Running nginx alpine image. ps is not installed and do not have permission to install ps using apt-get. I have the pid of process. Is there any way I can find out who the owner of process is ?
In this case, I want to figure out who is running nginx master process.
Use ls to find the process owner in the proc directory
ls -ld /proc/816
If you have stat you can display just the owner with fancy formatting:
stat -c '%U' /proc/775
avahi
Bonus: print your user name without looking at $USER
stat -c '%U' /proc/$$
You can find all the information relative to a process in /proc/YOUR_PROCESS_ID/status where YOUR_PROCESS_IDis the PID of your process.
Therefore, you could get the owner of the process by simply running something like this:
cat /proc/YOUR_PROCESS_ID/status | grep "Uid" | cut -f 2 | id -nu
You can use docker top command to get details about all the processes running inside a docker container
Syntax
docker top <container ID or name>
How about checking from active processes list?
top
If looking for specific process name:
top | grep nginx
I have a problem where my Java application opens too many files. Debugging this issue, I am dependent on using lsof.
However running lsof this way takes too much time (more than one minutt):
lsof |grep "java"
I should be able to run it using the -p option, however it "lies". It shows too few lines.
lsof -p <PID of the java process>
This is my proof :
lsof |grep java | wc -l
1510146
lsof -p 802 | wc -l
4735
The same happens if I use the -u option limiting to username (process owner).
My system is :
Linux 3.16.0-4-amd64 #1 SMP Debian 3.16.39-1+deb8u2 (2017-03-07) x86_64 GNU/Linux
Am I missing something ? Is there an alternative to using lsof ?
lsof is not lying.
The output of the command:
lsof |grep java | wc -l
may contain results of files or processes opened by other programs.
The result you are searching for is the result of the command:
lsof -p <PID> | wc -l
You can increase the limit of opened files for the user running your java application adding this line in /etc/security/limits.conf:
<USER> hard nofile 65536
you can check the current user's limits by typing:
su - <USER>
ulimit -a
lsof without parameter lists all open files, including files which are not using file descriptors – such as current working directories, memory mapped library files, and executable text files.
lsof -p <PID> lists open file descriptors. A file descriptor is a data structure used by a program to get a handle on a file, the most well know being 0,1,2 for standard in, standard out, and standard error.
See: https://www.netadmintools.com/art295.html
Based on my observation, it seems that
lsof | grep <pid> | wc -l
will give duplicate count, because every thread in the specified process will add a line, e.g. if your process have 8 threads, the result will be more than 8x the actual file count.
On the other hand,
lsof -p <PID> | wc -l
produce more exact result, because each file is counted (printed) only once.
Although I have not found official reference for this issue yet.
What is the difference between ps and ps -e command in linux ? ps -e gives a longer list .
From the manual,
By default, ps selects all processes with the same effective user ID
(euid=EUID) as the current user and associated with the same terminal
as the invoker.
For example, if you open a gnome-terminal and give the ps command, it will list all your processes started from that terminal.
ps -e lists all the processes in the system.
When I run the ps command i get a warning saying "Warning: bad syntax, perhaps a bogus '-'? See /usr/share/doc/procps-3.2.7/FAQ"
How do i suppress this warning? Is there some system setting that i must do for this. The command that i fire is :
[root#localhost home]# ps -aux | grep "curl -s -o Test"
Warning: bad syntax, perhaps a bogus '-'? See /usr/share/doc/procps-3.2.7/FAQ
root 4856 0.0 0.0 4044 672 pts/0 S+ 07:20 0:00 grep curl -s -o Test
[root#localhost home]#
Note that I have to fire the exact same command as above. That is why i am looking for some system setting that will suppress the warning.
From the FAQ:
Why does "ps -aux" complain about a bogus '-'?
According to the POSIX and UNIX standards, the above command asks to display
all processes with a TTY (generally the commands users are running) plus all
processes owned by a user named "x". If that user doesn't exist, then ps will
assume you really meant "ps aux". The warning is given to gently break you of a
habit that will cause you trouble if a user named "x" were created.
On my system, where a user x does not exist, I get no warning message. Therefore one can surmise that, on your system, a user named x exists.
If you can remove user x you can probably get the warning to go away. If not, you are stuck with the warning message.
Try:
ps -aux | grep "curl -s -o Test" 2> /dev/null
Or a variant of that.
I would like to monitor the number of threads used by a specific process on Linux.
Is there an easy way to get this information without impacting the performance of the process?
try
ps huH p <PID_OF_U_PROCESS> | wc -l
or htop
To get the number of threads for a given pid:
$ ps -o nlwp <pid>
Where nlwp stands for Number of Light Weight Processes (threads). Thus ps aliases nlwp to thcount, which means that
$ ps -o thcount <pid>
does also work.
If you want to monitor the thread count, simply use watch:
$ watch ps -o thcount <pid>
To get the sum of all threads running in the system:
$ ps -eo nlwp | tail -n +2 | awk '{ num_threads += $1 } END { print num_threads }'
Each thread in a process creates a directory under /proc/<pid>/task. Count the number of directories, and you have the number of threads.
cat /proc/<PROCESS_PID>/status | grep Threads
ps -eLf on the shell shall give you a list of all the threads and processes currently running on the system.
Or, you can run top command then hit 'H' to toggle thread listings.
$ ps H p pid-id
H - Lists all the individual threads in a process
or
$cat /proc/pid-id/status
pid-id is the Process ID
eg.. (Truncated the below output)
root#abc:~# cat /proc/8443/status
Name: abcdd
State: S (sleeping)
Tgid: 8443
VmSwap: 0 kB
Threads: 4
SigQ: 0/256556
SigPnd: 0000000000000000
If you use:
ps uH p <PID_OF_U_PROCESS> | wc -l
You have to subtract 1 to the result, as one of the lines "wc" is counting is the headers of the "ps" command.
My answer is more gui, but still within terminal. Htop may be used with a bit of setup.
Start htop.
Enter setup menu by pressing F2.
From leftmost column choose "Columns"
From rightmost column choose the column to be added to main monitoring output, "NLWP" is what you are looking for.
Press F10.
JStack is quite inexpensive - one option would be to pipe the output through grep to find active threads and then pipe through wc -l.
More graphically is JConsole, which displays the thread count for a given process.
Here is one command that displays the number of threads of a given process :
ps -L -o pid= -p <pid> | wc -l
Unlike the other ps based answers, there is here no need to substract 1 from its output as there is no ps header line thanks to the -o pid=option.
Newer JDK distributions ship with JConsole and VisualVM. Both are fantastic tools for getting the dirty details from a running Java process. If you have to do this programmatically, investigate JMX.
If you're looking for thread count for multiple processes, the other answers won't work well for you, since you won't see the process names or PIDs, which makes them rather useless. Use this instead:
ps -o pid,nlwp,args -p <pid_1> <pid_2> ... <pid_N>
In order to watch the changes live, just add watch:
watch ps -o pid,nlwp,args -p <pid_1> <pid_2> ... <pid_N>
jvmtop can show the current jvm thread count beside other metrics.
The easiest way is using "htop". You can install "htop" (a fancier version of top) which will show you all your cores, process and memory usage.
Press "Shift+H" to show all process or press again to hide it.
Press "F4" key to search your process name.
Installing on Ubuntu or Debian:
sudo apt-get install htop
Installing on Redhat or CentOS:
yum install htop
dnf install htop [On Fedora 22+ releases]
If you want to compile "htop" from source code, you will find it here.
If you are trying to find out the number of threads using cpu for a given pid I would use:
top -bc -H -n2 -p <pid> | awk '{if ($9 != "0.0" && $1 ~ /^[0-9]+$/) print $1 }' | sort -u | wc -l
If you want the number of threads per user in a linux system then you should use:
ps -eLf | grep <USER> | awk '{ num += $6 } END { print num }'
where as <USER> use the desired user name.
If you're interested in those threads which are really active -- as in doing something (not blocked, not timed_waiting, not reporting "thread running" but really waiting for a stream to give data) as opposed to sitting around idle but live -- then you might be interested in jstack-active.
This simple bash script runs jstack then filters out all the threads which by heuristics seem to be idling, showing you stack traces for those threads which are actually consuming CPU cycles.
First get the process ID (pid) by executing below command:
ps -ef | grep (for e.g ps -ef | grep java)
Now replace the pid in below command and execute to get the total thread count of a process.
ps huH p | wc -l
VisualVM can show clear states of threads of a given JVM process