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ps

List, Query, Manipulate System Processes

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:

If you need the development version, install it with

pak::pak("r-lib/ps")
library(ps)
library(pillar) # nicer printing of data frames

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.

ps_pids()[1:20]
##  [1]    0    1 1125 1127 1129 1130 1133 1136 1138 1139 1144 1149 1153 1155 1156 1161 1164 1165 1166
## [20] 1167

ps() returns a data frame, 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 data frame: 477 × 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 81068     1 mdwo… gaborcs… runni…  0.0377  0.0143  2.61e7  4.20e11 2024-09-01 09:39:46 <ps_handl>
##  2 81067     1 mdwo… gaborcs… runni…  0.0423  0.0133  2.19e7  4.20e11 2024-09-01 09:39:46 <ps_handl>
##  3 80413     1 mdwo… gaborcs… runni…  0.0717  0.0220  2.84e7  4.20e11 2024-09-01 09:39:27 <ps_handl>
##  4 80412     1 mdwo… gaborcs… runni…  0.0749  0.0241  3.00e7  4.20e11 2024-09-01 09:39:27 <ps_handl>
##  5 80366     1 mdwo… gaborcs… runni…  0.287   0.0797  3.00e7  4.20e11 2024-09-01 09:37:07 <ps_handl>
##  6 80360 69319 Goog… gaborcs… runni…  0.0462  0.0191  9.14e7  1.66e12 2024-09-01 09:37:05 <ps_handl>
##  7 80264     1 coun… root     runni… NA      NA      NA      NA       2024-09-01 09:36:10 <ps_handl>
##  8 80261     1 mdwo… gaborcs… runni…  0.300   0.0755  3.00e7  4.20e11 2024-09-01 09:35:55 <ps_handl>
##  9 78900 69319 Goog… gaborcs… runni…  2.26    0.429   1.76e8  1.66e12 2024-09-01 09:26:07 <ps_handl>
## 10 78888 69319 Goog… gaborcs… runni…  5.68    0.595   2.38e8  1.66e12 2024-09-01 09:25:57 <ps_handl>
## # ℹ 467 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=56773, NAME=R, AT=2024-08-31 14:11:26.708347

Query functions

ps_pid(p) returns the pid of the process.

## [1] 56773

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

## [1] "2024-08-31 14:11:26 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.

## [1] TRUE

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

## [1] 55975

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

## <ps::ps_handle> PID=55975, NAME=zsh, AT=2024-08-29 15:04:35.020175

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

## [1] "R"

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

## [1] "/Library/Frameworks/R.framework/Versions/4.4-arm64/Resources/bin/exec/R"

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

## [1] "/Library/Frameworks/R.framework/Versions/4.4-arm64/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".

## [1] "running"

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

## [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.

## [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_.

## [1] "/dev/ttys015"

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/Versions/4.4-arm64/Resources

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

## [1] 3

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

##            user          system   children_user children_system
##        33.87137        15.05281              NA              NA

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

##          rss          vms      pfaults      pageins
##    255983616 423297335296      2173700          742

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

## [[1]]
## <ps::ps_handle> PID=56773, NAME=R, AT=2024-08-31 14:11:26.708347
##
## [[2]]
## <ps::ps_handle> PID=57966, NAME=zsh, AT=2024-08-29 15:04:37.802087

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

## [1] 49
f <- file(tmp <- tempfile(), "w")
ps_num_fds(p)
## [1] 50
close(f)
unlink(tmp)

ps_open_files(p) lists all open files:

## # A data frame: 3 × 2
##       fd path
##    <int> <chr>
##  1     0 /dev/ttys015
##  2     1 /dev/ttys015
##  3     2 /dev/ttys015
f <- file(tmp <- tempfile(), "w")
ps_open_files(p)
## # A data frame: 4 × 2
##       fd path
##    <int> <chr>
##  1     0 /dev/ttys015
##  2     1 /dev/ttys015
##  3     2 /dev/ttys015
##  4    45 /private/var/folders/ph/fpcmzfd16rgbbk8mxvy9m2_h0000gn/T/RtmpFPtZXU/fileddc51cac4863
## # A data frame: 3 × 2
##       fd path
##    <int> <chr>
##  1     0 /dev/ttys015
##  2     1 /dev/ttys015
##  3     2 /dev/ttys015

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=56773, NAME=R, AT=2024-08-31 14:11:26.708347

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=56773, NAME=R, AT=2024-08-31 14:11:26.708347

Wait for a process to finish

ps_wait(), from ps 1.8.0, implements a new way, efficient for waiting on a list of processes, so this is now very easy:

px <- processx::process$new("sleep", "2")
p <- px$as_ps_handle()
ps_wait(p, 1000)
## [1] FALSE
## [1] TRUE

Wait for several processes to finish

Again, this is much simpler with ps_wait(), added in ps 1.8.0.

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 <- px1$as_ps_handle()
p2 <- px2$as_ps_handle()
p3 <- px3$as_ps_handle()
p4 <- px4$as_ps_handle()

ps_wait(list(p1, p2, p3, p4), timeout = 2000)
## [1] FALSE FALSE  TRUE  TRUE

Kill process tree

From ps 1.8.0, ps_kill() will first send SIGTERM signals on Unix, and SIGKILL after a grace period, if needed.

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.

kill_proc_tree <- function(pid, 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, list(parent))
  ps_kill(children, ...)
}

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)
## [1] "terminated" "terminated" "terminated" "terminated" "terminated"

Filtering and sorting processes

Process name ending with “sh”:

ps() %>%
  filter(grepl("sh$", name))
## # A data frame: 38 × 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 67374     1 Report… gaborcs… runni… 0.00899 0.0148  5.47e6 4.20e11 2024-09-01 03:02:35 <ps_handl>
##  2 44801 44603 zsh     gaborcs… runni… 0.00261 0.00945 7.86e5 4.21e11 2024-08-31 09:42:36 <ps_handl>
##  3 44603 44602 zsh     gaborcs… runni… 0.155   0.0547  9.99e5 4.21e11 2024-08-31 09:42:35 <ps_handl>
##  4 24830 24631 zsh     gaborcs… runni… 0.00736 0.0332  7.86e5 4.21e11 2024-08-30 22:11:24 <ps_handl>
##  5 24631 24630 zsh     gaborcs… runni… 0.333   0.134   9.67e5 4.21e11 2024-08-30 22:11:24 <ps_handl>
##  6 58680 55972 zsh     gaborcs… runni… 0.168   0.651   9.34e5 4.21e11 2024-08-29 15:04:39 <ps_handl>
##  7 58570 55971 zsh     gaborcs… runni… 0.0186  0.0693  2.38e6 4.21e11 2024-08-29 15:04:39 <ps_handl>
##  8 58509 55974 zsh     gaborcs… runni… 0.00364 0.0117  7.54e5 4.21e11 2024-08-29 15:04:38 <ps_handl>
##  9 58474 55964 zsh     gaborcs… runni… 0.00367 0.00942 7.54e5 4.21e11 2024-08-29 15:04:38 <ps_handl>
## 10 58437 55966 zsh     gaborcs… runni… 0.00341 0.00986 7.54e5 4.21e11 2024-08-29 15:04:38 <ps_handl>
## # ℹ 28 more rows

Processes owned by user:

ps() %>%
  filter(username == Sys.info()[["user"]]) %>%
  select(pid, name)
## # A data frame: 286 × 2
##      pid name
##    <int> <chr>
##  1 81199 Google Chrome Helper (Renderer)
##  2 81198 Google Chrome Helper (Renderer)
##  3 81197 Google Chrome Helper (Renderer)
##  4 81068 mdworker_shared
##  5 81067 mdworker_shared
##  6 80413 mdworker_shared
##  7 80412 mdworker_shared
##  8 80366 mdworker_shared
##  9 80360 Google Chrome Helper (Renderer)
## 10 80261 mdworker_shared
## # ℹ 276 more rows

Processes consuming more than 100MB of memory:

ps() %>%
  filter(rss > 100 * 1024 * 1024)
## # A data frame: 29 × 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 81199 69319 Google… gaborcs… runni…  0.0412  0.0162 1.07e8 1.66e12 2024-09-01 09:39:54 <ps_handl>
##  2 81198 69319 Google… gaborcs… runni…  0.0704  0.0242 1.22e8 1.66e12 2024-09-01 09:39:53 <ps_handl>
##  3 81197 69319 Google… gaborcs… runni…  1.23    0.565  3.12e8 1.66e12 2024-09-01 09:39:53 <ps_handl>
##  4 78900 69319 Google… gaborcs… runni…  2.27    0.430  1.76e8 1.66e12 2024-09-01 09:26:07 <ps_handl>
##  5 78888 69319 Google… gaborcs… runni…  5.68    0.596  2.38e8 1.66e12 2024-09-01 09:25:57 <ps_handl>
##  6 76222 69319 Google… gaborcs… runni… 34.6     2.86   2.22e8 1.66e12 2024-09-01 09:17:46 <ps_handl>
##  7 74007 69319 Google… gaborcs… runni…  6.59    1.08   1.46e8 1.66e12 2024-09-01 08:37:02 <ps_handl>
##  8 73963 69319 Google… gaborcs… runni…  7.16    0.987  1.86e8 1.66e12 2024-09-01 08:34:37 <ps_handl>
##  9 73601 69319 Google… gaborcs… runni… 98.1    19.2    1.94e8 1.66e12 2024-09-01 07:54:27 <ps_handl>
## 10 69386 69319 Google… gaborcs… runni…  1.38    0.244  1.09e8 1.66e12 2024-09-01 07:06:19 <ps_handl>
## # ℹ 19 more rows

Top 3 memory consuming processes:

ps() %>%
  top_n(3, rss) %>%
  arrange(desc(rss))
## # A data frame: 3 × 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 64110     1 com.apple… gaborcs… runni… 68283. 7992.  7.39e8 4.29e11 2024-07-17 08:14:51 <ps_handl>
## 2 56754 56683 ark        gaborcs… runni…   813.  112.  5.66e8 4.22e11 2024-08-29 15:04:36 <ps_handl>
## 3 69319     1 Google Ch… gaborcs… runni…   280.   86.9 5.63e8 4.56e11 2024-09-01 07:06:06 <ps_handl>

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 data frame: 3 × 3
##     pid name                                    cpu_time
##   <int> <chr>                                      <dbl>
## 1 64110 com.apple.Virtualization.VirtualMachine   76275.
## 2  3525 Dato                                      12825.
## 3  2617 CursorUIViewService                        6700.

Code of Conduct

Please note that the ps project is released with a Contributor Code of Conduct. By contributing to this project, you agree to abide by its terms.

License

MIT © RStudio