How do I do "ps" command on a thread?

Question

The ps command can be done in terminal to view information about a process. For example,

#list processes
ps aux
#with executable paths
ps -ef
#path for a specific process
ps -p [pid]

However, if a process is large, it may be necessary to isolate what individual threads are doing. For example, kernel_task. The command sudo dtruss -ap [pid] is not optimal because it requires turning off system resource protection. Is there a way to find ps information about threads without turning off system resource protection?

Thanks

Answer 1

The "-T" option for the ps command enables thread views.

# ps -T -p <pid>

For example, to list the threads for the following java process:

# ps -ef | grep 97947
deploy   97947 97942  1 00:51 ?       00:13:51 java

Alternatively, you can use top which can show a real-time view of individual threads. To enable thread views in the top output, invoke top with "-H" option. This will list all Linux threads. You can also toggle on or off thread view mode while top is running, by pressing 'H' key.

top - 14:43:25 up 6 days,  5:40,  2 users,  load average: 0.87, 0.33, 0.22
Threads: 684 total,   1 running, 683 sleeping,   0 stopped,   0 zombie
%Cpu(s):  6.3 us,  4.0 sy,  0.0 ni, 89.6 id,  0.1 wa,  0.0 hi,  0.0 si,  0.0 st
KiB Mem :  7910136 total,   384812 free,  1603096 used,  5922228 buff/cache
KiB Swap:  8388604 total,  8239100 free,   149504 used.  5514264 avail Mem

Note how in the example above the number of threads on the system is listed.