Please help.
So, I'm given a task to monitor a particular process in CentOS.
There are certain requirements.
Can't monitor using PID, because once process is killed or dead, solution is of no use.
It'll be great if I could know how much is the consumption of each thread of a process.
I've researched enough but with no success.
Thanks in advance.
I am uncertain what exactly you are trying to achieve, but this is how I would proceed:
Suggested Approaches
Multiple Process IDs per process name
top -H -p $(pgrep <process_name> | paste -s -d, -)
Single Process ID per process name
top -H -p $(pgrep <process_name>)
Further reading
Reuse command output
Thread Monitoring with top
Turn stdout into comma-separated string
Suggestion
Maybe think about implementing a solution like Prometheus with Node Exporter or Zabbix or Nagios.
Related
for my Computing Controlled Assessment I am looking into some of the basic commands for the Linux OS Debian. For the final question I have to write a short essay on using the top command along with ps and kill to investigate misbehaving system. The question asks to use help from PC specialists (or just any experienced Debian users). So if anyone could give any information on how a specialist could use these commands and anything helpful in general on these commands. Remember I'm here for information and not an answer. Thanks
top is used for displaying a list of processes, and by default, is sorted by the amount of CPU usage it's using - so in your case, it's a handy tool to see if a specific process is taking up most of the CPU usage and causing the system to run slower. It also displays the process ID (PID) as well as the user running it. Think of it like the Linux equivalent of Task Manager in Windows.
ps is similar to top, but instead of constantly refreshing, it spews out all of the current processes running on the server, as well as the PID (important). Usually this is used as ps aux, or to be more specfic you could use this with grep to search for a specific process, e.g. ps aux | grep httpd to display the current Apache processes running.
kill is used to kill process running on the system, so if you had a script on the system taking up most of the resources and you want to forcefully kill the process, you'd use kill. You can also use the killall command to kill all processes with a matching string, e.g. killall httpd.
The steps I'd take to investigate a misbehaving system would be to:
1) Use top or ps to locate the process taking up the most resources, and remember the process ID.
2) If I wanted to kill the process, I'd use: kill <process ID>.
If you need anything else clarifying or explaining - feel free to comment!
EDIT: https://serverfault.com/ - This may be the best place to post future questions like this.
Best way to learn about this commands is to read man (manual) pages. To discover information about top just type:
$ man top
in command line and enjoy. Similarly you can display man pages for most unit command line tools using:
$ man <command>
on linux can I show a process's detail including what command/script started it, etc?
top is show all processes and I wish to get more information on a process using its id
ps -p <pid> -lF
...will give you information about the process like which command started it, time it was started, its state, parent pid, size etc.
If you can tell in more detail as what all information you want to know about process from pid, then we can help you better.
You can find lots of information in /proc/{PID} directories.
I also want to kill processes which are not running on my kernel, as my system is getting slow. Kindly assist. Using Ubuntu
You can get the total number of running processes with
$ ps aux | wc -l
As for killing processes, you need to be careful with that. However, using top or ps and providing the needed options (see the man pages) you can list processes run by specific users/belonging to specific groups.
If your system is slow, focus on the top memory/cpu consumers and to do that use
$ top
to see which processes are the slowest.
You can then type k (for kill) and then the process you want to kill. Use 15 for a soft-kill and 9 for a hard-kill if the softkill doesn't work.
You can type q to quit.
I have a LINUX server running a process with a large memory footprint (some sort of a database engine). The memory allocated by this process is so large that part of it needs to be swapped (paged) out.
What I would like to do is to lock the memory pages of all the other processes (or a subset of the running processes) in memory, so that only the pages of the database process get swapped out. For example I would like to make sure that i can continue to connect remotely and monitor the machine without having the processes impacted by swapping. I.e. I want sshd, X, top, vmstat, etc to have all pages memory resident.
On linux there are the mlock(), mlockall() system calls that seem to offer the right knob to do the pinning. Unfortunately, it seems to me that I need to make an explicit call inside every process and cannot invoke mlock() from a different process or from the parent (mlock() is not inherited after fork() or evecve()).
Any help is greatly appreciated. Virtual pizza & beer offered :-).
It has been a while since I've done this so I may have missed a few steps.
Make a GDB command file that contains something like this:
call mlockall(3)
detach
Then on the command line, find the PID of the process you want to mlock. Type:
gdb --pid [PID] --batch -x [command file]
If you get fancy with pgrep that could be:
gdb --pid $(pgrep sshd) --batch -x [command file]
Actually locking the pages of most of the stuff on your system seems a bit crude/drastic, not to mention being such an abuse of the mechanism it seems bound to cause some other unanticipated problems.
Ideally, what you probably actually want is to control the "swappiness" of groups of processes so the database is first in line to be swapped while essential system admin tools are the last, and there is a way of doing this.
While searching for mlockall information I ran across this tool. You may be able to find it for your distribution. I only found the man page.
http://linux.die.net/man/8/memlockd
Nowadays, the easy and right way to tackle the problem is cgroup.
Just restrict memory usage of database process:
1. create a memory cgroup
sudo cgcreate -g memory:$test_db -t $User:$User -a $User:$User
2. limit the group's RAM usage to 1G.
echo 1000M > /sys/fs/cgroup/memory/$test_db/memory.limit_in_bytes
or
echo 1000M > /sys/fs/cgroup/memory/$test_db/memory.soft_limit_in_bytes
3. run the database program in the $test_db cgroup
cgexec -g memory:$test_db $db_program_name
I want to use the /proc to find the resource usage of a particular process every second. The resources include cputime, disk usage and network usage. I looked at /proc/pid/stat , but I am not sure whether I am getting the required details. I want all 3 resource usage and I want to monitor them every second.
Some newer kernels have /proc/<pid_of_process>/io file. This is where IO stats are.
It is not documented in man proc, but you can try to figure out the numbers yourself.
Hope it helps.
Alex.
getrusage() accomplishes cpu, memory and disk etc.
man 2 getrusage
I don't know about network.
checkout glances.
It's got cpu disk and network all on one screen. It's not per process but it's better than looking at 3 separate tools.
Don't think there is a way to get the disk and network information on a per process basis.
The best you can have is the global disk and network, and the per process CPU time.
All documented in man proc
netstat -an
Shows all connections to the server including the source and destination ips and ports if you have proper permissions.
ac
Prints statistics about users' connect time
The best way to approach problems like this is to look up the source code of tools that perform similar monitoring and reporting.
Although there is no guarantee that they are using /proc directly, they will lead you to an efficient way to tackle the problem.
For your case, top(1), iotop(8) and nethogs(8) come to mind.
You can use SAR
-x report statistics for a given process.
See this for more details:
http://www.linuxcommand.org/man_pages/sar1.html
Example:
sar -u -r -b 1 -X PID | grep -v Average | grep -v Linux
You can use top
SYNOPSIS
top -hv|-bcHiOSs -d delay -n limit -u|U user -p PID -o champ -w [columns]
This is a screen capture of top in a terminal