Linux – How to See Details of All Threads in a Process

command lineprocessshell

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

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How can this be achieved in Linux? Thanks!

Best Answer

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.

Related Solutions

Shell – How to kill a particular thread of a process

Threads are an integral part of the process and cannot be killed outside it. There is the pthread_kill function but it only applies in the context of the thread itself. From the docs at the link:

Note that pthread_kill() only causes the signal to be handled in the context of the given thread; the signal action (termination or stopping) affects the process as a whole.

Linux Process CPU – How to Determine the Processor Running a Process

ps can give you that information if you ask for the psr column (or use the -F flag which includes it).

Ex:

$ ps -F $$
UID        PID  PPID  C    SZ   RSS PSR STIME TTY      STAT   TIME CMD
me        6415  6413  0  5210  2624   2 18:52 pts/0    SN     0:00 -su

Or:

$ ps -o pid,psr,comm -p $$
  PID PSR COMMAND
 6415   0 bash

My shell was running on CPU 2 when I ran the first command, on CPU 0 when I ran the second. Beware that processes can change CPUs very, very quickly so the information you actually see is, essentially, already stale.

Some more info in this Super User question's answers:

Linux: command to know the processor number in which a process is loaded?

Best Answer

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Shell – How to kill a particular thread of a process

Linux Process CPU – How to Determine the Processor Running a Process

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