I've got a Python script managing a gdb process on Windows, and I need to be able to send a SIGINT to the spawned process in order to halt the target process (managed by gdb)
It appears that there is only SIGTERM available in Win32, but clearly if I run gdb from the console and Ctrl+C, it thinks it's receiving a SIGINT. Is there a way I can fake this such that the functionality is available on all platforms?
(I am using the subprocess module, and python 2.5/2.6)
Windows doesn't have the unix signals IPC mechanism.
I would look at sending a CTRL-C to the gdb process.
Related
I have a linux daemon (based on python module python-daemon) that needs to spawn two processes (consider a producer and a consumer) of the Multiprocessing module to handle some concurrent I/O (the producer reads from an input stream and the consumer uploads the data using python requests).
As per the python docs (https://docs.python.org/2/library/multiprocessing.html), daemonic processes are not allowed to start child processes. How can I handle this? Are there any documents or examples for this approach?
Pls. advise.
Context:
I have tried using threading module. But, due to the GIL problem, the consumer rarely gets a chance to execute. I also looked into tornado and gevent. But, that would require rewriting a lot of the code.
I think there is some confusion here. Document says only if you mark the process that has been created from python as daemon then it cannot create sub process. But your python-daemon is a normal linux daemon.
linux daemon - process running in background. (python daemon library creates such process), these can have subprocess
Only a daemon process created from multiprocessing library cannot create sub-process.
I'm developing a python script that runs as a daemon in a linux environment. If and when I need to issue a shutdown/restart operation to the device, I want to do some cleanup and log data to a file to persist it through the shutdown.
I've looked around regarding Linux shutdown and I can't find anything detailing which, if any, signal, is sent to applications at the time of shutdown/restart. I assumed sigterm but my tests (which are not very good tests) seem to disagree with this.
When Linux is shutting down, (and this is slightly dependent on what kind of init scripts you are using) it first sends SIGTERM to all processes to shut them down, and then I believe will try SIGKILL to force them to close if they're not responding to SIGTERM.
Please note, however, that your script may not receive the SIGTERM - init may send this signal to the shell it's running in instead and it could kill python without actually passing the signal on to your script.
Hope this helps!
I've seen the signal module, it seems alright for installing signal handlers and setting up alarms but is sending a signal to another process done via, for example
os.system('kill -s SIGUSR2 8269')
And then is there a simple way to do this if the process is on a different host machine?
os.kill() for local processes, paramiko and the kill command for remote systems.
I'm obtaining a PID, using python, of a CGI script, however, the PID is not valid i.e. can't Taskkill it from CL. I get:
"Process: no process found with pid xxxx" where xxxx is the pid
I thought maybe I have to kill a parent python shell instance, but os.ppid doesn't work in windows.
So then I installed psutil python module and can now get parent PID, but it just shows the parent as the actual WebServer (Abyss), which I don't think I want to kill, since it is the http process that I notice runs constantly and not just a CGI interpreter instance.
Using psutil I CAN get the process status of the actual script, using the pid returned by os.getpid(), and see that it is running. So the pid works for purposes of process information retrieval using psutil. But this gets me no further to obtaining the actual PID I need to kill the script, using EITHER Taskkill on the CL or via kill() from psutil!
What exactly is a cgi shell script from a process perspective, and if it is not a process, why is os.getpid() returning a pid?
Why are you assured that your CGI script are still working when you try to kill it? Web server starts one instance of CGI script for one request and when script finishes it... just finishes.
I have a python script that does some jobs. I use multiprocessing.Pool to have a few workers do some commands for me.
My problem is when I try to terminate the script. When I press Ctrl-C, I would like, that every worker immediately cleans up its experiment (which is some custom code, or actually even a subprocess command, not just releasing locks or memory) and stops.
I know that I can catch Ctrl-C with the signal handler. How can I make all current running workers of a multiprocessing.Pool to terminate, still doing their cleanup command?
Pool.terminate() will not be useful, because the processes will be terminated without cleaning up.
How about trying the atexit standard module?
It allows you to register a function that will be executed upon termination.
Are you working with Unix? If yes, why not catch SIGTERM in the subprocesses? In fact, the documentation of Process.terminate() reads:
Terminate the process. On Unix this is done using the SIGTERM signal
(I have not tested this.)