ps

List, Query, Manipulate System Processes

lifecycle R build status CRAN status CRAN RStudio mirror downloads Coverage status

ps implements an API to query and manipulate system processes. Most of its code is based on the psutil Python package.

Installation

You can install the released version of ps from CRAN with:

install.packages("ps")

Supported platforms

ps currently supports Windows (from Vista), macOS and Linux systems. On unsupported platforms the package can be installed and loaded, but all of its functions fail with an error of class "not_implemented".

Listing all processes

ps_pids() returns all process ids on the system. This can be useful to iterate over all processes.

library(ps)
ps_pids()[1:20]
##  [1]  0  1 51 52 55 56 57 59 62 63 64 65 70 74 76 77 82 83 85 87

ps() returns a data frame (tibble if you have the tibble package available), with data about each process. It contains a handle to each process, in the ps_handle column, you can use these to perform more queries on the processes.

ps()
## # A tibble: 386 x 11
##      pid  ppid name  username status     user  system     rss     vms created             ps_handle
##  * <int> <int> <chr> <chr>    <chr>     <dbl>   <dbl>   <dbl>   <dbl> <dttm>              <I(list)>
##  1 98737     1 quic… gaborcs… runni…   0.0425  0.0200  2.48e7  3.09e9 2018-07-24 09:41:40 <S3: ps_…
##  2 98327     1 mdwo… _spotli… runni…  NA      NA      NA      NA      2018-07-24 09:39:02 <S3: ps_…
##  3 98318  3718 Goog… gaborcs… runni…   0.0650  0.0276  4.62e7  3.36e9 2018-07-24 09:37:30 <S3: ps_…
##  4 96820  3718 Goog… gaborcs… runni…   0.114   0.0618  5.14e7  3.38e9 2018-07-24 09:10:29 <S3: ps_…
##  5 96817  3718 Goog… gaborcs… runni…   0.953   0.163   1.14e8  3.56e9 2018-07-24 09:09:42 <S3: ps_…
##  6 96816  3718 Goog… gaborcs… runni…   1.58    0.265   1.45e8  3.66e9 2018-07-24 09:09:37 <S3: ps_…
##  7 96809  3718 Goog… gaborcs… runni…   0.865   0.158   1.41e8  3.59e9 2018-07-24 09:09:34 <S3: ps_…
##  8 96680  3718 Goog… gaborcs… runni…  12.5     1.86    2.02e8  3.54e9 2018-07-24 08:41:27 <S3: ps_…
##  9 96679  3718 Goog… gaborcs… runni…  26.5     5.92    1.48e8  3.58e9 2018-07-24 08:41:27 <S3: ps_…
## 10 96678  3718 Goog… gaborcs… runni… 171.     16.1     2.72e8  3.70e9 2018-07-24 08:41:26 <S3: ps_…
## # ... with 376 more rows

Process API

This is a short summary of the API. Please see the documentation of the various methods for details, in particular regarding handles to finished processes and pid reuse. See also “Finished and zombie processes” and “pid reuse” below.

ps_handle(pid) creates a process handle for the supplied process id. If pid is omitted, a handle to the calling process is returned:

p <- ps_handle()
p
## <ps::ps_handle> PID=93065, NAME=R, AT=2018-07-23 17:27:55

Query functions

ps_pid(p) returns the pid of the process.

ps_pid(p)
## [1] 93065

ps_create_time() returns the creation time of the process (according to the OS).

ps_create_time(p)
## [1] "2018-07-23 17:27:55 GMT"

The process id and the creation time uniquely identify a process in a system. ps uses them to make sure that it reports information about, and manipulates the correct process.

ps_is_running(p) returns whether p is still running. It handles pid reuse safely.

ps_is_running(p)
## [1] TRUE

ps_ppid(p) returns the pid of the parent of p.

ps_ppid(p)
## [1] 90285

ps_parent(p) returns a process handle to the parent process of p.

ps_parent(p)
## <ps::ps_handle> PID=90285, NAME=zsh, AT=2018-07-23 16:15:32

ps_name(p) returns the name of the program p is running.

ps_name(p)
## [1] "R"

ps_exe(p) returns the full path to the executable the p is running.

ps_exe(p)
## [1] "/Library/Frameworks/R.framework/Versions/3.5/Resources/bin/exec/R"

ps_cmdline(p) returns the command line (executable and arguments) of p.

ps_cmdline(p)
## [1] "/Library/Frameworks/R.framework/Resources/bin/exec/R"

ps_status(p) returns the status of the process. Possible values are OS dependent, but typically there is "running" and "stopped".

ps_status(p)
## [1] "running"

ps_username(p) returns the name of the user the process belongs to.

ps_username(p)
## [1] "gaborcsardi"

ps_uids(p) and ps_gids(p) return the real, effective and saved user ids of the process. They are only implemented on POSIX systems.

if (ps_os_type()[["POSIX"]]) ps_uids(p)
##      real effective     saved 
##       501       501       501
if (ps_os_type()[["POSIX"]]) ps_gids(p)
##      real effective     saved 
##        20        20        20

ps_cwd(p) returns the current working directory of the process.

ps_cwd(p)
## [1] "/Users/gaborcsardi/works/ps"

ps_terminal(p) returns the name of the terminal of the process, if any. For processes without a terminal, and on Windows it returns NA_character_.

ps_terminal(p)
## [1] "/dev/ttys003"

ps_environ(p) returns the environment variables of the process. ps_environ_raw(p) does the same, in a different form. Typically they reflect the environment variables at the start of the process.

ps_environ(p)[c("TERM", "USER", "SHELL", "R_HOME")]
## TERM                          xterm-256color
## USER                          gaborcsardi
## SHELL                         /bin/zsh
## R_HOME                        /Library/Frameworks/R.framework/Resources

ps_num_threads(p) returns the current number of threads of the process.

ps_num_threads(p)
## [1] 4

ps_cpu_times(p) returns the CPU times of the process, similarly to proc.time().

ps_cpu_times(p)
##            user          system    childen_user children_system 
##        8.023153        1.288586              NA              NA

ps_memory_info(p) returns memory usage information. See the manual for details.

ps_memory_info(p)
##        rss        vms    pfaults    pageins 
##  132501504 2719563776     318180       1028

ps_children(p) lists all child processes (potentially recuirsively) of the current process.

ps_children(ps_parent(p))
## [[1]]
## <ps::ps_handle> PID=90291, NAME=zsh, AT=2018-07-23 16:15:32
## 
## [[2]]
## <ps::ps_handle> PID=93065, NAME=R, AT=2018-07-23 17:27:55

ps_num_fds(p) returns the number of open file descriptors (handles on Windows):

ps_num_fds(p)
## [1] 3
f <- file(tmp <- tempfile(), "w")
ps_num_fds(p)
## [1] 4
close(f)
unlink(tmp)

ps_open_files(p) lists all open files:

ps_open_files(p)
## # A tibble: 3 x 2
##      fd path        
##   <int> <chr>       
## 1     0 /dev/ttys003
## 2     1 /dev/ttys003
## 3     2 /dev/ttys003
f <- file(tmp <- tempfile(), "w")
ps_open_files(p)
## # A tibble: 4 x 2
##      fd path                                                                                 
##   <int> <chr>                                                                                
## 1     0 /dev/ttys003                                                                         
## 2     1 /dev/ttys003                                                                         
## 3     2 /dev/ttys003                                                                         
## 4     3 /private/var/folders/59/0gkmw1yj2w7bf2dfc3jznv5w0000gn/T/RtmpxkerNt/file16b892817efc1
close(f)
unlink(tmp)
ps_open_files(p)
## # A tibble: 3 x 2
##      fd path        
##   <int> <chr>       
## 1     0 /dev/ttys003
## 2     1 /dev/ttys003
## 3     2 /dev/ttys003

Process manipulation

ps_suspend(p) suspends (stops) the process. On POSIX it sends a SIGSTOP signal. On Windows it stops all threads.

ps_resume(p) resumes the process. On POSIX it sends a SIGCONT signal. On Windows it resumes all stopped threads.

ps_send_signal(p) sends a signal to the process. It is implemented on POSIX systems only. It makes an effort to work around pid reuse.

ps_terminate(p) send SIGTERM to the process. On POSIX systems only.

ps_kill(p) terminates the process. Sends SIGKILL on POSIX systems, uses TerminateProcess() on Windows. It make an effort to work around pid reuse.

ps_interrupt(p) interrupts a process. It sends a SIGINT signal on POSIX systems, and it can send a CTRL+C or a CTRL+BREAK event on Windows.

Finished and zombie processes

ps handles finished and Zombie processes as much as possible.

The essential ps_pid(), ps_create_time(), ps_is_running() functions and the format() and print() methods work for all processes, including finished and zombie processes. Other functions fail with an error of class "no_such_process" for finished processes.

The ps_ppid(), ps_parent(), ps_children(), ps_name(), ps_status(), ps_username(), ps_uids(), ps_gids(), ps_terminal(), ps_children() and the signal sending functions work properly for zombie processes. Other functions fail with "zombie_process" error.

Pid reuse

ps functions handle pid reuse as well as technically possible.

The query functions never return information about the wrong process, even if the process has finished and its process id was re-assigned.

On Windows, the process manipulation functions never manipulate the wrong process.

On POSIX systems, this is technically impossible, it is not possible to send a signal to a process without creating a race condition. In ps the time window of the race condition is very small, a few microseconds, and the process would need to finish, and the OS would need to reuse its pid within this time window to create problems. This is very unlikely to happen.

Recipes

In the spirit of psutil recipes.

Find process by name

Using ps() and dplyr:

library(dplyr)
find_procs_by_name <- function(name) {
  ps() %>%
    filter(name == !!name)  %>%
    pull(ps_handle)
}

find_procs_by_name("R")
## [[1]]
## <ps::ps_handle> PID=93065, NAME=R, AT=2018-07-23 17:27:55
## 
## [[2]]
## <ps::ps_handle> PID=86811, NAME=R, AT=2018-07-23 13:22:12
## 
## [[3]]
## <ps::ps_handle> PID=79811, NAME=R, AT=2018-07-23 12:15:12

Without creating the full table of processes:

find_procs_by_name <- function(name) {
  procs <- lapply(ps_pids(), function(p) {
    tryCatch({
      h <- ps_handle(p)
      if (ps_name(h) == name) h else NULL },
      no_such_process = function(e) NULL,
      access_denied = function(e) NULL
    )
  })
  procs[!vapply(procs, is.null, logical(1))]
  }

find_procs_by_name("R")
## [[1]]
## <ps::ps_handle> PID=79811, NAME=R, AT=2018-07-23 12:15:12
## 
## [[2]]
## <ps::ps_handle> PID=86811, NAME=R, AT=2018-07-23 13:22:12
## 
## [[3]]
## <ps::ps_handle> PID=93065, NAME=R, AT=2018-07-23 17:27:55

Wait for a process to finish

On POSIX, there is no good way to wait for non-child processes to finish, so we need to write a sleep-wait loop to do it. (On Windows, and BSD systems, including macOS, there are better solutions.)

as_secs <- function(x) as.numeric(x, units = "secs")

wait_for_process <- function(proc, timeout = Inf, sleep = 0.1) {
  sleep <- as_secs(sleep)
  deadline <- Sys.time() + timeout
  while (ps_is_running(proc) && (timeout == Inf || Sys.time() < deadline)) {
    to <- min(as_secs(deadline - Sys.time()), sleep)
    Sys.sleep(to)
  }
  ! ps_is_running(proc)
}

px <- processx::process$new("sleep", "2")
p <- ps_handle(px$get_pid())
wait_for_process(p, 1)
## [1] FALSE
wait_for_process(p)
## [1] TRUE

Wait for several processes to finish

This is similar, but we need to wait on all processes in a loop.

wait_for_processes <- function(procs, timeout = Inf) {
  gone <- list()
  alive <- procs
  deadline <- Sys.time() + timeout

  check_gone <- function(proc, timeout) {
    proc_gone <- wait_for_process(proc, timeout = timeout)
    if (proc_gone) {
      gone <<- c(gone, list(proc))
      alive <<- setdiff(alive, list(proc))
    }
  }

  while (length(alive)) {
    if (timeout <= 0) break
    for (proc in alive) {
      max_timeout <- 1 / length(alive)
      if (timeout != Inf) {
        timeout <- min(as_secs(deadline - Sys.time()), max_timeout)
        if (timeout <= 0) break
        check_gone(proc, timeout)
      } else {
        check_gone(proc, max_timeout)
      }
    }
  }
  list(gone = gone, alive = alive)
}

px1 <- processx::process$new("sleep", "10")
px2 <- processx::process$new("sleep", "10")
px3 <- processx::process$new("sleep", "1")
px4 <- processx::process$new("sleep", "1")

p1 <- ps_handle(px1$get_pid())
p2 <- ps_handle(px2$get_pid())
p3 <- ps_handle(px3$get_pid())
p4 <- ps_handle(px4$get_pid())

wait_for_processes(list(p1, p2, p3, p4), timeout = 2)
## $gone
## $gone[[1]]
## <ps::ps_handle> PID=98990, NAME=???, AT=2018-07-24 09:45:30
## 
## $gone[[2]]
## <ps::ps_handle> PID=98989, NAME=???, AT=2018-07-24 09:45:30
## 
## 
## $alive
## $alive[[1]]
## <ps::ps_handle> PID=98987, NAME=sleep, AT=2018-07-24 09:45:30
## 
## $alive[[2]]
## <ps::ps_handle> PID=98988, NAME=sleep, AT=2018-07-24 09:45:30

Kill process tree

This sends a signal, so it’ll only work on Unix. Use ps_kill() instead of ps_send_signal() on Windows.

kill_proc_tree <- function(pid, sig = signals()$SIGTERM,
                           include_parent = TRUE) {
  if (pid == Sys.getpid() && include_parent) stop("I refuse to kill myself")
  parent <- ps_handle(pid)
  children <- ps_children(parent, recursive = TRUE)
  if (include_parent) children <- c(children, parent)
  for (p in children) ps_send_signal(p, sig)
  wait_for_processes(children, timeout = 0.1)
}

p1 <- processx::process$new("sleep", "10")
p2 <- processx::process$new("sleep", "10")
p3 <- processx::process$new("sleep", "10")
kill_proc_tree(Sys.getpid(), include_parent = FALSE)
## $gone
## $gone[[1]]
## <ps::ps_handle> PID=98987, NAME=???, AT=2018-07-24 09:45:30
## 
## 
## $alive
## $alive[[1]]
## <ps::ps_handle> PID=98988, NAME=???, AT=2018-07-24 09:45:30
## 
## $alive[[2]]
## <ps::ps_handle> PID=98991, NAME=???, AT=2018-07-24 09:45:32
## 
## $alive[[3]]
## <ps::ps_handle> PID=98992, NAME=???, AT=2018-07-24 09:45:32
## 
## $alive[[4]]
## <ps::ps_handle> PID=98993, NAME=???, AT=2018-07-24 09:45:32

Terminate children

Note, that some R IDEs, including RStudio, run a multithreaded R process, and other threads may start processes as well. reap_children() will clean up all these as well, potentially causing the IDE to misbehave or crash.

reap_children <- function(timeout = 3) {
  procs <- ps_children(ps_handle())

  ## SIGTERM
  lapply(procs, ps_terminate)

  ga <- wait_for_processes(procs, timeout = timeout)

  ## SIGKILL to the survivers
  if (length(ga$alive)) lapply(ga$alive, ps_kill)

  ga2 <- wait_for_processes(ga$alive, timeout = timeout)

  ## Some might still survive
  list(gone = c(ga$gone, ga2$gone), alive = ga2$alive)
}

pxs <- replicate(3, processx::process$new("sleep", "3"))
reap_children()
## $gone
## $gone[[1]]
## <ps::ps_handle> PID=98994, NAME=???, AT=2018-07-24 09:45:32
## 
## $gone[[2]]
## <ps::ps_handle> PID=98995, NAME=???, AT=2018-07-24 09:45:32
## 
## $gone[[3]]
## <ps::ps_handle> PID=98996, NAME=???, AT=2018-07-24 09:45:32
## 
## 
## $alive
## list()

Filtering and sorting processes

Process name ending with “sh”:

ps() %>%
  filter(grepl("sh$", name))
## # A tibble: 21 x 11
##      pid  ppid name  username  status     user  system    rss    vms created             ps_handle 
##    <int> <int> <chr> <chr>     <chr>     <dbl>   <dbl>  <dbl>  <dbl> <dttm>              <I(list)> 
##  1 94582 94576 zsh   gaborcsa… running 0.00595 0.00875 8.19e3 2.52e9 2018-07-23 21:06:28 <S3: ps_h…
##  2 94576 94575 zsh   gaborcsa… running 0.243   0.111   1.64e4 2.52e9 2018-07-23 21:06:28 <S3: ps_h…
##  3 93603 93597 zsh   gaborcsa… running 0.00659 0.00973 8.19e3 2.52e9 2018-07-23 17:44:33 <S3: ps_h…
##  4 93597 93596 zsh   gaborcsa… running 0.303   0.133   1.64e4 2.52e9 2018-07-23 17:44:33 <S3: ps_h…
##  5 93482 93476 zsh   gaborcsa… running 0.00524 0.00804 8.19e3 2.52e9 2018-07-23 17:40:47 <S3: ps_h…
##  6 93476 93475 zsh   gaborcsa… running 0.384   0.149   1.64e4 2.52e9 2018-07-23 17:40:46 <S3: ps_h…
##  7 90291 90285 zsh   gaborcsa… running 0.0118  0.0175  8.19e3 2.52e9 2018-07-23 16:15:32 <S3: ps_h…
##  8 90285 90284 zsh   gaborcsa… running 0.256   0.119   1.64e4 2.52e9 2018-07-23 16:15:32 <S3: ps_h…
##  9 90057 90051 zsh   gaborcsa… running 0.0290  0.0514  1.27e6 2.52e9 2018-07-23 16:14:26 <S3: ps_h…
## 10 90051 90050 zsh   gaborcsa… running 0.609   0.281   7.11e6 2.52e9 2018-07-23 16:14:26 <S3: ps_h…
## # ... with 11 more rows

Processes owned by user:

ps() %>%
  filter(username == Sys.info()[["user"]]) %>%
  select(pid, name)
## # A tibble: 258 x 2
##      pid name                
##    <int> <chr>               
##  1 98737 quicklookd          
##  2 98318 Google Chrome Helper
##  3 96820 Google Chrome Helper
##  4 96817 Google Chrome Helper
##  5 96816 Google Chrome Helper
##  6 96809 Google Chrome Helper
##  7 96680 Google Chrome Helper
##  8 96679 Google Chrome Helper
##  9 96678 Google Chrome Helper
## 10 96677 Google Chrome Helper
## # ... with 248 more rows

Processes consuming more than 100MB of memory:

ps() %>%
  filter(rss > 100 * 1024 * 1024)
## # A tibble: 16 x 11
##      pid  ppid name    username  status    user  system    rss    vms created             ps_handle
##    <int> <int> <chr>   <chr>     <chr>    <dbl>   <dbl>  <dbl>  <dbl> <dttm>              <I(list)>
##  1 96817  3718 Google… gaborcsa… runni… 9.53e-1 1.63e-1 1.14e8 3.56e9 2018-07-24 09:09:42 <S3: ps_…
##  2 96816  3718 Google… gaborcsa… runni… 1.58e+0 2.65e-1 1.45e8 3.66e9 2018-07-24 09:09:37 <S3: ps_…
##  3 96809  3718 Google… gaborcsa… runni… 8.65e-1 1.58e-1 1.41e8 3.59e9 2018-07-24 09:09:34 <S3: ps_…
##  4 96680  3718 Google… gaborcsa… runni… 1.25e+1 1.86e+0 2.02e8 3.54e9 2018-07-24 08:41:27 <S3: ps_…
##  5 96679  3718 Google… gaborcsa… runni… 2.65e+1 5.93e+0 1.48e8 3.58e9 2018-07-24 08:41:27 <S3: ps_…
##  6 96678  3718 Google… gaborcsa… runni… 1.71e+2 1.61e+1 2.72e8 3.70e9 2018-07-24 08:41:26 <S3: ps_…
##  7 96674  3718 Google… gaborcsa… runni… 1.04e+1 2.29e+0 1.79e8 3.63e9 2018-07-24 08:41:26 <S3: ps_…
##  8 96673  3718 Google… gaborcsa… runni… 1.06e+2 1.55e+1 1.71e8 3.62e9 2018-07-24 08:41:25 <S3: ps_…
##  9 95883 95882 Virtua… gaborcsa… runni… 2.03e+3 1.32e+3 4.73e9 7.53e9 2018-07-23 22:50:14 <S3: ps_…
## 10 93065 90285 R       gaborcsa… runni… 8.77e+0 1.53e+0 1.33e8 2.75e9 2018-07-23 17:27:55 <S3: ps_…
## 11 90173 90051 Emacs-… gaborcsa… runni… 3.18e+2 5.53e+1 1.99e8 2.89e9 2018-07-23 16:14:37 <S3: ps_…
## 12 92685  3718 Google… gaborcsa… runni… 1.20e+3 1.48e+2 5.32e8 4.89e9 2018-07-22 07:19:55 <S3: ps_…
## 13 35685  3718 Google… gaborcsa… runni… 7.01e+2 7.20e+1 3.67e8 4.15e9 2018-07-19 08:42:23 <S3: ps_…
## 14  3722  3718 Google… gaborcsa… runni… 2.84e+3 1.36e+3 1.44e8 3.40e9 2018-07-17 21:26:21 <S3: ps_…
## 15  3718     1 Google… gaborcsa… runni… 1.14e+4 3.85e+3 4.69e8 4.44e9 2018-07-17 21:26:21 <S3: ps_…
## 16   722     1 iTerm2  gaborcsa… runni… 6.36e+3 1.07e+3 2.24e8 3.59e9 2018-07-17 20:26:27 <S3: ps_…

Top 3 memory consuming processes:

ps() %>%
  top_n(3, rss) %>%
  arrange(desc(rss))
## # A tibble: 3 x 11
##     pid  ppid name     username  status    user system    rss    vms created             ps_handle 
##   <int> <int> <chr>    <chr>     <chr>    <dbl>  <dbl>  <dbl>  <dbl> <dttm>              <I(list)> 
## 1 95883 95882 Virtual… gaborcsa… running  2034.  1320. 4.73e9 7.53e9 2018-07-23 22:50:14 <S3: ps_h…
## 2 92685  3718 Google … gaborcsa… running  1201.   148. 5.32e8 4.89e9 2018-07-22 07:19:55 <S3: ps_h…
## 3  3718     1 Google … gaborcsa… running 11431.  3848. 4.69e8 4.44e9 2018-07-17 21:26:21 <S3: ps_h…

Top 3 processes which consumed the most CPU time:

ps() %>%
  mutate(cpu_time = user + system) %>%
  top_n(3, cpu_time) %>%
  arrange(desc(cpu_time)) %>%
  select(pid, name, cpu_time)
## # A tibble: 3 x 3
##     pid name                       cpu_time
##   <int> <chr>                         <dbl>
## 1 40706 com.docker.hyperkit          31685.
## 2 38474 Google Chrome Helper (GPU)   23568.
## 3 38466 Google Chrome                20589.

Contributions

Please note that this project is released with a Contributor Code of Conduct. By participating in this project you agree to abide by its terms.

License

BSD © RStudio