class DaemonController

Main daemon controller object. See the README for an introduction and tutorial.

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the “Software”), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

Constants

ALLOWED_CONNECT_EXCEPTIONS
MAJOR
MINOR
SPAWNER_FILE
TINY
VERSION_STRING

Public Class Methods

can_ping_unix_sockets?() click to toggle source

Checks whether ping Unix domain sockets is supported. Currently this is supported on all Ruby implementations, except JRuby.

# File lib/daemon_controller.rb, line 342
def self.can_ping_unix_sockets?
        return RUBY_PLATFORM != "java"
end

new(options) click to toggle source

Create a new DaemonController object.

Mandatory options¶ ↑

:identifier

A human-readable, unique name for this daemon, e.g. “Sphinx search server”. This identifier will be used in some error messages. On some platforms, it will be used for concurrency control: on such platforms, no two DaemonController objects will operate on the same identifier on the same time.

:start_command

The command to start the daemon. This must be a a String, e.g. “mongrel_rails start -e production”, or a Proc which returns a String.

If the value is a Proc, and the before_start option is given too, then the start_command Proc is guaranteed to be called after the before_start Proc is called.

:ping_command

The ping command is used to check whether the daemon can be connected to. It is also used to ensure that start only returns when the daemon can be connected to.

The value may be a command string. This command must exit with an exit code of 0 if the daemon can be successfully connected to, or exit with a non-0 exit code on failure.

The value may also be an Array which specifies the socket address of the daemon. It must be in one of the following forms:

:tcp, host_name, port
:unix, filename

The value may also be a Proc, which returns an expression that evaluates to true (indicating that the daemon can be connected to) or false (failure). If the Proc raises Errno::ECONNREFUSED, Errno::ENETUNREACH, Errno::ETIMEDOUT Errno::ECONNRESET, Errno::EINVAL or Errno::EADDRNOTAVAIL then that also means that the daemon cannot be connected to. NOTE: if the ping command returns an object which responds to #close, then that method will be called on it. This makes it possible to specify a ping command such as lambda { TCPSocket.new('localhost', 1234) }, without having to worry about closing it afterwards. Any exceptions raised by close are ignored.

:pid_file

The PID file that the daemon will write to. Used to check whether the daemon is running.

:lock_file

The lock file to use for serializing concurrent daemon management operations. Defaults to “(filename of PID file).lock”.

:log_file

The log file that the daemon will write to. It will be consulted to see whether the daemon has printed any error messages during startup.

Optional options¶ ↑

:stop_command

A command to stop the daemon with, e.g. “/etc/rc.d/nginx stop”. If no stop command is given (i.e. nil), then DaemonController will stop the daemon by killing the PID written in the PID file.

The default value is nil.

:restart_command

A command to restart the daemon with, e.g. “/etc/rc.d/nginx restart”. If no restart command is given (i.e. nil), then DaemonController will restart the daemon by calling stop and start.

The default value is nil.

:before_start

This may be a Proc. It will be called just before running the start command. The #before_start proc is not subject to the start timeout.

:start_timeout

The maximum amount of time, in seconds, that start may take to start the daemon. Since start also waits until the daemon can be connected to, that wait time is counted as well. If the daemon does not start in time, then start will raise an exception.

The default value is 15.

:stop_timeout

The maximum amount of time, in seconds, that stop may take to stop the daemon. Since stop also waits until the daemon is no longer running, that wait time is counted as well. If the daemon does not stop in time, then stop will raise an exception.

The default value is 15.

:log_file_activity_timeout

Once a daemon has gone into the background, it will become difficult to know for certain whether it is still initializing or whether it has failed and exited, until it has written its PID file. Suppose that it failed with an error after daemonizing but before it has written its PID file; not many system administrators want to wait 15 seconds (the default start timeout) to be notified of whether the daemon has terminated with an error.

An alternative way to check whether the daemon has terminated with an error, is by checking whether its log file has been recently updated. If, after the daemon has started, the log file hasn't been updated for the amount of seconds given by the :log_file_activity_timeout option, then the daemon is assumed to have terminated with an error.

The default value is 7.

:daemonize_for_me

Normally daemon_controller will wait until the daemon has daemonized into the background, in order to capture any errors that it may print on stdout or stderr before daemonizing. However, if the daemon doesn't support daemonization for some reason, then setting this option to true will cause daemon_controller to do the daemonization for the daemon.

The default is false.

:keep_ios

Upon spawning the daemon, daemon_controller will normally close all file descriptors except stdin, stdout and stderr. However if there are any file descriptors you want to keep open, specify the IO objects here. This must be an array of IO objects.

:env

This must be a Hash. The hash will contain the environment variables available to be made available to the daemon. Hash keys must be strings, not symbols.

# File lib/daemon_controller.rb, line 185
def initialize(options)
        [:identifier, :start_command, :ping_command, :pid_file, :log_file].each do |option|
                if !options.has_key?(option)
                        raise ArgumentError, "The ':#{option}' option is mandatory."
                end
        end
        @identifier = options[:identifier]
        @start_command = options[:start_command]
        @stop_command = options[:stop_command]
        @ping_command = options[:ping_command]
        @restart_command = options[:restart_command]
        @ping_interval = options[:ping_interval] || 0.1
        @pid_file = options[:pid_file]
        @log_file = options[:log_file]
        @before_start = options[:before_start]
        @start_timeout = options[:start_timeout] || 15
        @stop_timeout = options[:stop_timeout] || 15
        @log_file_activity_timeout = options[:log_file_activity_timeout] || 7
        @daemonize_for_me = options[:daemonize_for_me]
        @keep_ios = options[:keep_ios] || []
        @lock_file = determine_lock_file(options, @identifier, @pid_file)
        @env = options[:env] || {}
end

Private Class Methods

fork_supported?() click to toggle source

# File lib/daemon_controller.rb, line 586
def self.fork_supported?
        return RUBY_PLATFORM != "java" && RUBY_PLATFORM !~ /win32/
end

spawn_supported?() click to toggle source

# File lib/daemon_controller.rb, line 590
def self.spawn_supported?
        # Process.spawn doesn't work very well in JRuby.
        return Process.respond_to?(:spawn) && RUBY_PLATFORM != "java"
end

Public Instance Methods

connect() { || ... } click to toggle source

Connect to the daemon by running the given block, which contains the connection logic. If the daemon isn't already running, then it will be started.

The block must return nil or raise Errno::ECONNREFUSED, Errno::ENETUNREACH, Errno::ETIMEDOUT, Errno::ECONNRESET, Errno::EINVAL and Errno::EADDRNOTAVAIL to indicate that the daemon cannot be connected to. It must return non-nil if the daemon can be connected to. Upon successful connection, the return value of the block will be returned by connect.

Note that the block may be called multiple times.

Raises:

StartError - an attempt to start the daemon was made, but the start command failed with an error.
StartTimeout - an attempt to start the daemon was made, but the daemon did not start in time, or it failed after it has gone into the background.
ConnectError - the daemon wasn't already running, but we couldn't connect to the daemon even after starting it.

# File lib/daemon_controller.rb, line 242
def connect
        connection = nil
        @lock_file.shared_lock do
                begin
                        connection = yield
                rescue *ALLOWED_CONNECT_EXCEPTIONS
                        connection = nil
                end
        end
        if connection.nil?
                @lock_file.exclusive_lock do
                        if !daemon_is_running?
                                start_without_locking
                        end
                        connect_exception = nil
                        begin
                                connection = yield
                        rescue *ALLOWED_CONNECT_EXCEPTIONS => e
                                connection = nil
                                connect_exception = e
                        end
                        if connection.nil?
                                # Daemon is running but we couldn't connect to it. Possible
                                # reasons:
                                # - The daemon froze.
                                # - Bizarre security restrictions.
                                # - There's a bug in the yielded code.
                                if connect_exception
                                        raise ConnectError, "Cannot connect to the daemon: #{connect_exception} (#{connect_exception.class})"
                                else
                                        raise ConnectError, "Cannot connect to the daemon"
                                end
                        else
                                return connection
                        end
                end
        else
                return connection
        end
end

pid() click to toggle source

Returns the daemon's PID, as reported by its PID file. Returns the PID as an integer, or nil there is no valid PID in the PID file.

This method doesn't check whether the daemon's actually running. Use running? if you want to check whether it's actually running.

Raises SystemCallError or IOError if something went wrong during reading of the PID file.

# File lib/daemon_controller.rb, line 322
def pid
        @lock_file.shared_lock do
                return read_pid_file
        end
end

restart() click to toggle source

Restarts the daemon. Uses the restart_command if provided, otherwise calls stop and start.

# File lib/daemon_controller.rb, line 305
def restart
        if @restart_command
                run_command(@restart_command)
        else
                stop
                start
        end
end

running?() click to toggle source

Checks whether the daemon is still running. This is done by reading the PID file and then checking whether there is a process with that PID.

Raises SystemCallError or IOError if something went wrong during reading of the PID file.

# File lib/daemon_controller.rb, line 334
def running?
        @lock_file.shared_lock do
                return daemon_is_running?
        end
end

start() click to toggle source

Start the daemon and wait until it can be pinged.

Raises:

AlreadyStarted - the daemon is already running.
StartError - the start command failed.
StartTimeout - the daemon did not start in time. This could also mean that the daemon failed after it has gone into the background.

# File lib/daemon_controller.rb, line 216
def start
        @lock_file.exclusive_lock do
                start_without_locking
        end
end

stop() click to toggle source

Stop the daemon and wait until it has exited.

Raises:

StopError - the stop command failed.
StopTimeout - the daemon didn't stop in time.

# File lib/daemon_controller.rb, line 288
def stop
        @lock_file.exclusive_lock do
                begin
                        Timeout.timeout(@stop_timeout, Timeout::Error) do
                                kill_daemon
                                wait_until do
                                        !daemon_is_running?
                                end
                        end
                rescue Timeout::Error
                        raise StopTimeout, "Daemon '#{@identifier}' did not exit in time"
                end
        end
end

Private Instance Methods

before_start() click to toggle source

# File lib/daemon_controller.rb, line 414
def before_start
        if @before_start
                @before_start.call
        end
end

check_pid(pid) click to toggle source

# File lib/daemon_controller.rb, line 485
def check_pid(pid)
        Process.kill(0, pid)
        return true
rescue Errno::ESRCH
        return false
rescue Errno::EPERM
        # We didn't have permission to kill the process. Either the process
        # is owned by someone else, or the system has draconian security
        # settings and we aren't allowed to kill *any* process. Assume that
        # the process is running.
        return true
end

daemon_is_running?() click to toggle source

# File lib/daemon_controller.rb, line 452
def daemon_is_running?
        begin
                pid = read_pid_file
        rescue Errno::ENOENT
                # The PID file may not exist, or another thread/process
                # executing #running? may have just deleted the PID file.
                # So we catch this error.
                pid = nil
        end
        if pid.nil?
                return false
        elsif check_pid(pid)
                return true
        else
                delete_pid_file
                return false
        end
end

daemonization_timed_out() click to toggle source

This method does nothing and only serves as a hook for the unit test.

# File lib/daemon_controller.rb, line 536
def daemonization_timed_out
end

delete_pid_file() click to toggle source

# File lib/daemon_controller.rb, line 480
def delete_pid_file
        File.unlink(@pid_file)
rescue Errno::EPERM, Errno::EACCES, Errno::ENOENT # ignore
end

determine_lock_file(options, identifier, pid_file) click to toggle source

# File lib/daemon_controller.rb, line 578
def determine_lock_file(options, identifier, pid_file)
        if options[:lock_file]
                return LockFile.new(File.expand_path(options[:lock_file]))
        else
                return LockFile.new(File.expand_path(pid_file + ".lock"))
        end
end

differences_in_log_file() click to toggle source

# File lib/daemon_controller.rb, line 560
def differences_in_log_file
        if @original_log_file_stat
                File.open(@log_file, 'r') do |f|
                        f.seek(@original_log_file_stat.size, IO::SEEK_SET)
                        diff = f.read.strip
                        if diff.empty?
                                return nil
                        else
                                return diff
                        end
                end
        else
                return nil
        end
rescue Errno::ENOENT
        return nil
end

interruptable_waitpid(pid) click to toggle source

# File lib/daemon_controller.rb, line 847
def interruptable_waitpid(pid)
        Process.waitpid(pid)
end

kill_daemon() click to toggle source

# File lib/daemon_controller.rb, line 428
def kill_daemon
        if @stop_command
                begin
                        run_command(@stop_command)
                rescue StartError => e
                        raise StopError, e.message
                end
        else
                kill_daemon_with_signal
        end
end

kill_daemon_with_signal(force = false) click to toggle source

# File lib/daemon_controller.rb, line 440
def kill_daemon_with_signal(force = false)
        pid = read_pid_file
        if pid
                if force
                        Process.kill('SIGKILL', pid)
                else
                        Process.kill('SIGTERM', pid)
                end
        end
rescue Errno::ESRCH, Errno::ENOENT
end

log_file_has_changed?() click to toggle source

# File lib/daemon_controller.rb, line 544
def log_file_has_changed?
        if @current_log_file_stat
                stat = File.stat(@log_file) rescue nil
                if stat
                        result = @current_log_file_stat.mtime != stat.mtime ||
                                 @current_log_file_stat.size  != stat.size
                        @current_log_file_stat = stat
                        return result
                else
                        return true
                end
        else
                return false
        end
end

no_activity?(seconds) click to toggle source

Check whether there has been no recorded activity in the past seconds seconds.

# File lib/daemon_controller.rb, line 523
def no_activity?(seconds)
        return Time.now - @last_activity_time > seconds
end

pid_file_available?() click to toggle source

# File lib/daemon_controller.rb, line 527
def pid_file_available?
        return File.exist?(@pid_file) && File.stat(@pid_file).size != 0
end

ping_socket(host_name, port) click to toggle source

# File lib/daemon_controller.rb, line 736
def ping_socket(host_name, port)
        channel = java.nio.channels.SocketChannel.open
        begin
                address = java.net.InetSocketAddress.new(host_name, port)
                channel.configure_blocking(false)
                if channel.connect(address)
                        return true
                end

                deadline = Time.now.to_f + 0.1
                done = false
                while true
                        begin
                                if channel.finish_connect
                                        return true
                                end
                        rescue java.net.ConnectException => e
                                if e.message =~ /Connection refused/i
                                        return false
                                else
                                        throw e
                                end
                        end
                        
                        # Not done connecting and no error.
                        sleep 0.01
                        if Time.now.to_f >= deadline
                                return false
                        end
                end
        ensure
                channel.close
        end
end

read_pid_file() click to toggle source

# File lib/daemon_controller.rb, line 471
def read_pid_file
        pid = File.read(@pid_file).strip
        if pid =~ /\A\d+\Z/
                return pid.to_i
        else
                return nil
        end
end

record_activity() click to toggle source

# File lib/daemon_controller.rb, line 518
def record_activity
        @last_activity_time = Time.now
end

ruby_interpreter() click to toggle source

# File lib/daemon_controller.rb, line 801
def ruby_interpreter
        if defined?(RbConfig)
                rb_config = RbConfig::CONFIG
        else
                rb_config = Config::CONFIG
        end
        File.join(
                rb_config['bindir'],
                rb_config['RUBY_INSTALL_NAME']
        ) + rb_config['EXEEXT']
end

run_command(command) click to toggle source

# File lib/daemon_controller.rb, line 595
def run_command(command)
        # Create tempfile for storing the command's output.
        tempfile = Tempfile.new('daemon-output')
        tempfile_path = tempfile.path
        File.chmod(0666, tempfile_path)
        tempfile.close
        
        if self.class.fork_supported? || self.class.spawn_supported?
                if Process.respond_to?(:spawn)
                        options = {
                                :in  => "/dev/null",
                                :out => tempfile_path,
                                :err => tempfile_path,
                                :close_others => true
                        }
                        @keep_ios.each do |io|
                                options[io] = io
                        end
                        if @daemonize_for_me
                                pid = Process.spawn(@env, ruby_interpreter, SPAWNER_FILE,
                                        command, options)
                        else
                                pid = Process.spawn(@env, command, options)
                        end
                else
                        pid = safe_fork(@daemonize_for_me) do
                                ObjectSpace.each_object(IO) do |obj|
                                        if !@keep_ios.include?(obj)
                                                obj.close rescue nil
                                        end
                                end
                                STDIN.reopen("/dev/null", "r")
                                STDOUT.reopen(tempfile_path, "w")
                                STDERR.reopen(tempfile_path, "w")
                                ENV.update(@env)
                                exec(command)
                        end
                end
                
                # run_command might be running in a timeout block (like
                # in #start_without_locking).
                begin
                        interruptable_waitpid(pid)
                rescue Errno::ECHILD
                        # Maybe a background thread or whatever waitpid()'ed
                        # this child process before we had the chance. There's
                        # no way to obtain the exit status now. Assume that
                        # it started successfully; if it didn't we'll know
                        # that later by checking the PID file and by pinging
                        # it.
                        return
                rescue Timeout::Error
                        daemonization_timed_out
                        
                        # If the daemon doesn't fork into the background
                        # in time, then kill it.
                        begin
                                Process.kill('SIGTERM', pid)
                        rescue SystemCallError
                        end
                        begin
                                Timeout.timeout(5, Timeout::Error) do
                                        begin
                                                interruptable_waitpid(pid)
                                        rescue SystemCallError
                                        end
                                end
                        rescue Timeout::Error
                                begin
                                        Process.kill('SIGKILL', pid)
                                        interruptable_waitpid(pid)
                                rescue SystemCallError
                                end
                        end
                        raise DaemonizationTimeout
                end
                if $?.exitstatus != 0
                        raise StartError, File.read(tempfile_path).strip
                end
        else
                if @env && !@env.empty?
                        raise "Setting the :env option is not supported on this Ruby implementation."
                elsif @daemonize_for_me
                        raise "Setting the :daemonize_for_me option is not supported on this Ruby implementation."
                end

                cmd = "#{command} >\"#{tempfile_path}\""
                cmd << " 2>\"#{tempfile_path}\"" unless PLATFORM =~ /mswin/
                if !system(cmd)
                        raise StartError, File.read(tempfile_path).strip
                end
        end
ensure
        File.unlink(tempfile_path) rescue nil
end

run_ping_command() click to toggle source

# File lib/daemon_controller.rb, line 691
def run_ping_command
        if @ping_command.respond_to?(:call)
                begin
                        value = @ping_command.call
                        if value.respond_to?(:close)
                                value.close rescue nil
                        end
                        return value
                rescue *ALLOWED_CONNECT_EXCEPTIONS
                        return false
                end
        elsif @ping_command.is_a?(Array)
                type, *args = @ping_command
                if self.class.can_ping_unix_sockets?
                        case type
                        when :tcp
                                socket_domain = Socket::Constants::AF_INET
                                hostname, port = args
                                sockaddr = Socket.pack_sockaddr_in(port, hostname)
                        when :unix
                                socket_domain = Socket::Constants::AF_LOCAL
                                sockaddr = Socket.pack_sockaddr_un(args[0])
                        else
                                raise ArgumentError, "Unknown ping command type #{type.inspect}"
                        end
                        return ping_socket(socket_domain, sockaddr)
                else
                        case type
                        when :tcp
                                hostname, port = args
                                return ping_socket(hostname, port)
                        when :unix
                                raise "Pinging Unix domain sockets is not supported on this Ruby implementation"
                        else
                                raise ArgumentError, "Unknown ping command type #{type.inspect}"
                        end
                end
        else
                return system(@ping_command)
        end
end

safe_fork(double_fork) { || ... } click to toggle source

# File lib/daemon_controller.rb, line 813
def safe_fork(double_fork)
        pid = fork
        if pid.nil?
                begin
                        if double_fork
                                pid2 = fork
                                if pid2.nil?
                                        Process.setsid
                                        yield
                                end
                        else
                                yield
                        end
                rescue Exception => e
                        message = "*** Exception #{e.class} " <<
                                "(#{e}) (process #{$$}):\n" <<
                                "\tfrom " << e.backtrace.join("\n\tfrom ")
                        STDERR.write(e)
                        STDERR.flush
                        exit!
                ensure
                        exit!(0)
                end
        else
                if double_fork
                        Process.waitpid(pid) rescue nil
                        return pid
                else
                        return pid
                end
        end
end

save_log_file_information() click to toggle source

# File lib/daemon_controller.rb, line 539
def save_log_file_information
        @original_log_file_stat = File.stat(@log_file) rescue nil
        @current_log_file_stat = @original_log_file_stat
end

spawn_daemon() click to toggle source

# File lib/daemon_controller.rb, line 420
def spawn_daemon
        if @start_command.respond_to?(:call)
                run_command(@start_command.call)
        else
                run_command(@start_command)
        end
end

start_timed_out() click to toggle source

This method does nothing and only serves as a hook for the unit test.

# File lib/daemon_controller.rb, line 532
def start_timed_out
end

start_without_locking() click to toggle source

# File lib/daemon_controller.rb, line 347
def start_without_locking
        if daemon_is_running?
                raise AlreadyStarted, "Daemon '#{@identifier}' is already started"
        end
        save_log_file_information
        delete_pid_file
        begin
                started = false
                before_start
                Timeout.timeout(@start_timeout, Timeout::Error) do
                        done = false
                        spawn_daemon
                        record_activity
                        
                        # We wait until the PID file is available and until
                        # the daemon responds to pings, but we wait no longer
                        # than @start_timeout seconds in total (including daemon
                        # spawn time).
                        # Furthermore, if the log file hasn't changed for
                        # @log_file_activity_timeout seconds, and the PID file
                        # still isn't available or the daemon still doesn't
                        # respond to pings, then assume that the daemon has
                        # terminated with an error.
                        wait_until do
                                if log_file_has_changed?
                                        record_activity
                                elsif no_activity?(@log_file_activity_timeout)
                                        raise Timeout::Error, "Daemon seems to have exited"
                                end
                                pid_file_available?
                        end
                        wait_until(@ping_interval) do
                                if log_file_has_changed?
                                        record_activity
                                elsif no_activity?(@log_file_activity_timeout)
                                        raise Timeout::Error, "Daemon seems to have exited"
                                end
                                run_ping_command || !daemon_is_running?
                        end
                        started = run_ping_command
                end
                result = started
        rescue DaemonizationTimeout, Timeout::Error => e
                start_timed_out
                if pid_file_available?
                        kill_daemon_with_signal(true)
                end
                if e.is_a?(DaemonizationTimeout)
                        result = :daemonization_timeout
                else
                        result = :start_timeout
                end
        end
        if !result
                raise(StartError, differences_in_log_file ||
                        "Daemon '#{@identifier}' failed to start.")
        elsif result == :daemonization_timeout
                raise(StartTimeout, differences_in_log_file ||
                        "Daemon '#{@identifier}' didn't daemonize in time.")
        elsif result == :start_timeout
                raise(StartTimeout, differences_in_log_file ||
                        "Daemon '#{@identifier}' failed to start in time.")
        else
                return true
        end
end

wait_until(sleep_interval = 0.1) click to toggle source

# File lib/daemon_controller.rb, line 498
def wait_until(sleep_interval = 0.1)
        while !yield
                sleep(sleep_interval)
        end
end

wait_until_daemon_responds_to_ping_or_has_exited_or_log_file_has_changed() click to toggle source

# File lib/daemon_controller.rb, line 511
def wait_until_daemon_responds_to_ping_or_has_exited_or_log_file_has_changed
        while !(run_ping_command || !daemon_is_running? || log_file_has_changed?)
                sleep(@ping_interval)
        end
        return run_ping_command
end

wait_until_pid_file_is_available_or_log_file_has_changed() click to toggle source

# File lib/daemon_controller.rb, line 504
def wait_until_pid_file_is_available_or_log_file_has_changed
        while !(pid_file_available? || log_file_has_changed?)
                sleep 0.1
        end
        return pid_file_is_available?
end