signals

问题 In my Django app, I need to start running a few periodic background jobs when a user logs in and stop running them when the user logs out, so I am looking for an elegant way to get notified of a user login/logout query user login status From my perspective, the ideal solution would be a signal sent by each django.contrib.auth.views.login and ... views.logout a method django.contrib.auth.models.User.is_logged_in() , analogous to ... User.is_active() or ... User.is_authenticated() Django 1.1.1

问题 In a comment on this answer of another question, the commenter says: don’t use kill -9 unless absolutely necessary! SIGKILL can’t be trapped so the killed program can’t run any shutdown routines to e.g. erase temporary files. First try HUP (1), then INT (2), then QUIT (3) I agree in principle about SIGKILL , but the rest is news to me. Given that the default signal sent by kill is SIGTERM , I would expect it is the most-commonly expected signal for graceful shutdown of an arbitrary process.

问题 What is the best way to capture a kill signal in java without using JNI. I did discover the sun.misc.Signal and the sun.misc.SignalHandler and the warning of the possibility of being removed in the future releases. Would using JNI to call a c lib be the only option i have? 回答1: The way to handle this would be to register a shutdown hook. If you use ( SIGINT ) kill -2 will cause the program to gracefully exit and run the shutdown hooks. Registers a new virtual-machine shutdown hook. The Java

问题 I recently ran into an issue with Command Prompt on Windows where QuickEdit mode was enabled and clicking the window was selecting text and hanging a running program. This is, apparently, known behaviour—I found a few questions related to it: Command Line Windows Hanging in RDP Windows Windows Console Application Getting Stuck How to disable QuickEdit Mode for individual scripts How is the application "paused"/"suspended"? Is the process similar to the SIGSTOP signal on *nix? (I am also

问题 I read somewhere that we should lock the mutex before calling pthread_cond_signal and unlock the mutext after calling it: The pthread_cond_signal() routine is used to signal (or wake up) another thread which is waiting on the condition variable. It should be called after mutex is locked, and must unlock mutex in order for pthread_cond_wait() routine to complete. My question is: isn't it OK to call pthread_cond_signal or pthread_cond_broadcast methods without locking the mutex? 回答1: If you do

问题 I read somewhere that we should lock the mutex before calling pthread_cond_signal and unlock the mutext after calling it: The pthread_cond_signal() routine is used to signal (or wake up) another thread which is waiting on the condition variable. It should be called after mutex is locked, and must unlock mutex in order for pthread_cond_wait() routine to complete. My question is: isn't it OK to call pthread_cond_signal or pthread_cond_broadcast methods without locking the mutex? 回答1: If you do

问题 I have a PCIe device that will send a hardware interrupt when a data buffer is ready to be read. I believe the best approach for this is to use signals but I'm not entirely sure how. What I believe I need to do is: Save the PID of the user space application so the driver knows where to send the signal In the interrupt handler of the PCIe device driver, send a signal to the user space application In the User space application implement a signal handler function for processing the signal I'm

问题 In the same way that the question Sending “ENTER” key through serial port how can i send the "ARROW key" through the serial port? Most particuly the UP arrow key. 回答1: Cursor keys are a relatively new feature of keyboards. They didn't yet exist at the time the ASCII codes were chosen. Which was largely based on the capabilities of teletypes that were used at that time. Like the widely used ASR-33, its keyboard layout looked like this: No cursor keys. Note how line-feed was a separate key back

问题 In my bash script, I'm running an external command that's stored in $cmd variable. (It could be anything, even some simple bash oneliner.) If ctrl + C is pressed while running the script, I want it to kill the currently running $cmd but it should still continue running the main script. However, I would like to preserve the option to kill the main script with ctrl + C when the main script is running. #!/bin/bash cmd='read -p "Ooook?" something; echo $something; sleep 4 ' while true; do echo

问题 I have a multi-threaded program and want to catch SIGINT. I tried using the signal interface but it appears to stop doing anything when the program uses threading . What is the correct signal API for multi-threaded python programs? import signal import sys import threading import os # register my Ctrl-C handler def signal_handler(signal, frame): print('Signal.') os._exit(0) signal.signal(signal.SIGINT, signal_handler) # stop the main thread lock = threading.Lock() with lock: threading