fix low mem warn slowdown

Makefile

@@ -8,6 +8,9 @@ install:
 	install -d $(DESTDIR)/$(PREFIX)/usr/sbin
 	install -m0755 ./nohang $(DESTDIR)/$(PREFIX)/usr/sbin/nohang
 	
+	install -d $(DESTDIR)/$(PREFIX)/usr/sbin
+	install -m0755 ./nohang_notify_low_mem $(DESTDIR)/$(PREFIX)/usr/sbin/nohang_notify_low_mem
+	
 	install -d $(DESTDIR)/$(PREFIX)/etc/nohang
 	install -m0644 ./nohang.conf $(DESTDIR)/$(PREFIX)/etc/nohang
 	install -m0644 ./default_values_backup.conf $(DESTDIR)/$(PREFIX)/etc/nohang
@@ -23,6 +26,7 @@ uninstall:
 	# 'make uninstall' must not fail with error if systemctl is unavailable or returns error
 	systemctl disable nohang.service || true
 	rm -fv $(PREFIX)/usr/sbin/nohang
+	rm -fv $(PREFIX)/usr/sbin/nohang_notify_low_mem
 	rm -fv $(PREFIX)/usr/share/man/man1/nohang.1.gz
 	rm -fv $(PREFIX)/lib/systemd/system/nohang.service
 	rm -fvr $(PREFIX)/etc/nohang/

nohang

@@ -204,35 +204,33 @@ def pid_to_name(pid):
 
 def send_notify_warn():
 
+    # find process with max badness
     fat_tuple = fattest()
+    pid = fat_tuple[1]
+    name = fat_tuple[0]
 
     if mem_used_zram > 0:
-        title = 'Low memory: {}% {}% {}%'.format(
+        low_mem_percent = '{}% {}% {}%'.format(
             round(mem_available / mem_total * 100),
             round(swap_free / (swap_total + 0.1) * 100),
             round(mem_used_zram / mem_total * 100))
     elif swap_free > 0:
-        title = 'Low memory: {}% {}%'.format(
+        low_mem_percent = '{}% {}%'.format(
             round(mem_available / mem_total * 100),
             round(swap_free / (swap_total + 0.1) * 100))
     else:
-        title = 'Low memory: {}%'.format(
+        low_mem_percent = '{}%'.format(
             round(mem_available / mem_total * 100))
 
-    body = 'Fattest process: <b>{}</b>, <b>{}</b>'.format(fat_tuple[1], fat_tuple[0])
+    title = 'Low memory: {}'.format(low_mem_percent)
+    body = 'Fattest process: <b>{}</b>, <b>{}</b>'.format(pid, name)
 
     if root:
-        # отправляем уведомление всем залогиненным пользователям
+        # send notification to all active users
-        b = root_notify_env()
+        Popen(['/usr/sbin/nohang_notify_low_mem', '--mem', low_mem_percent, '--pid', pid, '--name', name])
-        if len(b) > 0:
-            for i in b:
-                username, display_env, dbus_env = i[0], i[1], i[2]
-                Popen(['sudo', '-u', username, 'env', display_env,
-                       dbus_env, 'notify-send', '--icon=dialog-warning',
-                       '{}'.format(title), '{}'.format(body)])
     else:
         # отправляем уведомление пользователю, который запустил nohang
-        Popen(['notify-send', '--icon=dialog-warning', '{}'.format(title), '{}'.format(body)])
+        Popen(['notify-send', '--icon=dialog-warning', 'Low memory: {}'.format(title), '{}'.format(body)])
 
 
 def send_notify(signal, name, pid):
@@ -1515,4 +1513,3 @@ while True:
         stdout.flush()
 
         sleep_after_check_mem()
-

nohang_notify_low_mem

@@ -0,0 +1,87 @@
+#!/usr/bin/env python3
+
+# notify_low_mem --mem '14% 12%' --name 'stress' --pid '6666'
+
+# output:
+# Low memory: 14% 12%
+# Fattest process: 6666, stress
+
+from argparse import ArgumentParser
+from subprocess import Popen, PIPE
+
+parser = ArgumentParser()
+
+parser.add_argument(
+    '--mem',
+    help="""available memory percent (15%, for example)""",
+    default=None,
+    type=str
+)
+
+parser.add_argument(
+    '--pid',
+    help="""pid""",
+    default=None,
+    type=str
+)
+
+parser.add_argument(
+    '--name',
+    help="""process name""",
+    default=None,
+    type=str
+)
+
+args = parser.parse_args()
+
+pid = args.pid
+name = args.name
+mem = args.mem
+
+title = 'Low memory: {}'.format(mem)
+
+body = 'Fattest process: <b>{}</b>, <b>{}</b>'.format(pid, name)
+
+# return list of tuples with
+# username, DISPLAY and DBUS_SESSION_BUS_ADDRESS
+def root_notify_env():
+
+    ps_output_list = Popen(['ps', 'ae'], stdout=PIPE
+        ).communicate()[0].decode().split('\n')
+
+    lines_with_displays = []
+    for line in ps_output_list:
+        if ' DISPLAY=' in line and ' DBUS_SESSION_BUS_ADDRES' \
+            'S=' in line and ' USER=' in line:
+            lines_with_displays.append(line)
+
+    # list of tuples with needments
+    deus = []
+    for i in lines_with_displays:
+        for i in i.split(' '):
+            if i.startswith('USER='):
+                user = i.strip('\n').split('=')[1]
+                continue
+            if i.startswith('DISPLAY='):
+                disp_value = i.strip('\n').split('=')[1][0:2]
+                disp = 'DISPLAY=' + disp_value
+                continue
+            if i.startswith('DBUS_SESSION_BUS_ADDRESS='):
+                dbus = i.strip('\n')
+        deus.append(tuple([user, disp, dbus]))
+
+    # unique list of tuples
+    vult = []
+    for user_env_tuple in set(deus):
+        vult.append(user_env_tuple)
+
+    return vult
+
+b = root_notify_env()
+
+if len(b) > 0:
+    for i in b:
+        username, display_env, dbus_env = i[0], i[1], i[2]
+        Popen(['sudo', '-u', username, 'env', display_env,
+                dbus_env, 'notify-send', '--icon=dialog-warning',
+                '{}'.format(title), '{}'.format(body)])