README.md

@@ -4,6 +4,7 @@
 
 [![Build Status](https://travis-ci.org/hakavlad/nohang.svg?branch=master)](https://travis-ci.org/hakavlad/nohang)
 ![CodeQL](https://github.com/hakavlad/nohang/workflows/CodeQL/badge.svg)
+[![Total alerts](https://img.shields.io/lgtm/alerts/g/hakavlad/nohang.svg?logo=lgtm&logoWidth=18)](https://lgtm.com/projects/g/hakavlad/nohang/alerts/)
 [![Packaging status](https://repology.org/badge/tiny-repos/nohang.svg)](https://repology.org/project/nohang/versions)
 
 `nohang` package provides a highly configurable daemon for Linux which is able to correctly prevent [out of memory](https://en.wikipedia.org/wiki/Out_of_memory) (OOM) and keep system responsiveness in low memory conditions.
@@ -43,10 +44,9 @@ Use one of the userspace OOM killers:
 - [systemd-oomd](https://man7.org/linux/man-pages/man8/systemd-oomd.service.8.html): Provided by systemd as `systemd-oomd.service` that uses cgroups-v2 and pressure stall information (PSI) to monitor and take action on processes before an OOM occurs in kernel space. It's used by default on [desktop versions of Fedora 34](https://fedoraproject.org/wiki/Changes/EnableSystemdOomd).
 - [low-memory-monitor](https://gitlab.freedesktop.org/hadess/low-memory-monitor/): There's a [project announcement](http://www.hadess.net/2019/08/low-memory-monitor-new-project.html).
 - [psi-monitor](https://github.com/endlessm/eos-boot-helper/tree/master/psi-monitor): It's used by default on [Endless OS](https://endlessos.com/).
-- `nohang`: nohang is earlyoom on steroids and has many useful features, see below. Maybe this is a good choice for modern desktops and servers if you need fine-tuning. Previously it was used by default on [Garuda Linux](https://garudalinux.org/).
+- `nohang`: nohang is earlyoom on steroids and has many useful features, see below. Maybe this is a good choice for modern desktops and servers if you need fine-tuning. It's used by default on [Garuda Linux](https://garudalinux.org/).
 
 Use these tools to improve responsiveness during heavy swapping:
-- MGLRU patchset is merged in Linux 6.1. Setting `min_ttl_ms` > 50 can help you.
 - [le9-patch](https://github.com/hakavlad/le9-patch): [PATCH] mm: Protect clean file pages under memory pressure to prevent thrashing, avoid high latency and prevent livelock in near-OOM conditions. It's kernel-side solution that can fix the OOM killer behavior.
 - [prelockd](https://github.com/hakavlad/prelockd): Lock executables and shared libraries in memory to improve system responsiveness under low-memory conditions.
 - [memavaild](https://github.com/hakavlad/memavaild): Keep amount of available memory by evicting memory of selected cgroups into swap space.
@@ -118,16 +118,18 @@ To show GUI notifications (optional):
 ## How to install
 
 #### To install on [Fedora](https://src.fedoraproject.org/rpms/nohang/):
-
-Orphaned for 6+ weeks, not available.
+```bash
+$ sudo dnf install nohang-desktop
+$ sudo systemctl enable --now nohang-desktop.service
+```
 
 #### To install on RHEL 7 and RHEL 8:
 
 nohang is avaliable in [EPEL repos](https://fedoraproject.org/wiki/EPEL).
 ```bash
-sudo yum install nohang
-sudo systemctl enable nohang.service
-sudo systemctl start nohang.service
+$ sudo yum install nohang
+$ sudo systemctl enable nohang.service
+$ sudo systemctl start nohang.service
 ```
 To enable PSI on RHEL 8 pass `psi=1` to kernel boot cmdline.
 
@@ -135,18 +137,18 @@ To enable PSI on RHEL 8 pass `psi=1` to kernel boot cmdline.
 
 Use your favorite [AUR helper](https://wiki.archlinux.org/index.php/AUR_helpers). For example,
 ```bash
-yay -S nohang-git
-sudo systemctl enable --now nohang-desktop.service
+$ yay -S nohang-git
+$ sudo systemctl enable --now nohang-desktop.service
 ```
 
 #### To install on Ubuntu 20.04/20.10
 
 To install from [PPA](https://launchpad.net/~oibaf/+archive/ubuntu/test/):
 ```bash
-sudo add-apt-repository ppa:oibaf/test
-sudo apt update
-sudo apt install nohang
-sudo systemctl enable --now nohang-desktop.service
+$ sudo add-apt-repository ppa:oibaf/test
+$ sudo apt update
+$ sudo apt install nohang
+$ sudo systemctl enable --now nohang-desktop.service
 ```
 
 #### To install on Debian and Ubuntu-based systems:
@@ -155,23 +157,23 @@ Outdated and buggy nohang v0.1 release was packaged for [Debian 11](https://pack
 
 It's easy to build a deb package with the latest git snapshot. Install build dependencies:
 ```bash
-sudo apt install make fakeroot
+$ sudo apt install make fakeroot
 ```
 
 Clone the latest git snapshot and run the build script to build the package:
 ```bash
-git clone https://github.com/hakavlad/nohang.git && cd nohang
-deb/build.sh
+$ git clone https://github.com/hakavlad/nohang.git && cd nohang
+$ deb/build.sh
 ```
 
 Install the package:
 ```bash
-sudo apt install --reinstall ./deb/package.deb
+$ sudo apt install --reinstall ./deb/package.deb
 ```
 
 Start and enable `nohang.service` or `nohang-desktop.service` after installing the package:
 ```bash
-sudo systemctl enable --now nohang-desktop.service
+$ sudo systemctl enable --now nohang-desktop.service
 ```
 
 #### To install on Gentoo and derivatives (e.g. Funtoo):
@@ -180,53 +182,53 @@ Add the [eph kit](https://git.sr.ht/~happy_shredder/eph_kit) overlay, for exampl
 Then update your repos:
 
 ```bash
-sudo layman -S # if added via layman
-sudo emerge --sync # local repo on Gentoo
-sudo ego sync # local repo on Funtoo
+$ sudo layman -S # if added via layman
+$ sudo emerge --sync # local repo on Gentoo
+$ sudo ego sync # local repo on Funtoo
 ```
 
 Install:
 
 ```bash
-sudo emerge -a nohang
+$ sudo emerge -a nohang
 ```
 
 Start the service:
 
 ```bash
-sudo rc-service nohang-desktop start
+$ sudo rc-service nohang-desktop start
 ```
 
 Optionally add to startup:
 
 ```bash
-sudo rc-update add nohang-desktop default
+$ sudo rc-update add nohang-desktop default
 ```
 
 #### To install the latest version on any distro:
 ```bash
-git clone https://github.com/hakavlad/nohang.git && cd nohang
-sudo make install
+$ git clone https://github.com/hakavlad/nohang.git && cd nohang
+$ sudo make install
 ```
 
 Config files will be located in `/usr/local/etc/nohang/`. To enable and start unit without GUI notifications:
 ```bash
-sudo systemctl enable --now nohang.service
+$ sudo systemctl enable --now nohang.service
 ```
 
 To enable and start unit with GUI notifications:
 ```bash
-sudo systemctl enable --now nohang-desktop.service
+$ sudo systemctl enable --now nohang-desktop.service
 ```
 
 On systems with OpenRC:
 ```bash
-sudo make install-openrc
+$ sudo make install-openrc
 ```
 
 To uninstall:
 ```bash
-sudo make uninstall
+$ sudo make uninstall
 ```
 
 ## Command line options
@@ -406,11 +408,11 @@ Process with highest badness (found in 55 ms):
 
 To view the latest entries in the log (for systemd users):
 ```bash
-sudo journalctl -eu nohang.service
+$ sudo journalctl -eu nohang.service
 
 #### or
 
-sudo journalctl -eu nohang-desktop.service
+$ sudo journalctl -eu nohang-desktop.service
 ```
 
 You can also enable `separate_log` in the config to logging in `/var/log/nohang/nohang.log`.
@@ -422,7 +424,7 @@ You can also enable `separate_log` in the config to logging in `/var/log/nohang/
 Usage:
 
 ```bash
-oom-sort
+$ oom-sort
 ```
 
 <details>

src/nohang

@@ -7,7 +7,7 @@ from time import sleep, monotonic
 from operator import itemgetter
 from sys import stdout, stderr, argv, exit
 from re import search
-from re import error as invalid_re
+from sre_constants import error as invalid_re
 from signal import signal, SIGKILL, SIGTERM, SIGINT, SIGQUIT, SIGHUP, SIGUSR1
 
 
@@ -165,49 +165,41 @@ def memload():
             os.kill(self_pid, SIGUSR1)
 
 
-def parse_zfs_arcstats():
+def arcstats():
     """
-    Parses '/proc/spl/kstat/zfs/arcstats'.
-    Returns a dictionary with 'name' as keys and 'data' as values.
     """
-    parsed_data = {}
+    with open(arcstats_path, 'rb') as f:
+        a_list = f.read().decode().split('\n')
 
-    with open(arcstats_path, 'r') as as_file:
-        lines = iter(as_file.readlines())
+    for n, line in enumerate(a_list):
+        if n == c_min_index:
+            c_min = int(line.rpartition(' ')[2]) / 1024
+        elif n == size_index:
+            size = int(line.rpartition(' ')[2]) / 1024
 
-        # consume lines until the header row:
-        for line in lines:
-            if 'name' in line and 'data' in line:
-                break
+        elif n == arc_meta_used_index:
+            arc_meta_used = int(line.rpartition(' ')[2]) / 1024
 
-        # Continue iterating over the remaining lines
-        for line in lines:
-            if line.strip():
-                parts = line.split()
-                name = parts[0]
-                data_type = parts[1]
-                data = parts[2]
-                if data_type == '4':
-                    data = int(data)
-                parsed_data[name] = data
+        elif n == arc_meta_min_index:
+            arc_meta_min = int(line.rpartition(' ')[2]) / 1024
 
-    return parsed_data
+        else:
+            continue
 
+    c_rec = size - c_min
 
-def zfs_arc_available():
-    """returns how many KiB of the zfs ARC are reclaimable"""
-    stats = parse_zfs_arcstats()
+    if c_rec < 0:
+        c_rec = 0
 
-    c_rec = max(stats['size'] - stats['c_min'], 0)
+    meta_rec = arc_meta_used - arc_meta_min
 
-    # old zfs: consider arc_meta_used, arc_meta_min
-    if 'arc_meta_used' in stats and 'arc_meta_min' in stats:
-        meta_rec = max(stats['arc_meta_used'] - stats['arc_meta_min'], 0)
-        return (c_rec + meta_rec) / 1024
+    if meta_rec < 0:
+        meta_rec = 0
+    zfs_available = c_rec + meta_rec
 
-    # new zfs: metadata is no longer accounted for separately,
-    # https://github.com/openzfs/zfs/commit/a8d83e2a24de6419dc58d2a7b8f38904985726cb
-    return c_rec / 1024
+    # return c_min, size, arc_meta_used, arc_meta_min, zfs_available
+
+    return zfs_available
 
 
 def exe(cmd):
@@ -217,7 +209,7 @@ def exe(cmd):
 
     cmd_num_dict['cmd_num'] += 1
     cmd_num = cmd_num_dict['cmd_num']
-    th_name = threading.current_thread().name
+    th_name = threading.current_thread().getName()
 
     log('Executing Command-{} {} with timeout {}s in {}'.format(
         cmd_num,
@@ -245,11 +237,11 @@ def start_thread(func, *a, **k):
     """ run function in a new thread
     """
     th = threading.Thread(target=func, args=a, kwargs=k, daemon=True)
-    th_name = th.name
+    th_name = th.getName()
 
     if debug_threading:
         log('Starting {} from {}'.format(
-            th_name, threading.current_thread().name
+            th_name, threading.current_thread().getName()
         ))
 
     try:
@@ -358,7 +350,7 @@ def pop(cmd):
     else:
         wait_time = 30
 
-    th_name = threading.current_thread().name
+    th_name = threading.current_thread().getName()
 
     log('Executing Command-{} {} with timeout {}s in {}'.format(
         cmd_num,
@@ -1349,7 +1341,7 @@ def check_mem_and_swap():
     sf = int(m_list[swap_free_index].split(':')[1])
 
     if ZFS:
-        ma += zfs_arc_available()
+        ma += arcstats()
 
     return ma, st, sf
 
@@ -1377,7 +1369,7 @@ def meminfo():
     md['available'] = mem_available
 
     if ZFS:
-        z = zfs_arc_available()
+        z = arcstats()
         mem_available += z
 
     md['shared'] = shmem
@@ -3703,7 +3695,7 @@ if 'max_victim_ancestry_depth' in config_dict:
         errprint('Invalid max_victim_ancestry_depth value, not integer\nExit')
         exit(1)
     if max_victim_ancestry_depth < 1:
-        errprint('Invalid max_victim_ancestry_depth value\nExit')
+        errprint('Invalud max_victim_ancestry_depth value\nExit')
         exit(1)
 else:
     missing_config_key('max_victim_ancestry_depth')
@@ -3966,6 +3958,29 @@ if check_kmsg:
 if ZFS:
     log('WARNING: ZFS found. Available memory will not be calculated '
         'correctly (issue#89)')
+    try:
+        # find indexes
+        with open(arcstats_path, 'rb') as f:
+            a_list = f.read().decode().split('\n')
+        for n, line in enumerate(a_list):
+            if line.startswith('c_min '):
+                c_min_index = n
+
+            elif line.startswith('size '):
+                size_index = n
+
+            elif line.startswith('arc_meta_used '):
+                arc_meta_used_index = n
+
+            elif line.startswith('arc_meta_min '):
+                arc_meta_min_index = n
+
+            else:
+                continue
+    except Exception as e:
+        log(e)
+        ZFS = False
+
 
 while True: