh connections, each with its own db2bp process, and when those are closed the appropriate db2bp process dies and that connection is closed.
DB2 queries are then started with the db2 command, which simply hands it off to the appropriate db2bp process. I don't know how it communicates with the correct db2bp process, but maybe it uses the tty device connected to stdin as a unique key? I guess I need to figure that out too.
I've never written anything that does tty manipulation, so I have no clue where to even start. I think I can figure the rest out if I can just spawn a process that is automatically killed on shell exit. Anyone know how DB2 does it?
If your shell isn't a subshell, you can do the following; Put the following into a script called "ttywatch":
#!/usr/bin/perl
my $p=open(PI, "-|") || exec #ARGV; sleep 5 while(-t); kill 15,$p;
Then run your program as:
$ ttywatch commandline... & disown
Disowning the process will prevent the shell from complaining that there are running processes, and when the terminal closes, it will cause SIGTERM (15) to be delivered to the subprocess (your app) within 5 seconds.
If the shell isn't a subshell, you can use a program like ttywrap to at least give it its own tty, and then the above trick will work.
Okay, I think I figured it out. I was making it too complicated :)
I think all db2 is daemon-izing db2bp, then db2bp is calling waitpid on the parent PID (the shell's PID) and exiting after waitpid returns.
The communication between the db2 command and db2bp seems to be done via fifo with a filename based on the parent shell PID.
Waaaay simpler than I was thinking :)
For anyone who is curious, this whole endeavor was to be able to tie a python or groovy interactive session to a shell, so I could test code while easily jumping in and out of a session that would retain database connections and temporary classes / variables.
Thank you all for your help!
Your shell should be sending a SIGHUP signal to any running child processes when it shuts down. Have you tried adding a SIGHUP handler to your application to shut it down cleanly
when the shell exits?
Is it possible that your real problem here is the shell and not your process. My understanding agrees with Jim Lewis' that when the shell dies its children should get SIGHUP. But what you're complaining about is the shell (or perhaps the terminal) trying to prevent you from accidentally killing a running shell with active children.
Consider reading the manual for the shell or the terminal to see if this behavior is configurable.
From the bash manual on my MacBook:
The shell exits by default upon receipt of a SIGHUP. Before exiting, an interactive shell resends the SIGHUP
to all jobs, running or stopped. Stopped jobs are sent SIGCONT to ensure that they receive the SIGHUP. To
prevent the shell from sending the signal to a particular job, it should be removed from the jobs table with
the disown builtin (see SHELL BUILTIN COMMANDS below) or marked to not receive SIGHUP using disown -h.
If the huponexit shell option has been set with shopt, bash sends a SIGHUP to all jobs when an interactive
login shell exits.
which might point you in the right direction.