1 # -*- encoding: binary -*-
4 require 'unicorn/socket_helper'
7 # Unicorn module containing all of the classes (include C extensions) for running
8 # a Unicorn web server. It contains a minimalist HTTP server with just enough
9 # functionality to service web application requests fast as possible.
12 # raised inside TeeInput when a client closes the socket inside the
13 # application dispatch. This is always raised with an empty backtrace
14 # since there is nothing in the application stack that is responsible
15 # for client shutdowns/disconnects.
16 class ClientShutdown < EOFError
19 autoload :Const, 'unicorn/const'
20 autoload :HttpRequest, 'unicorn/http_request'
21 autoload :HttpResponse, 'unicorn/http_response'
22 autoload :Configurator, 'unicorn/configurator'
23 autoload :TeeInput, 'unicorn/tee_input'
24 autoload :Util, 'unicorn/util'
27 def run(app, options = {})
28 HttpServer.new(app, options).start.join
32 # This is the process manager of Unicorn. This manages worker
33 # processes which in turn handle the I/O and application process.
34 # Listener sockets are started in the master process and shared with
35 # forked worker children.
37 class HttpServer < Struct.new(:listener_opts, :timeout, :worker_processes,
38 :before_fork, :after_fork, :before_exec,
39 :logger, :pid, :app, :preload_app,
40 :reexec_pid, :orig_app, :init_listeners,
41 :master_pid, :config, :ready_pipe)
42 include ::Unicorn::SocketHelper
44 # prevents IO objects in here from being GC-ed
47 # all bound listener sockets
50 # This hash maps PIDs to Workers
53 # We use SELF_PIPE differently in the master and worker processes:
55 # * The master process never closes or reinitializes this once
56 # initialized. Signal handlers in the master process will write to
57 # it to wake up the master from IO.select in exactly the same manner
58 # djb describes in http://cr.yp.to/docs/selfpipe.html
60 # * The workers immediately close the pipe they inherit from the
61 # master and replace it with a new pipe after forking. This new
62 # pipe is also used to wakeup from IO.select from inside (worker)
63 # signal handlers. However, workers *close* the pipe descriptors in
64 # the signal handlers to raise EBADF in IO.select instead of writing
65 # like we do in the master. We cannot easily use the reader set for
66 # IO.select because LISTENERS is already that set, and it's extra
67 # work (and cycles) to distinguish the pipe FD from the reader set
68 # once IO.select returns. So we're lazy and just close the pipe when
69 # a (rare) signal arrives in the worker and reinitialize the pipe later.
72 # signal queue used for self-piping
75 # constant lookups are faster and we're single-threaded/non-reentrant
76 REQUEST = HttpRequest.new
78 # We populate this at startup so we can figure out how to reexecute
79 # and upgrade the currently running instance of Unicorn
80 # This Hash is considered a stable interface and changing its contents
81 # will allow you to switch between different installations of Unicorn
82 # or even different installations of the same applications without
83 # downtime. Keys of this constant Hash are described as follows:
85 # * 0 - the path to the unicorn/unicorn_rails executable
86 # * :argv - a deep copy of the ARGV array the executable originally saw
87 # * :cwd - the working directory of the application, this is where
88 # you originally started Unicorn.
90 # The following example may be used in your Unicorn config file to
91 # change your working directory during a config reload (HUP) without
92 # upgrading or restarting:
94 # Dir.chdir(Unicorn::HttpServer::START_CTX[:cwd] = path)
96 # To change your unicorn executable to a different path without downtime,
97 # you can set the following in your Unicorn config file, HUP and then
98 # continue with the traditional USR2 + QUIT upgrade steps:
100 # Unicorn::HttpServer::START_CTX[0] = "/home/bofh/1.9.2/bin/unicorn"
102 :argv => ARGV.map { |arg| arg.dup },
104 # favor ENV['PWD'] since it is (usually) symlink aware for
105 # Capistrano and like systems
107 a = File.stat(pwd = ENV['PWD'])
108 b = File.stat(Dir.pwd)
109 a.ino == b.ino && a.dev == b.dev ? pwd : Dir.pwd
117 # This class and its members can be considered a stable interface
118 # and will not change in a backwards-incompatible fashion between
119 # releases of Unicorn. You may need to access it in the
120 # before_fork/after_fork hooks. See the Unicorn::Configurator RDoc
122 class Worker < Struct.new(:nr, :tmp)
126 # worker objects may be compared to just plain numbers
131 # Changes the worker process to the specified +user+ and +group+
132 # This is only intended to be called from within the worker
133 # process from the +after_fork+ hook. This should be called in
134 # the +after_fork+ hook after any priviledged functions need to be
135 # run (e.g. to set per-worker CPU affinity, niceness, etc)
137 # Any and all errors raised within this method will be propagated
138 # directly back to the caller (usually the +after_fork+ hook.
139 # These errors commonly include ArgumentError for specifying an
140 # invalid user/group and Errno::EPERM for insufficient priviledges
141 def user(user, group = nil)
142 # we do not protect the caller, checking Process.euid == 0 is
143 # insufficient because modern systems have fine-grained
144 # capabilities. Let the caller handle any and all errors.
145 uid = Etc.getpwnam(user).uid
146 gid = Etc.getgrnam(group).gid if group
147 Unicorn::Util.chown_logs(uid, gid)
149 if gid && Process.egid != gid
150 Process.initgroups(user, gid)
151 Process::GID.change_privilege(gid)
153 Process.euid != uid and Process::UID.change_privilege(uid)
158 # Creates a working server on host:port (strange things happen if
159 # port isn't a Number). Use HttpServer::run to start the server and
160 # HttpServer.run.join to join the thread that's processing
161 # incoming requests on the socket.
162 def initialize(app, options = {})
165 self.ready_pipe = options.delete(:ready_pipe)
166 self.init_listeners = options[:listeners] ? options[:listeners].dup : []
167 self.config = Configurator.new(options.merge(:use_defaults => true))
168 self.listener_opts = {}
170 # we try inheriting listeners first, so we bind them later.
171 # we don't write the pid file until we've bound listeners in case
172 # unicorn was started twice by mistake. Even though our #pid= method
173 # checks for stale/existing pid files, race conditions are still
174 # possible (and difficult/non-portable to avoid) and can be likely
175 # to clobber the pid if the second start was in quick succession
176 # after the first, so we rely on the listener binding to fail in
177 # that case. Some tests (in and outside of this source tree) and
178 # monitoring tools may also rely on pid files existing before we
179 # attempt to connect to the listener(s)
180 config.commit!(self, :skip => [:listeners, :pid])
184 # Runs the thing. Returns self so you can run join on it
186 BasicSocket.do_not_reverse_lookup = true
188 # inherit sockets from parents, they need to be plain Socket objects
189 # before they become UNIXServer or TCPServer
190 inherited = ENV['UNICORN_FD'].to_s.split(/,/).map do |fd|
191 io = Socket.for_fd(fd.to_i)
192 set_server_sockopt(io, listener_opts[sock_name(io)])
194 logger.info "inherited addr=#{sock_name(io)} fd=#{fd}"
198 config_listeners = config[:listeners].dup
199 LISTENERS.replace(inherited)
201 # we start out with generic Socket objects that get cast to either
202 # TCPServer or UNIXServer objects; but since the Socket objects
203 # share the same OS-level file descriptor as the higher-level *Server
204 # objects; we need to prevent Socket objects from being garbage-collected
205 config_listeners -= listener_names
206 if config_listeners.empty? && LISTENERS.empty?
207 config_listeners << Unicorn::Const::DEFAULT_LISTEN
208 init_listeners << Unicorn::Const::DEFAULT_LISTEN
209 START_CTX[:argv] << "-l#{Unicorn::Const::DEFAULT_LISTEN}"
211 config_listeners.each { |addr| listen(addr) }
212 raise ArgumentError, "no listeners" if LISTENERS.empty?
214 # this pipe is used to wake us up from select(2) in #join when signals
215 # are trapped. See trap_deferred.
218 # setup signal handlers before writing pid file in case people get
219 # trigger happy and send signals as soon as the pid file exists.
220 # Note that signals don't actually get handled until the #join method
221 QUEUE_SIGS.each { |sig| trap_deferred(sig) }
222 trap(:CHLD) { |_| awaken_master }
223 self.pid = config[:pid]
226 build_app! if preload_app
227 maintain_worker_count
231 # replaces current listener set with +listeners+. This will
232 # close the socket if it will not exist in the new listener set
233 def listeners=(listeners)
234 cur_names, dead_names = [], []
235 listener_names.each do |name|
237 # mark unlinked sockets as dead so we can rebind them
238 (File.socket?(name) ? cur_names : dead_names) << name
243 set_names = listener_names(listeners)
244 dead_names.concat(cur_names - set_names).uniq!
246 LISTENERS.delete_if do |io|
247 if dead_names.include?(sock_name(io))
248 IO_PURGATORY.delete_if do |pio|
249 pio.fileno == io.fileno && (pio.close rescue nil).nil? # true
251 (io.close rescue nil).nil? # true
253 set_server_sockopt(io, listener_opts[sock_name(io)])
258 (set_names - cur_names).each { |addr| listen(addr) }
261 def stdout_path=(path); redirect_io($stdout, path); end
262 def stderr_path=(path); redirect_io($stderr, path); end
265 HttpRequest::DEFAULTS["rack.logger"] = super
268 # sets the path for the PID file of the master process
271 if x = valid_pid?(path)
272 return path if pid && path == pid && x == $$
273 raise ArgumentError, "Already running on PID:#{x} " \
274 "(or pid=#{path} is stale)"
277 unlink_pid_safe(pid) if pid
281 tmp = "#{File.dirname(path)}/#{rand}.#$$"
282 File.open(tmp, File::RDWR|File::CREAT|File::EXCL, 0644)
287 File.rename(fp.path, path)
293 # add a given address to the +listeners+ set, idempotently
294 # Allows workers to add a private, per-process listener via the
295 # after_fork hook. Very useful for debugging and testing.
296 # +:tries+ may be specified as an option for the number of times
297 # to retry, and +:delay+ may be specified as the time in seconds
298 # to delay between retries.
299 # A negative value for +:tries+ indicates the listen will be
300 # retried indefinitely, this is useful when workers belonging to
301 # different masters are spawned during a transparent upgrade.
302 def listen(address, opt = {}.merge(listener_opts[address] || {}))
303 address = config.expand_addr(address)
304 return if String === address && listener_names.include?(address)
306 delay = opt[:delay] || 0.5
307 tries = opt[:tries] || 5
309 io = bind_listen(address, opt)
310 unless TCPServer === io || UNIXServer === io
314 logger.info "listening on addr=#{sock_name(io)} fd=#{io.fileno}"
317 rescue Errno::EADDRINUSE => err
318 logger.error "adding listener failed addr=#{address} (in use)"
319 raise err if tries == 0
321 logger.error "retrying in #{delay} seconds " \
322 "(#{tries < 0 ? 'infinite' : tries} tries left)"
326 logger.fatal "error adding listener addr=#{address}"
331 # monitors children and receives signals forever
332 # (or until a termination signal is sent). This handles signals
333 # one-at-a-time time and we'll happily drop signals in case somebody
334 # is signalling us too often.
337 last_check = Time.now
340 logger.info "master process ready" # test_exec.rb relies on this message
342 ready_pipe.syswrite($$.to_s)
343 ready_pipe.close rescue nil
344 self.ready_pipe = nil
351 # avoid murdering workers after our master process (or the
352 # machine) comes out of suspend/hibernation
353 if (last_check + timeout) >= (last_check = Time.now)
356 maintain_worker_count if respawn
358 when :QUIT # graceful shutdown
360 when :TERM, :INT # immediate shutdown
363 when :USR1 # rotate logs
364 logger.info "master reopening logs..."
365 Unicorn::Util.reopen_logs
366 logger.info "master done reopening logs"
367 kill_each_worker(:USR1)
368 when :USR2 # exec binary, stay alive in case something went wrong
371 if Process.ppid == 1 || Process.getpgrp != $$
373 logger.info "gracefully stopping all workers"
374 kill_each_worker(:QUIT)
376 logger.info "SIGWINCH ignored because we're not daemonized"
379 self.worker_processes += 1
381 self.worker_processes -= 1 if self.worker_processes > 0
384 if config.config_file
386 redo # immediate reaping since we may have QUIT workers
387 else # exec binary and exit if there's no config file
388 logger.info "config_file not present, reexecuting binary"
397 logger.error "Unhandled master loop exception #{e.inspect}."
398 logger.error e.backtrace.join("\n")
401 stop # gracefully shutdown all workers on our way out
402 logger.info "master complete"
403 unlink_pid_safe(pid) if pid
406 # Terminates all workers, but does not exit master process
407 def stop(graceful = true)
409 limit = Time.now + timeout
410 until WORKERS.empty? || Time.now > limit
411 kill_each_worker(graceful ? :QUIT : :TERM)
415 kill_each_worker(:KILL)
420 # list of signals we care about and trap in master.
421 QUEUE_SIGS = [ :WINCH, :QUIT, :INT, :TERM, :USR1, :USR2, :HUP,
424 # defer a signal for later processing in #join (master process)
425 def trap_deferred(signal)
426 trap(signal) do |sig_nr|
427 if SIG_QUEUE.size < 5
431 logger.error "ignoring SIG#{signal}, queue=#{SIG_QUEUE.inspect}"
436 # wait for a signal hander to wake us up and then consume the pipe
437 # Wake up every second anyways to run murder_lazy_workers
440 ready = IO.select([SELF_PIPE.first], nil, nil, 1) or return
441 ready.first && ready.first.first or return
442 loop { SELF_PIPE.first.read_nonblock(Const::CHUNK_SIZE) }
443 rescue Errno::EAGAIN, Errno::EINTR
449 SELF_PIPE.last.write_nonblock('.') # wakeup master process from select
450 rescue Errno::EAGAIN, Errno::EINTR
451 # pipe is full, master should wake up anyways
456 # reaps all unreaped workers
460 wpid, status = Process.waitpid2(-1, Process::WNOHANG)
462 if reexec_pid == wpid
463 logger.error "reaped #{status.inspect} exec()-ed"
465 self.pid = pid.chomp('.oldbin') if pid
468 worker = WORKERS.delete(wpid) and worker.tmp.close rescue nil
469 logger.info "reaped #{status.inspect} " \
470 "worker=#{worker.nr rescue 'unknown'}"
477 # reexecutes the START_CTX with a new binary
481 Process.kill(0, reexec_pid)
482 logger.error "reexec-ed child already running PID:#{reexec_pid}"
490 old_pid = "#{pid}.oldbin"
493 self.pid = old_pid # clear the path for a new pid file
495 logger.error "old PID:#{valid_pid?(old_pid)} running with " \
496 "existing pid=#{old_pid}, refusing rexec"
499 logger.error "error writing pid=#{old_pid} #{e.class} #{e.message}"
504 self.reexec_pid = fork do
505 listener_fds = LISTENERS.map { |sock| sock.fileno }
506 ENV['UNICORN_FD'] = listener_fds.join(',')
507 Dir.chdir(START_CTX[:cwd])
508 cmd = [ START_CTX[0] ].concat(START_CTX[:argv])
510 # avoid leaking FDs we don't know about, but let before_exec
511 # unset FD_CLOEXEC, if anything else in the app eventually
512 # relies on FD inheritence.
513 (3..1024).each do |io|
514 next if listener_fds.include?(io)
515 io = IO.for_fd(io) rescue nil
518 io.fcntl(Fcntl::F_SETFD, Fcntl::FD_CLOEXEC)
520 logger.info "executing #{cmd.inspect} (in #{Dir.pwd})"
521 before_exec.call(self)
524 proc_name 'master (old)'
527 # forcibly terminate all workers that haven't checked in in timeout
528 # seconds. The timeout is implemented using an unlinked File
529 # shared between the parent process and each worker. The worker
530 # runs File#chmod to modify the ctime of the File. If the ctime
531 # is stale for >timeout seconds, then we'll kill the corresponding
533 def murder_lazy_workers
534 WORKERS.dup.each_pair do |wpid, worker|
535 stat = worker.tmp.stat
536 # skip workers that disable fchmod or have never fchmod-ed
537 stat.mode == 0100600 and next
538 (diff = (Time.now - stat.ctime)) <= timeout and next
539 logger.error "worker=#{worker.nr} PID:#{wpid} timeout " \
540 "(#{diff}s > #{timeout}s), killing"
541 kill_worker(:KILL, wpid) # take no prisoners for timeout violations
545 def spawn_missing_workers
546 (0...worker_processes).each do |worker_nr|
547 WORKERS.values.include?(worker_nr) and next
548 worker = Worker.new(worker_nr, Unicorn::Util.tmpio)
549 before_fork.call(self, worker)
551 ready_pipe.close if ready_pipe
552 self.ready_pipe = nil
558 def maintain_worker_count
559 (off = WORKERS.size - worker_processes) == 0 and return
560 off < 0 and return spawn_missing_workers
561 WORKERS.dup.each_pair { |wpid,w|
562 w.nr >= worker_processes and kill_worker(:QUIT, wpid) rescue nil
566 # if we get any error, try to write something back to the client
567 # assuming we haven't closed the socket, but don't get hung up
568 # if the socket is already closed or broken. We'll always ensure
569 # the socket is closed at the end of this function
570 def handle_error(client, e)
572 when EOFError,Errno::ECONNRESET,Errno::EPIPE,Errno::EINVAL,Errno::EBADF
573 Const::ERROR_500_RESPONSE
574 when HttpParserError # try to tell the client they're bad
575 Const::ERROR_400_RESPONSE
577 logger.error "Read error: #{e.inspect}"
578 logger.error e.backtrace.join("\n")
579 Const::ERROR_500_RESPONSE
581 client.write_nonblock(msg)
587 # once a client is accepted, it is processed in its entirety here
588 # in 3 easy steps: read request, call app, write app response
589 def process_client(client)
590 client.fcntl(Fcntl::F_SETFD, Fcntl::FD_CLOEXEC)
591 response = app.call(env = REQUEST.read(client))
593 if 100 == response.first.to_i
594 client.write(Const::EXPECT_100_RESPONSE)
595 env.delete(Const::HTTP_EXPECT)
596 response = app.call(env)
598 HttpResponse.write(client, response, HttpRequest::PARSER.headers?)
600 handle_error(client, e)
603 # gets rid of stuff the worker has no business keeping track of
604 # to free some resources and drops all sig handlers.
605 # traps for USR1, USR2, and HUP may be set in the after_fork Proc
607 def init_worker_process(worker)
608 QUEUE_SIGS.each { |sig| trap(sig, nil) }
609 trap(:CHLD, 'DEFAULT')
611 proc_name "worker[#{worker.nr}]"
614 WORKERS.values.each { |other| other.tmp.close rescue nil }
616 LISTENERS.each { |sock| sock.fcntl(Fcntl::F_SETFD, Fcntl::FD_CLOEXEC) }
617 worker.tmp.fcntl(Fcntl::F_SETFD, Fcntl::FD_CLOEXEC)
618 after_fork.call(self, worker) # can drop perms
619 self.timeout /= 2.0 # halve it for select()
620 build_app! unless preload_app
623 def reopen_worker_logs(worker_nr)
624 logger.info "worker=#{worker_nr} reopening logs..."
625 Unicorn::Util.reopen_logs
626 logger.info "worker=#{worker_nr} done reopening logs"
630 # runs inside each forked worker, this sits around and waits
631 # for connections and doesn't die until the parent dies (or is
632 # given a INT, QUIT, or TERM signal)
633 def worker_loop(worker)
635 init_worker_process(worker)
636 nr = 0 # this becomes negative if we need to reopen logs
637 alive = worker.tmp # tmp is our lifeline to the master process
640 # closing anything we IO.select on will raise EBADF
641 trap(:USR1) { nr = -65536; SELF_PIPE.first.close rescue nil }
642 trap(:QUIT) { alive = nil; LISTENERS.each { |s| s.close rescue nil } }
643 [:TERM, :INT].each { |sig| trap(sig) { exit!(0) } } # instant shutdown
644 logger.info "worker=#{worker.nr} ready"
648 nr < 0 and reopen_worker_logs(worker.nr)
651 # we're a goner in timeout seconds anyways if alive.chmod
652 # breaks, so don't trap the exception. Using fchmod() since
653 # futimes() is not available in base Ruby and I very strongly
654 # prefer temporary files to be unlinked for security,
655 # performance and reliability reasons, so utime is out. No-op
656 # changes with chmod doesn't update ctime on all filesystems; so
657 # we change our counter each and every time (after process_client
658 # and before IO.select).
659 alive.chmod(m = 0 == m ? 1 : 0)
663 process_client(sock.accept_nonblock)
665 alive.chmod(m = 0 == m ? 1 : 0)
666 rescue Errno::EAGAIN, Errno::ECONNABORTED
671 # make the following bet: if we accepted clients this round,
672 # we're probably reasonably busy, so avoid calling select()
673 # and do a speculative accept_nonblock on ready listeners
674 # before we sleep again in select().
675 redo unless nr == 0 # (nr < 0) => reopen logs
677 ppid == Process.ppid or return
678 alive.chmod(m = 0 == m ? 1 : 0)
680 # timeout used so we can detect parent death:
681 ret = IO.select(LISTENERS, nil, SELF_PIPE, timeout) or redo
690 logger.error "Unhandled listen loop exception #{e.inspect}."
691 logger.error e.backtrace.join("\n")
696 # delivers a signal to a worker and fails gracefully if the worker
697 # is no longer running.
698 def kill_worker(signal, wpid)
700 Process.kill(signal, wpid)
702 worker = WORKERS.delete(wpid) and worker.tmp.close rescue nil
706 # delivers a signal to each worker
707 def kill_each_worker(signal)
708 WORKERS.keys.each { |wpid| kill_worker(signal, wpid) }
711 # unlinks a PID file at given +path+ if it contains the current PID
712 # still potentially racy without locking the directory (which is
713 # non-portable and may interact badly with other programs), but the
714 # window for hitting the race condition is small
715 def unlink_pid_safe(path)
716 (File.read(path).to_i == $$ and File.unlink(path)) rescue nil
719 # returns a PID if a given path contains a non-stale PID file,
722 wpid = File.read(path).to_i
723 wpid <= 0 and return nil
725 Process.kill(0, wpid)
728 # don't unlink stale pid files, racy without non-portable locking...
735 logger.info "reloading config_file=#{config.config_file}"
736 config[:listeners].replace(init_listeners)
739 kill_each_worker(:QUIT)
740 Unicorn::Util.reopen_logs
742 build_app! if preload_app
743 logger.info "done reloading config_file=#{config.config_file}"
745 logger.error "error reloading config_file=#{config.config_file}: " \
746 "#{e.class} #{e.message}"
750 # returns an array of string names for the given listener array
751 def listener_names(listeners = LISTENERS)
752 listeners.map { |io| sock_name(io) }
756 if app.respond_to?(:arity) && app.arity == 0
757 # exploit COW in case of preload_app. Also avoids race
758 # conditions in Rainbows! since load/require are not thread-safe
759 Unicorn.constants.each { |x| Unicorn.const_get(x) }
761 if defined?(Gem) && Gem.respond_to?(:refresh)
762 logger.info "Refreshing Gem list"
770 $0 = ([ File.basename(START_CTX[0]), tag
771 ]).concat(START_CTX[:argv]).join(' ')
774 def redirect_io(io, path)
775 File.open(path, 'ab') { |fp| io.reopen(fp) } if path
780 SELF_PIPE.each { |io| io.close rescue nil }
781 SELF_PIPE.replace(IO.pipe)
782 SELF_PIPE.each { |io| io.fcntl(Fcntl::F_SETFD, Fcntl::FD_CLOEXEC) }