What does the “interruptible sleep” state indicate

pswindow-management

I had Firefox running on a Parted Magic LiveCD, then (possibly) as a result of a key combination I don't recall, it quickly vanished from screen and Task Bar/Window List.

However:

  1. ps ax | grep firefox returns the below (and the unneeded grep firefox line). Both ps and the GUI Task Manager, show firefox with seemingly unchanging RSS, VM-SIZE and 0% CPU usage.

    johndoe      1916 36.6 14.0 923772 504372 tty1    Sl   13:30  12:15 firefox

  2. pstree | grep firefox returns:

    init─┬─2*[ROX-Filer───firefox───25*[{firefox}]]

  3. strace -p 1916 returns, and seemingly stays on this line forever:

    futex(0xac975608), FUTEX_WAIT_PRIVATE, 1, NULL

I understand from an answer to What do the STAT column values in ps mean? that S (in Sl) indicates that the process is in an interruptible sleep state.

Can anyone elaborate as to what the state is, in more detail?

EDIT

I will start a new question, with more specifics on my distro, to address the original 2nd question.

Best Answer

@msw did a good job explaining your 2nd Q, and some of your 1st:

B) Suggest any relatively-easy ways to regain any form of control, to (at the very least) save the tabs I had annoyingly opened in Private Browsing mode?

So I'll try and address your 1st Q a bit more:

A) Elaborate as to what the state is, in more detail?

The state values Sl (That's a lowercase L):

   S    Interruptible sleep (waiting for an event to complete)
   l    is multi-threaded (using CLONE_THREAD, like NPTL pthreads do)

                 lifecycle of process

PROCESS STATE CODES
   R  running or runnable (on run queue)
   D  uninterruptible sleep (usually IO)
   S  interruptible sleep (waiting for an event to complete)
   Z  defunct/zombie, terminated but not reaped by its parent
   T  stopped, either by a job control signal or because
      it is being traced
   [...]

Further details can be seen in the signal man page, man 7 signal, as well as in this tutorial, titled: Linux process states.

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