Server :: Finding Child Processes Spawned From Screen?
Aug 25, 2010
I have a situation where I have several screen (/usr/bin/screen) sessions running. 2 of the screen sessions (ps1 and ps2) run a script that launched SipP with specific parameters. 1 script starts SipP and has it make 50 calls where the other makes only 20 calls. However The script is configured where we can change how many calls it makes if needed.
So the problem is, due to issues with SipP, we must restart everything every 12 hours (at maximum). So I am trying to work out scripts to stop the SipP processes cleanly. In order to do so I need to figure out which SipP process is spawned by which screen. i.e. which sipp was started by screen session ps1, and which one was started by screen session ps2.
Now I can do ps -ef | grep <number of calls configured> to find out but then I would have to change my stop script every time we reconfigure how many calls are made, and have a separate stop script for each screen session. I would much rather be able to send the screen name as a parameter to the stop script and have it work no matter how many calls SipP is configured to make.Also your standard kill -1 <PID> does not shutdown SipP cleanly. So working out those details is a bit more tricky. Anyone know how I can determine what processes are spawned from a specific screen session?
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Nov 17, 2010
I want to check all the child processes attached to a specific process. Say for a example; my process is a java process. Then I wanna know what are the processes attached to that java process. At the moment I use the command # ps aux|grep java; this gives the details about the currently running java process. So I can kill the whole java process using #kill -9 {pid} ...but there are sub processes attached (I guess child processes) to java process. I wanna view all of them & kill whatever the process I like not the whole thing. I'm using Red hat 5 enterprise edition. and currently a weblogic application server is running on that.
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Sep 6, 2010
I work on Linux for ARM processor for cable modem. There is a tool that I have written (as the job demands) that sends/storms customized UDP packets using raw sockets. I form the packet from scratch so that we have the flexibility to play with different options. This tool is mainly for stress testing routers.
The details are here.
I actually have multiple interfaces created. Each interface will obtain IP addresses using DHCP. This is done in order to make the modem behave as virtual customer premises equipment (vcpe).
When the system comes up, I start those processes that are asked to. Every process that I start will continuously send packets. So process 0 will send packets using interface 0 and so on. Each of these processes that send packets would allow configuration (change in UDP parameters and other options at run time). Thats the reason I decide to have separate processes.
I start these processes using fork and excec from the provisioning processes of the modem.
The problem now is that each process takes up a lot of memory. Starting just 3 such processes, causes the system to crash and reboot.
I have tried the following:- 1-I have always assumed that pushing more code to the Shared Libraries will help. So when I tried moving many functions into shared library and keeping minimum code in the processes, it made no difference to my surprise.
2-I also removed all arrays and made them use the heap. However it made no difference. This maybe because the processes runs continuously and it makes no difference if it is stack or heap?
3-I suspect the process from I where I call the fork is huge and that is the reason for the processes that I make result being huge. I am not sure how else I could go about. say process A is huge -> I start process B by forking and excec. B inherits A's memory area. So now I do this -> A starts C which inturn starts B will also not help as C still inherits A?. I used vfork as an alternative which did not help either. I do wonder why.
reduce the memory used by each independent child processes.
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Oct 14, 2010
the wrong part of the forum but basically im working on a project and getting no where what so ever and i was wondering if i could get your help. Basically i have to create two scripts do:
The parent script which is going to:
o spawn several child processes.
o keep track of the progress of the child processes.
[code]...
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Sep 6, 2010
I work on Linux for ARM processor for cable modem. There is a tool that I have written (as the job demands) that sends/storms customized UDP packets using raw sockets. I form the packet from scratch so that we have the flexibility to play with different options. This tool is mainly for stress testing routers.I actually have multiple interfaces created. Each interface will obtain IP addresses using DHCP. This is done in order to make the modem behave as virtual customer premises equipment (vcpe).
When the system comes up, I start those processes that are asked to. Every process that I start will continuously send packets. So process 0 will send packets using interface 0 and so on. Each of these processes that send packets would allow configuration (change in UDP parameters and other options at run time). Thats the reason I decide to have separate processes. I start these processes using fork and excec from the provisioning processes of the modem. The problem now is that each process takes up a lot of memory. Starting just 3 such processes, causes the system to crash and reboot.
I have tried the following:-
1-I have always assumed that pushing more code to the Shared Libraries will. when I tried moving many functions into shared library and keeping minimum code in the processes, it made no difference to my surprise.
2-I also removed all arrays and made them use the heap. However it made no difference. This maybe because the processes runs continuously and it makes no difference if it is stack or heap?
3-I suspect the process from I where I call the fork is huge and that is the reason for the processes that I make result being huge. I am not sure how else I could go about. say process A is huge -> I start process B by forking and excec. B inherits A's memory area. So now I do this -> A starts C which inturn starts B will also not help as C still inherits A?. I used vfork as an alternative which did not help either. I do wonder why.
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Oct 13, 2010
If a process forks its child and communicate with the child using pipe, do closing the write end of the pipe and terminating the writing process have the same effect?
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May 26, 2010
I'm in the process of writing a program that is a server- it will accept connections and stuff, and spawn a child process for each. However, i've run into a small problem. I do NOT want to bother with keeping track of the processes unless i need to. So, i set SA_NOCLDWAIT (#ifdef) on a SIG_IGN to the SIGCHLD handler through sigaction interface. The standard says that it the kernel will then keep track of reaping zombie processes for me (a HUGE plus). However, upon receiving a SIGINT signal, i want to stop the server from accepting new connections (done), and then wait for there to be no new connections. I was thinking of just putting a loop like so:
Code:
while((wait(NULL) != (pid_t)-1) && errno != ECHILD);
However, I'm not *sure* that this will work, especially with SIGCHLD still ignored. So how can i tell if there are still child processes? I can't find any call like int getnumchld(pid_t proc); (i wish). Plus it would be inefficient to spin on that function anyway. OTOH, i would rather *NOT* have to do the same thing in a loop with a system("ps |...>file"); read(file); etc. either. Is there a way i can portably implement this feature (I was hoping i could run it on linux and the major BSDs, at least).
TO SUM IT UP:
How can i tell if a process has no child processes if i've SIG_IGN'd SA_NOCLDWAIT'd the SIGCHLD? Is there a _reasonably_ portable way to do so? I *don't* want to manually wait for EVERY process. Maybe only those still active at the time of SIGTERM, but that requires keeping track of the number of connections and whether those have terminated...
EDIT: Does anyone know if the above code *would* work, even with SIGCHLD ignored and the kernel cleaning up zombies *for* me? I checked the manpage and it doesn't say much.
EDIT1: Note that all of the processes are in the same process group and session. SO i can find them through this as well. Perhaps even setting the uid/gid and finding all processes run by that group?
EDIT2: i have an idea if the above isn't feasible. If there is no "elegant" way to do it, i could reduce the complexity by sending a SIGUSR1 to the whole process group. Each process would then set a flag telling it to send a SIGUSR1 in reply and send a SIGUSR2 when it is done executing. Then i could keep a count of signals. Maybe that would be *easier*. Or perhaps a count of all child processes and just a termination signal to decrement the counter.
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Sep 3, 2010
I'm looking for a way in Perl to be able to take a list of servers, ssh multiple commands to it and store the results. If I do this process serially, sometimes one server will hang the whole script and if it doesn't, it still takes hours to complete.
I'm thinking what I need to do is make a parent loop that calls out a separate process that passes the server name to the child sub process and then executes all the commands I have defined in its own process. If one server 'hangs', at least that won't stop the script from doing all the other servers in the list.
I'm guessing using the fork() command would serve me best, however, all the online descriptions I have found have been vague at best.
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Jul 20, 2010
Im wondering if there is a simple way to protect environment variables to be changed by child processes?
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Jul 22, 2010
I am facing an issue where the process starts hanging. When I closely look at the logs I come to know that some of the child processes that are forked by the parent process are not finished.
1) Is it possible that the child processes that are not finished occupy the socket memory of the parent process and ultimately a point is reached where no socket memory is available to fork new child processes.
2) What is the standard limit of socket memory in linux?
3) What is the fate of such child processes (as I have mentioned above)?
4) How to debug such cases so that the exact problematic area is identified?
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Feb 15, 2011
well i have just started with shell scripting...how to find all child processes of a parent process given to script as argument.
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Apr 11, 2011
I have written a simple script which has to find required patterns from a bunch of files ( where each file is around 2 GB each,which contain the output of seq 1 10000000000000) on an 8 core machine.I am current forking 6 child processes which run simultaneously on 6 cores of the processor & have to search for the required pattern in 6 different files & inform the parent process when a pattern is found using a PIPE.
The problem is,when a child process is done reading a text file looking for a pattern,it is becoming a zombie process.It exits cleanly when i put a $SIG{CHLD} = "IGNORE"; in the script.Can any one tell me whats going on & how do i improve the communication between child and parent processes?
Code:
#!/bin/perl
use strict;
[code]...
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Aug 22, 2011
All of a sudden, my computer feels sluggish. Mouse moves but windows take ages to open, etc. uptime says the load is 7.69 and raising. What is the fastest way to find out which process(es) are the cause of the load? Now, "top" and similar tools isn't the answer because they either show CPU or memory usage but not both at the same time. What I need is the single command which I might be able to type as it happens - something that will figure out any of: "System is trying to swap 8GB of RAM to disk because process X ..." or "process X seeks all over the disk" or "process X uses 400% CPU"
So what I'm looking for is iostat, htop/atop and similar tools run into one with an output like this:
1235 cp - Disk trashing
87 chrome - Uses 2GB of RAM
137 nfs_bench - Uses 95% of the network bandwidth
I don't want a tool that gives me some numbers which I can analyze but a tool that tells me exactly which process causes the current load. Assume that the user in front of the keyboard barely knows how to write "process" but is quickly overwhelmed when it comes to "resident size", "virtual memory" or "process life cycle".
My argument goes like this: User notices problem. There can be thousands of reasons ... well, almost. User wants to know source of problem. The current solutions give me lots of numbers and I need to know what these numbers mean. What I'm looking for is a meta tool. 99% of the data is irrelevant to the problem. So what the tool should do is look for processes which hog some resource and list only those along with "this process needs a lot of CPU, this produces many IRQs, this process allocates a lot of RAM (and it's still growing)".
This will be a relatively short list. It will be much more simple for an newbie to locate the culprit from this list than from the output of, say, htop which gives me about 5000 numbers but requires me to fold multi-threaded processes myself (I have 50 lines which say VIRT 2750M but only 16GB of RAM - the machine ought to swap itself to death but of course, this is a misinterpretation of the data that can happen quickly).
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Oct 27, 2010
I have a desklet that, occasionally after toying with network stuff, will tell me that large amounts of data are being sent/received. What's a good way to determine what processes are occupying these resources?!
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Dec 16, 2009
I thought 'killall' would work, but I need to provide the "command" to kill. I'm really looking for a command that will kill all processes that have a particular file/directory open. Currently, my script fails on an 'umount' because there are several processes that have this filesystem open. The command 'lsof' is a good tool to determine which processes have a filesystem open, but I don't really want to write a script that parses through the 'lsof' output to capture PSIDs. Is there a linux command that can kill all processes that may have a particular filesystem open?
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May 23, 2011
I have a doubt about signals in C programming. I have done this little program to explain it. It creates a child process with fork and, when the child ends, receives the SIGCHLD signal and wait for its termination.Ok, quite easy, BUT when I execute this code the SIGCHLD signal is received twice, first as an error (returns -1) and the second one to finish the child process.I don't understand the meaning of the first received signal. Why is it generated? Is the code wrong? (if you add the SIGINT and press Ctrl+C during the execution it also receives two signals instead of one)
Code: #include <stdio.h>
#include <unistd.h>
#include <string.h>
[code]....
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Jul 30, 2009
I am troubleshooting something and I got this problem.
If I do "pstree -p"
It shows,
Code:
[code]....
However, it does NOT show up in "ps -elf"
Code:
ps -elf | grep soffi
0 S whho 7734 1 0 80 0 - 36435 - 11:14 pts/2 00:00:03 /usr/lib/openoffice/program/soffice.bin -splash-pipe=5
0 S whho 7833 7759 0 80 0 - 751 - 11:21 pts/3 00:00:00 grep soffi
I was wondering if 7735, 7736, 7737, 7743 were really processes. Then I checked /proc, I could cd to /proc/7735, /proc/7736, etc, but I could not ls them out. I looked at the man page of "pstree", it says,
Code:
Child threads of a process are found under the parent process and are shown with the process name in curly braces, e.g.
icecast2---13*[{icecast2}]
So, what does all this mean? Does it mean that 7735, 7736, 7737, 7743 are just threads but not processes? If so, why could I cd to /proc/<id> but not see them in "ps -elf".
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Nov 22, 2010
I want to spawn a GDB session from bash script and keep it working to interact it from outside. But when I start it in background (with '&' sigil).
Code: gdb -x gdb_script.txt ./a.out < gdb_pipe.fifo &
It executes passed script and terminates by itself (I do not pass any data or signals to it)
Code: Breakpoint 33, main (argc=1, argv=0xbffff0f4) at main.c:53
---Type <return> to continue, or q <return> to quit---53
read_main_config();
(gdb) quit
A debugging session is active.
Inferior 1 [process 5957] will be killed.
Quit anyway? (y or n) [answered Y; input not from terminal] What can I do to make it alive?
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Jul 3, 2009
I have this expect process:
Code:
spawn -noecho telnet my.host.com
expect {
[code]...
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Dec 7, 2009
Consider the following code:
Code:
int main()
{
int i=0;
pid_t pid;
for(i=0;i<2;i++)
[code]....
I get the following output:
Parent: chid_pid=4356 i=0 parent's pid=4355
This is child 4356 i=0
This is child 4357 i=1
[code]....
I can observe instead of two children(as I expect) processes there are three. This is because child process 4356 creates its own child. Why all the messages of the type "This is child X i=Y" are concentrated one under another? How exactly fork works? Is affected by the fact that I have a dual-core processor?
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Nov 19, 2009
Is it possible to have an Expect script spawn an SSH session, log in, then go into interactive mode and give control of the SSH session to a Bash script? Here's a simplified example of the script so far:
Code:
#!/bin/bash
expect -c "
[code]....
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Jun 8, 2010
This is a bit complicated to discribe because I don't know the cause, but this problem has been happening for some time (over a few years and generations of kernals), with different Gnome distributions, including Ubuntu (and family) and Fedora. When using Gnome (and only Gnome), I frequently see the screen dim. At the same time, all processes will be locked up. This may happen for a second or two, or it make require a reboot. The mouse can usually move and the underlying program GUIs are still visible, it's just that one or more of the GUIs will be dimmed. This is usually most noticeable with a browser, but that may just be a coincidence.
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Sep 15, 2010
I am getting "child returned status 1" error when I try to tar some downloaded files. This is what I do:
tar xvzf nagios-2.10.tar.gz (I downloaded this file)
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May 24, 2010
I have a transparent proxy Squid-3.0 on Slackware 12.2. I used cron to restart squid every day at 7:30 AM (just /path.to.squid/squid -k kill && /path.to.squid/squid) Some days ago I saw in /var/log/messages that Squid was killed but haven't started. I started it manually and everything was OK. But today everything repeated. And the log file is interesting. I tried to find about it on http://squid-cache.org/ but al in vain. This is from /var/log/messages :
Code:
May 24 07:30:02 konura squid[17188]: Squid Parent: child process 17199 exited due to signal 9
May 24 07:30:02 konura squid[19038]: Squid Parent: child process 19040 started
May 24 07:30:03 konura squid[19038]: Squid Parent: child process 19040 exited with status 1
May 24 07:30:06 konura squid[19038]: Squid Parent: child process 19045 started
[code]....
I need to say that I haven't edited the config file for a long time, but this problem started to happen. ADDED, Solved: I'm not sure, but maybe I found the decision. I deleted about 400 mb of Sarg logs from /var partition. And now squid runs well. Besides, before deleting old logs, 'crontab -e' and 'pkgtool' didn't work And the system wrote me that it's no space left on device. At the same time, 'df -h' showed me that all partitions had enough free space. Seems strange, but that's it. After deleting old proxy statistics, generated by Sarg (this is about 400 mb) 1)squid runs OK and 2)there are no more that annoying messages about abscence of free space.
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Jun 13, 2011
I have running license server on my server. Right now I would like to write small status script and check if software is running.My software include 3 deamons:
1) daemonA
2) daemonB
3) daemonC
My script should check, if each of this deamon is running. If all deamons are running then script should print short output: "License server is running" if one of this daemons is not running, output should "License server is not running". Is it possible to write small loop to check it ? Let say, loop will take new daemon name from deamons pool and will check if its running. Sometimes I need to check more than three daemons of one Program and I dont know how to write good script for this. Maybe somebody could help me with this loop that in the future I could also use; daemonD, daemonE, daemonF.etc.etc. if all daemons from pool is running then..."Software is running"
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Feb 10, 2010
I have some domains on a VPS server. Typical account memory usage for all domains runs at 50% of available, but I have a problem. One domain is causing me trouble because intermittently traffic will spike on that domain, causing so many requests within 1 min that I exceed my memory allocation for my entire VPS package. Apache is then killed but the virtualization software and Apache must then be restarted.
A sample snippet from tops right before the sever went down would like like this:
All of that memory usage adds up. I would like to "throttle" the number of processes that user/domain can run. I think this would be a quick and easy way to keep the domain from taking down my entire VPS. My understanding is that I could do this with the /etc/security/limits.conf file.
Is that correct?
I have never done this before. Do I want to set a hard or soft limit? I think if I wanted to limit the number of processes for "coldclim" to 15 I would add a line to limits.conf like this:
Code:
Assuming that is correct, can anyone tell me how the website would respond once it reached its limit? Would visitor queries become sluggish, or would the website not come up for them at all?
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Nov 1, 2010
I try to write a script which would kill processes of users who are not logged in. My approach is to find out what users are logged in and then kill processes of all nonsystem users who fail the test of being logged. I use `w` for finding all logged in users, but apparently there are users on the list which `w` gives me who own absolutely no process in the output of `ps aux`. How do I log off those users, since killing their processes wont work (since they own no processes)?
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Feb 15, 2011
I have a problem with the permission of the directories under /proc, they are readable and accessible only by Owner (they have permission 500 instead of the usual 555) As a consequence, the processes are visible only to the Owners or to Root. For exampleif I want to check if there is mysql
I see it only with the user mysql or with root because the directory has permission 500
This problem obstacles the functioning of some applications that should check the existence of some processes managed by other users. At the beginning all was working well. But after a while the problem appeared and I dont know which is the reason of it. how to restore the standard management of permissions of / proc?]
I have a Ubuntu server Maverick 10:10.
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Jan 30, 2011
My University gives us access to a Linux server, named stud1.
Code:
me@stud1:~$ uname -a
Linux stud1.some.univ.ac 2.6.9-89.31.1.ELsmp #1 SMP Mon Oct 4 21:41:59 EDT 2010 x86_64 x86_64 x86_64 GNU/Linux
Apparently I was logged in, and never logged out sometime:
Code:
me@stud1:~$ who
<snip>
me pts/37 Jan 30 13:27 (6.6.66.66)
<snip>
me pts/58 Dec 30 19:13
but when trying to find out why I'm still logged in, I can't find it:
Code:
me@stud1:~$ ps faux |grep me
root 30030 0.0 0.0 51128 4360 ? Ss 13:27 0:00 \_ sshd: me [priv]
me 30033 0.0 0.0 51132 2336 ? S 13:27 0:00 \_ sshd: me@pts/37
[code]....
how can I logout this unused session?
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Dec 2, 2010
I googled upto my capability but cant find answer so asking you In one of my apache 2.0.52 machines, we are using worker MPM model. Even if I use 1 start servers, the # of http processes it starts is 5. No matter what value I pass in StartServers, I dont see more than 5-6 http processes
MaxClients 1
ServerLimit 1
ThreadsPerChild 1
StartServers 1
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