zombie-process | 易学教程

What does signal(SIGCHLD, SIG_DFL); mean?

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问题 I am not handling SIGCHLD in my code. Still my process is removed immediately after termination. I want it to become zombie process. If I set SIGCHLD to SIGDFT then, will it work? How do I set SIGCHLD to SIGDFT? I want process to become zombie, so I can read the child status in parent after waitpid. 回答1: From your question history you seem to be tying yourself in knots over this. Here is the outline on how this works: The default disposition of SIGCHLD is ignore. In other words, if you do

Golang: Child Processes become Zombies

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问题 I have an application in Go that reroutes the STDIN and STDOUT of binaries and then runs them. In a nutshell I'm doing: - create command object with the binary path (lets call the object command A) - create command object with the binary path (calling it command B) - set the stdout of command B to the stdin of Command A - start command A - start command B I noticed whenever the process for command B exits while command A is running, it becomes a zombie process in the process table. Here's an

Question about zombie processess and threads

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问题 i had these questions in my mind since i was reading some new topics on processes and threads. I would be glad if somebody could help me out. 1) What happens if a thread is marked uncancelable, and then the process is killed inside of the critical section? 2) Do we have a main thread for the program that is known to the operating system? i mean does the operating system give the first thread of the program some beneficial rights or something? 3) When we kill a process and the threads are not

Create zombie process

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问题 I am interested in creating a zombie process. To my understanding, zombie process happens when the parent process exits before the children process. However, I tried to recreate the zombie process using the following code: #include <stdlib.h> #include <sys/types.h> #include <unistd.h> int main () { pid_t child_pid; child_pid = fork (); if (child_pid > 0) { exit(0); } else { sleep(100); exit (0); } return 0; } However, this code exits right after execute which is expected. However, as I do ps

Zombie Processes from iPhone Simulator?

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问题 I've been working on apps for a while now and have just recently started noticing these zombie processes being produced for every launch of the app? I've now closed out Xcode and the simulator but they're just sticking around. Is there some new better way of testing your apps on the simulator that avoids this and/or why might this be occurring? ps aux . . . derek 2696 0.0 0.0 0 0 ?? Z 1:25PM 0:00.00 (Test App) derek 93243 0.0 0.0 0 0 ?? Z 9:00AM 0:00.00 (Test App) derek 89633 0.0 0.0 0 0 ?? Z

Where do Zombie processes go after their parent dies?

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问题 A Zombie process is a process that has completed execution, but still has an entry in the process table (the parent hasn't read its exit code, or in other words, it hasn't been "reaped"). An Orphan process is a process whose parent has finished, though it remains running itself (its parent has "passed away" but it is still "alive"). in this case, init will adopt it and will wait for it. So consider this: int main(int argv, char *argc[]) { pid_t p=fork(); if (p<0) { perror("fork"); } // child

How to stop R from leaving zombie processes behind

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问题 Here is a little reproducible example: library(doMC) library(doParallel) registerDoMC(4) timing <- system.time( fitall <- foreach(i=1:1000, .combine = "c") %dopar% { print(i) }) I start up R and look at the process table: > system("ps -efl") F S UID PID PPID C PRI NI ADDR SZ WCHAN STIME TTY TIME CMD 4 S chbr 1 0 5 80 0 - 21399 wait 10:58 ? 00:00:00 /usr/local/lib/R/bin/exec/R --no-save --no-restore 0 S chbr 9 1 0 80 0 - 1113 wait 10:58 ? 00:00:00 sh -c ps -efl 0 R chbr 10 9 0 80 0 - 4294 - 10

What does signal(SIGCHLD, SIG_DFL); mean?

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I am not handling SIGCHLD in my code. Still my process is removed immediately after termination. I want it to become zombie process. If I set SIGCHLD to SIGDFT then, will it work? How do I set SIGCHLD to SIGDFT? I want process to become zombie, so I can read the child status in parent after waitpid. From your question history you seem to be tying yourself in knots over this. Here is the outline on how this works: The default disposition of SIGCHLD is ignore. In other words, if you do nothing, the signal is ignored but the zombie exists in the process table. This why you can wait on it at any

Apache spawning zombie processes when php is called

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I have a site which has been built in modx and when its hit with load uses up all cpu processing power and top is showing a lot of defunct php zombie processes consuming this. Here's the system specs... PHP 5.2.14 php running as suPHP Mysql 5.1.51 Apache 2.0.63 modx 1.0.4 For testing im using ApacheBench and simulating 500 connections with 100 concurrent connections I've tested this out 2 ways now... Turning off .htaccess and stress testing a simple php page that just echoes 'Hello world'. In top this shows php going defunct and turning into a zombie but they go away pretty quickly Calling a

killing child processes at parent process exit

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I'm very new to c and programming and need some help. In c on linux(cygwin) I am required to remove all child processes at exit. I have looked at the other similar questions but can't get it to work. I've tried- atexit(killzombies); //in parent process void killzombies(void) { printf("works"); kill(0, SIGTERM); printf("works"); if (waitpid(-1, SIGCHLD, WNOHANG) < 0) printf("works"); } for some reason, "works" doesn't even print ever. I press ctrl + c to exit. ALSO I have tried- prctl(PR_SET_PDEATHSIG, SIGHUP); //in child process signal(SIGHUP, killMe); void killMe() { printf("works"); exit(1);