Add option -g: Kill processes in a process group

#247

Author: TaWeiTu

MANPAGE.md

@@ -104,6 +104,27 @@ When earlyoom is run through its default systemd service, the `-p` switch doesn'
 #### -n
 Enable notifications via d-bus.
 
+#### -g
+Kill all processes that have same process group id (PGID) as the process
+with excessive memory usage.
+
+For example, with this flag turned on, the whole application will be killed when
+one of its subprocess consumes too much memory (as long as they all have the
+same PGID, of course).
+
+Enable this flag when completely cleaning up the "entire application" is more desirable,
+and you are sure that the application puts all its processes in the same PGID.
+
+Note that some desktop environments (GNOME, for example) put all desktop
+application in the same process group as `gnome-shell`. earlyoom might kill
+all such processes including `gnome-shell` when this flag is turned on.
+
+Be sure to check how your environment behaves beforehand. Use
+
+	pstree -gT
+
+to show all processes with the PGID in brackets.
+
 #### \-\-prefer REGEX
 prefer killing processes matching REGEX (adds 300 to oom_score)
 

README.md

@@ -245,6 +245,7 @@ Usage: ./earlyoom [OPTION]...
   -i                        user-space oom killer should ignore positive
                             oom_score_adj values
   -n                        enable d-bus notifications
+  -g                        kill all processes within a process group
   -d                        enable debugging messages
   -v                        print version information and exit
   -r INTERVAL               memory report interval in seconds (default 1), set

kill.c

@@ -73,6 +73,14 @@ int kill_wait(const poll_loop_args_t* args, pid_t pid, int sig)
     }
     meminfo_t m = { 0 };
     const unsigned poll_ms = 100;
+    if (args->kill_process_group) {
+        int res = getpgid(pid);
+        if (res < 0) {
+            return res;
+        }
+        pid = -res;
+        warn("killing whole process group %d (-g flag is active)\n", pid);
+    }
     int res = kill(pid, sig);
     if (res != 0) {
         return res;

kill.h

@@ -18,6 +18,8 @@ typedef struct {
     bool ignore_oom_score_adj;
     /* send d-bus notifications? */
     bool notify;
+    /* kill all processes within a process group */
+    bool kill_process_group;
     /* prefer/avoid killing these processes. NULL = no-op. */
     regex_t* prefer_regex;
     regex_t* avoid_regex;

main.c

@@ -101,7 +101,7 @@ int main(int argc, char* argv[])
     meminfo_t m = parse_meminfo();
 
     int c;
-    const char* short_opt = "m:s:M:S:kinN:dvr:ph";
+    const char* short_opt = "m:s:M:S:kingN:dvr:ph";
     struct option long_opt[] = {
         { "prefer", required_argument, NULL, LONG_OPT_PREFER },
         { "avoid", required_argument, NULL, LONG_OPT_AVOID },
@@ -173,6 +173,9 @@ int main(int argc, char* argv[])
             args.notify = true;
             fprintf(stderr, "Notifying through D-Bus\n");
             break;
+        case 'g':
+            args.kill_process_group = true;
+            break;
         case 'N':
             args.notify = true;
             fprintf(stderr, "Notifying through D-Bus, argument '%s' ignored for compatability\n", optarg);
@@ -220,6 +223,7 @@ int main(int argc, char* argv[])
                 "  -i                        user-space oom killer should ignore positive\n"
                 "                            oom_score_adj values\n"
                 "  -n                        enable d-bus notifications\n"
+                "  -g                        kill all processes within a process group\n"
                 "  -d                        enable debugging messages\n"
                 "  -v                        print version information and exit\n"
                 "  -r INTERVAL               memory report interval in seconds (default 1), set\n"