Unpausing paused OS X applications

I had a lot of windows and tabs open in the Safari web browser on my MacBook Pro laptop running OS X 10.10.5 (Yosemite) as well as many other apps open. I've found when I leave many browser tabs open for a prolonged period that eventually they consume almost all of the system's memory. The Activity Monitor application was showing about 15 GB of the system's 16 GB of memory as in use. I closed a couple of tabs, but then opened another one. Then I got the "spinning beachball" and could do nothing further with Safari, so I clicked on the Apple icon at the top, left-hand corner of the screen and chose Force Quit and forced Safari to quit. That reduced the "memory used" value from about 15 GB down to about 5 GB, but I saw that many other applications were listed as "paused" in the Force Quit Applications window and I could no longer use those applications - I just got the multi-colored, spinning beach ball when I clicked on them or tried to access them by cycling through open applications with Command-Tab.

Force Quit Applications - apps paused

The Activity Monitor window showed those applications as "Not Responding".

Activity Monitor - Not
Responding

The Terminal application is not shown as "Not Responding" in the Activity Monitor window, though it is shown as "paused" in Force Quit Applications because I unpaused it prior to taking the Activity Monitor screenshot. To unpause applications, I needed to access a Terminal window to issue "kill -CONT" commands. You can use kill commands to stop errant processes, but you can also use kill -CONT pid commands where pid is the process identifier (PID) of the process you wish to "unpause" to cause a process to resume or "continue" its operation - see Suspending and resuming a process on OS X.

So the first step I took was to configure the MacBook Pro to function as an Secure Shell (SSH) server. I then established an SSH connection to the system from another system. From the Activity Monitor window, I could see the process identifier (PID) for the Terminal application was 304 - if you don't see the PID column in the Activity Monitor application, which is found in the /Applications/Utilities directory, click on View from the program's menu bar, then select Columns and select Process ID, so it has a check mark to the left of it. I checked its status from the shell prompt with ps 304 and then unpaused it with kill -CONT 304, which changed the "STAT" column value from "S" to "U".

$ ps 304
  PID   TT  STAT      TIME COMMAND
  304   ??  S     11:28.38 /Applications/Utilities/Terminal.app/Contents/MacOS/Term
$ kill -CONT 304
$ ps 304
  PID   TT  STAT      TIME COMMAND
  304   ??  U     11:29.44 /Applications/Utilities/Terminal.app/Contents/MacOS/Term
$

Note: you can also find the PID for a process by piping the output of ps aux into the grep command, i.e.:

$ ps aux | grep Terminal | grep -v grep
jasmith1          304   0.0  0.1  2781776  20624   ??  S    17Aug16  11:28.38 /Applications/Utilities/Terminal.app/Contents/MacOS/Terminal -psn_0_40970

The process ID, e.g., 304 in this instance, is displayed after the user name.

Once I resumed the Terminal process with the above command, its status no longer showed "Not Responding" in Activity Monitor, but still showed as "paused" in the Force Quit Applications window even after I closed and reopened the Force Quit Applications window.

I used kill -CONT 1081 to unpause Microsoft Excel, which caused the "Not Responding" that appeared next to the Microsoft Excel process name in the Activity Monitor to disappear. But as with Terminal, it still showed as "paused" in the Force Quit Applications window. I was able to access workbooks I had open in Excel then, though, whereas I had just got the spinning beachball when I tried accessing Excel prior to issuing the kill -CONT 1081 command. I then unpaused other applications using kill -CONT pid commands.

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