From 1d47c766519ed47e2b3f2020e55be87435d6f886 Mon Sep 17 00:00:00 2001
From: Henrik Nygren <nygrenh@gmail.com>
Date: Tue, 8 Oct 2024 14:10:13 +0300
Subject: [PATCH] Add a script for cleaning passenger workers

---
 script/passenger_worker_cleaner.rb | 221 +++++++++++++++++++++++++++++
 1 file changed, 221 insertions(+)
 create mode 100644 script/passenger_worker_cleaner.rb

diff --git a/script/passenger_worker_cleaner.rb b/script/passenger_worker_cleaner.rb
new file mode 100644
index 000000000..c5948cf50
--- /dev/null
+++ b/script/passenger_worker_cleaner.rb
@@ -0,0 +1,221 @@
+#!/usr/bin/env ruby
+# frozen_string_literal: true
+
+require 'open3'
+
+# Configuration Constants
+PASSENGER_STATUS_CMD = 'passenger-status'
+MIN_WORKERS_ALLOWED = 4
+LAST_USED_THRESHOLD_SECONDS = 10 * 60  # 10 minutes
+
+# Class representing a single Passenger Worker Process
+class WorkerProcess
+  attr_reader :pid, :sessions, :processed, :uptime_seconds, :cpu, :memory_mb, :last_used_seconds
+
+  def initialize(pid:, sessions:, processed:, uptime_str:, cpu:, memory_str:, last_used_str:)
+    @pid = pid
+    @sessions = sessions
+    @processed = processed
+    @uptime_seconds = parse_time(uptime_str)
+    @cpu = cpu
+    @memory_mb = parse_memory(memory_str)
+    @last_used_seconds = parse_time(last_used_str)
+  end
+
+  # Parses a time string like "16m 52s" into total seconds
+  def parse_time(time_str)
+    total_seconds = 0
+    # Match patterns like "16m", "52s", etc.
+    time_str.scan(/(\d+)m|(\d+)s/) do |min, sec|
+      total_seconds += min.to_i * 60 if min
+      total_seconds += sec.to_i if sec
+    end
+    total_seconds
+  end
+
+  # Parses memory string like "184M", "1.2G", "512K" into integer megabytes
+  def parse_memory(mem_str)
+    match = mem_str.strip.match(/^([\d.]+)([KMGTP])?$/i)
+    return 0 unless match
+
+    value = match[1].to_f
+    unit = match[2]&.upcase || 'M'
+
+    case unit
+    when 'K'
+      (value / 1024).round(2)
+    when 'M'
+      value.round(2)
+    when 'G'
+      (value * 1024).round(2)
+    when 'T'
+      (value * 1024 * 1024).round(2)
+    when 'P'
+      (value * 1024 * 1024 * 1024).round(2)
+    else
+      value.round(2)
+    end
+  end
+
+  def to_s
+    "PID: #{@pid}, Last Used: #{@last_used_seconds}s, Memory: #{@memory_mb} MB"
+  end
+end
+
+# Class responsible for executing and parsing passenger-status output
+class PassengerStatusParser
+  attr_reader :total_processes, :workers
+
+  def initialize(command: PASSENGER_STATUS_CMD)
+    @command = command
+    @total_processes = 0
+    @workers = []
+  end
+
+  def execute
+    stdout, stderr, status = Open3.capture3(@command)
+
+    unless status.success?
+      raise "Error executing #{@command}: #{stderr}"
+    end
+
+    parse(stdout)
+  end
+
+  private
+    def parse(output)
+      current_worker_data = {}
+      in_app_group = false
+
+      output.each_line do |line|
+        line = line.strip
+
+        # Capture total processes
+        if line.start_with?('Processes :')
+          @total_processes = line.split(':').last.strip.to_i
+        end
+
+        # Detect start of Application groups
+        if line.start_with?('----------- Application groups -----------')
+          in_app_group = true
+          next
+        end
+
+        next unless in_app_group
+
+        # Start of a worker entry
+        if line.start_with?('* PID:')
+          # Save previous worker if exists
+          if current_worker_data.any?
+            @workers << build_worker(current_worker_data)
+            current_worker_data = {}
+          end
+
+          # Extract PID, Sessions, Processed, Uptime
+          pid_match = line.match(/\* PID:\s*(\d+)\s+Sessions:\s*(\d+)\s+Processed:\s*(\d+)\s+Uptime:\s*([\dm\s]+s)/)
+          if pid_match
+            current_worker_data[:pid] = pid_match[1].to_i
+            current_worker_data[:sessions] = pid_match[2].to_i
+            current_worker_data[:processed] = pid_match[3].to_i
+            current_worker_data[:uptime_str] = pid_match[4].strip
+          end
+        elsif line.start_with?('CPU:')
+          # Extract CPU and Memory
+          cpu_match = line.match(/CPU:\s*([\d.]+)%/)
+          memory_match = line.match(/Memory\s*:\s*([\d.]+[KMGTP]?)/)
+          current_worker_data[:cpu] = cpu_match[1].to_f if cpu_match
+          current_worker_data[:memory_str] = memory_match[1] if memory_match
+        elsif line.start_with?('Last used:')
+          # Extract Last used
+          last_used_match = line.match(/Last used:\s*([\dm\s]+s)\s*(?:ago|ag)?/)
+          if last_used_match
+            current_worker_data[:last_used_str] = last_used_match[1].strip
+          end
+        end
+      end
+
+      # Add the last worker if exists
+      if current_worker_data.any?
+        @workers << build_worker(current_worker_data)
+      end
+    end
+
+    def build_worker(data)
+      WorkerProcess.new(
+        pid: data[:pid],
+        sessions: data[:sessions],
+        processed: data[:processed],
+        uptime_str: data[:uptime_str],
+        cpu: data[:cpu],
+        memory_str: data[:memory_str],
+        last_used_str: data[:last_used_str]
+      )
+    end
+end
+
+# Class responsible for managing Passenger Workers
+class PassengerWorkerManager
+  def initialize(parser: PassengerStatusParser.new)
+    @parser = parser
+  end
+
+  def run
+    begin
+      @parser.execute
+    rescue => e
+      puts e.message
+      exit 1
+    end
+
+    total_processes = @parser.total_processes
+    workers = @parser.workers
+
+    puts "Total Processes: #{total_processes}"
+    puts "Total Workers: #{workers.size}"
+
+    if total_processes > MIN_WORKERS_ALLOWED
+      puts "Number of processes (#{total_processes}) exceeds the minimum allowed (#{MIN_WORKERS_ALLOWED})."
+
+      worker_to_kill = find_worker_to_kill(workers)
+
+      if worker_to_kill
+        pid = worker_to_kill.pid
+        last_used_seconds = worker_to_kill.last_used_seconds
+        last_used_minutes = (last_used_seconds / 60).to_i
+        last_used_seconds_remainder = last_used_seconds % 60
+
+        puts "Killing worker PID #{pid} with last used time of #{last_used_minutes}m #{last_used_seconds_remainder}s and memory: #{worker_to_kill.memory_mb} MB."
+
+        kill_worker(pid)
+      else
+        puts "No workers have been idle for more than #{LAST_USED_THRESHOLD_SECONDS / 60} minutes."
+      end
+    else
+      puts "Number of processes (#{total_processes}) is under (#{MIN_WORKERS_ALLOWED}). No action needed."
+    end
+  end
+
+  private
+    def find_worker_to_kill(workers)
+      eligible_workers = workers.select { |w| w.last_used_seconds > LAST_USED_THRESHOLD_SECONDS }
+
+      return nil if eligible_workers.empty?
+
+      # Find the worker with the maximum last used time
+      eligible_workers.max_by { |w| w.last_used_seconds }
+    end
+
+    def kill_worker(pid)
+      Process.kill('TERM', pid)
+      puts "Successfully sent TERM signal to PID #{pid}."
+    rescue Errno::ESRCH
+      puts "Process with PID #{pid} does not exist."
+    rescue Errno::EPERM
+      puts "Insufficient permissions to kill PID #{pid}."
+    rescue => e
+      puts "Failed to kill PID #{pid}: #{e.message}"
+    end
+end
+
+manager = PassengerWorkerManager.new
+manager.run