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For Windows, I think Process Explorer shows you all the threads under a process.
Is there a similar command line utility for Linux that can show me details about all the threads a particular process is spawning?
I think I should have made myself more clear. I do not want to see the process hierarcy, but a list of all the threads spawned by a particular process
See this screenshot
How can this be achieved in Linux? Thanks!
The classical tool top shows processes by default but can be told to show threads with the H key press or -H command line option. There is also htop, which is similar to top but has scrolling and colors; it shows all threads by default (but this can be turned off). ps also has a few options to show threads, especially H and -L.
There are also GUI tools that can show information about threads, for example qps (a simple GUI wrapper around ps) or conky (a system monitor with lots of configuration options).
For each process, a lot of information is available in /proc/12345 where 12345 is the process ID. Information on each thread is available in /proc/12345/task/67890 where 67890 is the kernel thread ID. This is where ps, top and other tools get their information.
htop does not seem to show me the threads. They mention the H key as a way to swap between showing and hiding threads, but it works as the Help key still...
Aug 10, 2019 at 4:39
h for help, uppercase H to show/hide threads.
Aug 10, 2019 at 7:46
I would like to make it clear that each answer here is providing you with exactly what you have specified, a list of all threads associated with a process, this may not be obvious in htop as it, by default, lists all threads on the system, not just the process but top -H -p <pid> works better for example:
top - 00:03:29 up 3 days, 14:49, 5 users, load average: 0.76, 0.33, 0.18
Tasks: 18 total, 0 running, 18 sleeping, 0 stopped, 0 zombie
Cpu(s): 22.6%us, 5.7%sy, 4.2%ni, 66.2%id, 0.8%wa, 0.5%hi, 0.1%si, 0.0%st
Mem: 2063948k total, 1937744k used, 126204k free, 528256k buffers
Swap: 1052220k total, 11628k used, 1040592k free, 539684k cached
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
30170 daniel 20 0 371m 140m 107m S 10.0 7.0 0:31.37 source:src
30066 daniel -90 0 371m 140m 107m S 2.0 7.0 0:07.87 clementine
30046 daniel 20 0 371m 140m 107m S 0.0 7.0 0:32.05 clementine
30049 daniel 20 0 371m 140m 107m S 0.0 7.0 0:00.03 clementine
30050 daniel 20 0 371m 140m 107m S 0.0 7.0 0:00.31 clementine
30051 daniel 20 0 371m 140m 107m S 0.0 7.0 0:00.00 clementine
30052 daniel 20 0 371m 140m 107m S 0.0 7.0 0:00.00 clementine
30053 daniel 20 0 371m 140m 107m S 0.0 7.0 0:00.00 clementine
30054 daniel 20 0 371m 140m 107m S 0.0 7.0 0:00.03 clementine
30055 daniel 20 0 371m 140m 107m S 0.0 7.0 0:00.00 clementine
30056 daniel 20 0 371m 140m 107m S 0.0 7.0 0:00.00 clementine
30057 daniel 20 0 371m 140m 107m S 0.0 7.0 0:00.04 clementine
30058 daniel 20 0 371m 140m 107m S 0.0 7.0 0:00.00 clementine
30060 daniel 20 0 371m 140m 107m S 0.0 7.0 0:00.16 clementine
30061 daniel 20 0 371m 140m 107m S 0.0 7.0 0:00.00 clementine
30062 daniel 20 0 371m 140m 107m S 0.0 7.0 0:00.00 clementine
30064 daniel 20 0 371m 140m 107m S 0.0 7.0 0:00.00 clementine
30065 daniel 20 0 371m 140m 107m S 0.0 7.0 0:00.00 clementine
As a side note, the thread with -90 is actually a real-time thread.
There's also another option which is true CLI: ps. It depends if you want to look for a process id (pid), for an application name, or more filters.
It does not work on MacOS or BSD, as there the -T parameter has a different meaning and there is no alternative to show threads.
ps with a pidUse ps -T -p <pid>
-T lists all threads-p specifies the process idHere's an example:
$ ps -T -p 30046
PID SPID TTY TIME CMD # this is here for clarity
30046 30046 pts/2 00:00:17 clementine
30046 30049 pts/2 00:00:00 clementine
30046 30050 pts/2 00:00:00 clementine
30046 30051 pts/2 00:00:00 clementine
30046 30052 pts/2 00:00:00 clementine
30046 30053 pts/2 00:00:00 clementine
30046 30054 pts/2 00:00:00 clementine
30046 30055 pts/2 00:00:00 clementine
30046 30056 pts/2 00:00:00 clementine
30046 30057 pts/2 00:00:00 clementine
30046 30058 pts/2 00:00:00 clementine
30046 30060 pts/2 00:00:00 clementine
30046 30061 pts/2 00:00:00 clementine
30046 30062 pts/2 00:00:00 clementine
30046 30064 pts/2 00:00:00 clementine
30046 30065 pts/2 00:00:00 clementine
30046 30066 pts/2 00:00:03 clementine
ps with an application nameUse ps -T -C <application name>
-T lists all threads-C specifies the <application name>Here's an example:
$ ps -e -T -C clementine
PID SPID TTY TIME CMD # this is here for clarity
30046 30046 pts/2 00:00:17 clementine
30046 30049 pts/2 00:00:00 clementine
30046 30050 pts/2 00:00:00 clementine
30046 30051 pts/2 00:00:00 clementine
30046 30052 pts/2 00:00:00 clementine
30046 30053 pts/2 00:00:00 clementine
30046 30054 pts/2 00:00:00 clementine
30046 30055 pts/2 00:00:00 clementine
30046 30056 pts/2 00:00:00 clementine
30046 30057 pts/2 00:00:00 clementine
30046 30058 pts/2 00:00:00 clementine
30046 30060 pts/2 00:00:00 clementine
30046 30061 pts/2 00:00:00 clementine
30046 30062 pts/2 00:00:00 clementine
30046 30064 pts/2 00:00:00 clementine
30046 30065 pts/2 00:00:00 clementine
30046 30066 pts/2 00:00:03 clementine
ps with a filterUse ps -e -T | grep <filter>
-e shows all processes-T lists all threads| pipes the output to the next commandgrep this filters the contents by a <filter> (in this case <application name>)Here's an example:
$ ps -e -T | grep clementine
PID SPID TTY TIME CMD # this is here for clarity
30046 30046 pts/2 00:00:17 clementine
30046 30049 pts/2 00:00:00 clementine
30046 30050 pts/2 00:00:00 clementine
30046 30051 pts/2 00:00:00 clementine
30046 30052 pts/2 00:00:00 clementine
30046 30053 pts/2 00:00:00 clementine
30046 30054 pts/2 00:00:00 clementine
30046 30055 pts/2 00:00:00 clementine
30046 30056 pts/2 00:00:00 clementine
30046 30057 pts/2 00:00:00 clementine
30046 30058 pts/2 00:00:00 clementine
30046 30060 pts/2 00:00:00 clementine
30046 30061 pts/2 00:00:00 clementine
30046 30062 pts/2 00:00:00 clementine
30046 30064 pts/2 00:00:00 clementine
30046 30065 pts/2 00:00:00 clementine
30046 30066 pts/2 00:00:03 clementine
Each of these has the same PID so you know they are in the same process.
sed instead of grep you can preserve the title with trivial code: ps -e -T | sed -n '1p; /clementine/p;'
ps -Tp <pid>? It's quick, simple, and more reliable than grep (which could have false positives).
Jan 10, 2020 at 17:45
htop, a curses version of top, has a display option for showing all the threads for each process in a tree view. Starting htop and pressing F5 will result in:
You may try to use:
/usr/bin/pstree $PID
For example:
# pstree -p `pidof iceweasel`
iceweasel(3630)─┬─{iceweasel}(3662)
├─{iceweasel}(3663)
├─{iceweasel}(3664)
├─{iceweasel}(3665)
├─{iceweasel}(3666)
├─{iceweasel}(3674)
├─{iceweasel}(3675)
├─{iceweasel}(3676)
├─{iceweasel}(3677)
├─{iceweasel}(3681)
├─{iceweasel}(3682)
...
Each thread has its own PID. From the man page:
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}]
The two standard tools to show process informations are ps and top (and htop which is similar/improved).
Notes:
ps -m, ps m, ps H...)Realtime view of all or process, using top -H
top - 16:24:42 up 3:49, 3 users, load average: 0.23, 0.29, 0.31
Threads: 503 total, 2 running, 501 sleeping, 0 stopped, 0 zombie
%Cpu(s): 9.7 us, 1.6 sy, 0.0 ni, 88.5 id, 0.2 wa, 0.0 hi, 0.0 si, 0.0 st
KiB Mem: 3938668 total, 2148708 used, 1789960 free, 133524 buffers
KiB Swap: 3903484 total, 0 used, 3903484 free. 822904 cached Mem
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
1054 root 20 0 258664 3524 2692 S 0.0 0.1 0:00.00 rsyslogd
1086 root 20 0 258664 3524 2692 S 0.0 0.1 0:00.03 in:imuxsock
1087 root 20 0 258664 3524 2692 S 0.0 0.1 0:00.00 in:imklog
1090 root 20 0 258664 3524 2692 S 0.0 0.1 0:00.05 rs:main Q:Reg
2452 fpiat 20 0 25292 7520 3580 S 0.0 0.2 0:00.69 bash
2495 fpiat 20 0 25088 6988 3256 S 0.0 0.2 0:00.05 bash
Instant view of all process and threads, using ps -eLf
$ ps -eLf
UID PID PPID LWP C NLWP STIME TTY TIME CMD
root 1054 1 1054 0 4 12:34 ? 00:00:00 /usr/sbin/rsyslogd -n
root 1054 1 1086 0 4 12:34 ? 00:00:00 /usr/sbin/rsyslogd -n
root 1054 1 1087 0 4 12:34 ? 00:00:00 /usr/sbin/rsyslogd -n
root 1054 1 1090 0 4 12:34 ? 00:00:00 /usr/sbin/rsyslogd -n
franklin 2452 2448 2452 0 1 12:35 pts/0 00:00:00 /bin/bash
franklin 2495 2448 2495 0 1 12:36 pts/1 00:00:00 /bin/bash
Threads information of a process, using ps -T
ps -T -C rsyslogd
PID SPID TTY TIME CMD
1054 1054 ? 00:00:00 rsyslogd
1054 1086 ? 00:00:00 in:imuxsock
1054 1087 ? 00:00:00 in:imklog
1054 1090 ? 00:00:00 rs:main Q:Reg
(note: use either option -C command, or -p PID to select the process)
Details threads information of a process, using custom ps
$ ps -L -o pid,lwp,pri,nice,start,stat,bsdtime,cmd,comm -C rsyslogd
PID LWP PRI NI STARTED STAT TIME CMD COMMAND
1054 1054 19 0 12:34:53 Ssl 0:00 /usr/sbin/rsyslogd -n rsyslogd
1054 1086 19 0 12:34:53 Ssl 0:00 /usr/sbin/rsyslogd -n in:imuxsock
1054 1087 19 0 12:34:53 Ssl 0:00 /usr/sbin/rsyslogd -n in:imklog
1054 1090 19 0 12:34:53 Ssl 0:00 /usr/sbin/rsyslogd -n rs:main Q:Reg
You can try top -H -p <pid>.
But please note on some Unix flavors '-H' option is not available in top command.
-H; Linux uses GNU tools (including ps) and UNIX does not. (This is, of course, a generalization...)
ps -H le <pid>
This shall display threads as processes. Also remember that all threads of a multi-threaded must have same PID. Linux does this by making thread groups. First thread is the leader of the group and its PID will be tgid(thread groupID) of the thread group.
You can find out actual PID and status of threads by using /proc file system. Another way to achieve this is to check the PID by using ps, then run following command:
cat /proc/pid/status
Then check further pids/tgid of threads and run following command:
cat /proc/pid/task/threadid/status
top -H -p <process_id>
This will list you the threads, associated with your process (i.e. process_id) [Used on Ubuntu. There is possibility that the option -H is not available on some of the linux flavors]
ps huH -p pid | wc -l
Above command shows the number of running thread for specific process pid if for java process
I was looking for the same, and was able to come up with the following bash script,
This is still work in progress, I will update this as I improve the script.
I am no unix expert,I am sure some expert can write it in 2 lines, with a better quality, but my intention is to provide a working solution for others.
update with filter and process information
#!/bin/bash
ps -ef --no-headers | while read line; do # for each process read the info (without headers)
IFS=' ' read -r -a array <<< "$line" # split info into array
psResultStr="ps -p ${array[1]} -lfT | wc -c" # count how many threads per PID
numThreads=$(eval $psResultStr) # trying to convert it to number so i can filter later
if [ "$numThreads" -gt "1000" ] #only show process with 1K or more
then
printf "Number of threads for PID:${array[1]} Has $numThreads Threads. Process info: "
for ((i = 7; i < ${#array[@]}; ++i)); do #Process info starts at idx 7
position=$(( $i + 1 )) # bash arrays are 0-indexed
lineText=$(echo ${array[$i]}|tr -d '\n') # remove any new lines
printf "%s" "$lineText" #output line item
done
printf "\n\n"
fi
done
