How can I monitor the thread count of a process on linux?

Question

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?

How about if an application's process only runs for a short time? (Say 2 seconds.) — user2023370, Nov 22 '19 at 17:42

slav0nic · Answer 1 · 2014-03-14T10:01:55.450

194

try

ps huH p <PID_OF_U_PROCESS> | wc -l

or htop

edited Mar 14 '14 at 10:01

answered Nov 07 '08 at 16:56

slav0nic

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I believe you should subtract `1` from it because it prints a line like `USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND` for table header. – ahmet alp balkan Apr 27 '12 at 23:40
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The 'h' hides the header. – thinkmassive Apr 16 '15 at 19:49
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-1 Why pipe the output to `wc` when you could just `ps -o thcount `? See [this answer](https://stackoverflow.com/a/37713259/194894). – Flow Nov 04 '17 at 20:03
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or htop - how con you use it to count number of threads? – andrzejdoro Sep 16 '20 at 13:36
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andrzejdoro, you can enable it in htop setting, just press F2(setup) - Setup Columns - select NLWP in Available Columns and move it into Activated Columns - F10 for save – slav0nic Sep 17 '20 at 10:17

Thejaswi R · Answer 2 · 2018-08-15T13:15:05.637

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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 }'

edited Aug 15 '18 at 13:15

answered Jun 08 '16 at 21:28

Thejaswi R

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Most useful answer here. Especially the `watch` command. However, note that using `thcount` can fail for some (Red Hat...), though `nlwp` worked for me. – Jan 17 '18 at 06:20
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To get the process id of a given process name use `pidof` or `pgrep`. E.g., `ps -o nlwp $(pidof chrome)` or `ps -o nlwp $(pgrep chrome)`. – hmofrad Dec 08 '20 at 18:20

score 72 · Answer 3 · answered Aug 27 '11 at 19:07

72

Each thread in a process creates a directory under /proc/<pid>/task. Count the number of directories, and you have the number of threads.

answered Aug 27 '11 at 19:07

bdonlan

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To add to the above comment. You can use this command to find the number of threads: `find /proc//task -maxdepth 1 -type d -print | wc -l`. Just replace the __ with your process ID that you can get from `top` or using `ps` – Navigatron Oct 14 '16 at 10:15
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@Navigatron: A simple `ls /proc//task | wc` will do nicely. – EvertW Nov 17 '20 at 09:08

score 46 · Answer 4 · edited Nov 03 '15 at 17:26

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cat /proc/<PROCESS_PID>/status | grep Threads

edited Nov 03 '15 at 17:26

Ciro Santilli OurBigBook.com

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answered Apr 21 '15 at 12:51

PbxMan

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Note that you don't need a cat + grep, you can just do a grep... – Alexis Wilke Sep 01 '21 at 04:36

score 22 · Answer 5 · answered Aug 23 '14 at 07:39

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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.

answered Aug 23 '14 at 07:39

This is the sauce for me. I don't want to limit it only to one process. It's easy to add a `-p` to this if necessary, or anything else. This is the minimum you need to see the thread list. – Erick Robertson Apr 06 '16 at 14:45

score 9 · Answer 6 · edited Feb 16 '16 at 02:04

9

$ 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

edited Feb 16 '16 at 02:04

Rao

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answered Feb 16 '16 at 01:03

Avinash Reddy

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score 8 · Answer 7 · answered Sep 12 '20 at 04:13

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.

score 8 · Answer 8 · answered Aug 27 '11 at 18:24

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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.

answered Aug 27 '11 at 18:24

flexo

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Welcome to StackOverflow. Arguably, this should be a comment to the answer by slav0nic. However, as I understand it, when you first join SO, you (still) can't comment on answers until you've gained some reputation, so adding an answer is about all you can do. You are correct; you should not count the header line from `ps` as one of the threads. – Jonathan Leffler Aug 28 '11 at 00:11

jlliagre · Answer 9 · 2014-05-17T20:46:13.503

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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.

edited May 17 '14 at 20:46

answered Jan 20 '14 at 21:31

jlliagre

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score 6 · Answer 10 · answered Nov 06 '08 at 13:36

6

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.

answered Nov 06 '08 at 13:36

rhys keepence

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score 4 · Answer 11 · answered Nov 06 '08 at 13:39

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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.

answered Nov 06 '08 at 13:39

basszero

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score 3 · Answer 12 · answered Feb 10 '21 at 09:47

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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>

answered Feb 10 '21 at 09:47

Serge Mosin

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I wanted to show just amount of threads for all process of a specific user. This answer inspired the following: watch ps -u -o pid,nlwp,args – Puterdo Borato Jul 29 '21 at 12:41

score 2 · Answer 13 · answered Mar 14 '13 at 10:33

2

jvmtop can show the current jvm thread count beside other metrics.

answered Mar 14 '13 at 10:33

MRalwasser

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Saeed Zahedian Abroodi · Answer 14 · 2017-10-23T08:50:44.887

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.

score 1 · Answer 15 · answered Feb 16 '17 at 14:49

1

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

answered Feb 16 '17 at 14:49

Manuel Mndza Bañs

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Andreas Foteas · Answer 16 · 2020-08-26T14:34:45.230

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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.

edited Aug 26 '20 at 14:34

answered Jul 27 '20 at 15:09

Andreas Foteas

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score 0 · Answer 17 · answered Oct 27 '15 at 13:03

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.

score 0 · Answer 18 · answered Oct 31 '22 at 09:40

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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

answered Oct 31 '22 at 09:40

abhishek dubey

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score -1 · Answer 19 · answered Dec 22 '15 at 09:41

-1

VisualVM can show clear states of threads of a given JVM process

answered Dec 22 '15 at 09:41

DiveInto

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self induced thrashing? dang! – Andrew Scott Evans Jun 15 '16 at 16:17

How can I monitor the thread count of a process on linux?

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