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in_forward: Fixed a problem where connections are not closed on fluentd's shutdown. #861

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in_forward: Fixed a problem where connections are not closed on fluentd's shutdown. #861

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7 changes: 6 additions & 1 deletion lib/fluent/plugin/in_forward.rb
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Original file line number Diff line number Diff line change
Expand Up @@ -57,6 +57,7 @@ def start

@lsock = listen
@loop.attach(@lsock)
@connections = []

@usock = SocketUtil.create_udp_socket(@bind)
@usock.bind(@bind, @port)
Expand All @@ -82,11 +83,15 @@ def shutdown
@usock.close
@thread.join
@lsock.close
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By the way, I have another question about #shutdown. Should watchers be detached after {@usock,@lsock}.close in #shutdown? Otherwise, requests sent from clients between @loop.watchers.each { |w| w.detach if w.attached? } and @lsock.close would be lost.

@connections.each { |c| c.close }
end

def listen
log.info "listening fluent socket on #{@bind}:#{@port}"
s = Coolio::TCPServer.new(@bind, @port, Handler, @linger_timeout, log, method(:on_message))
s = Coolio::TCPServer.new(@bind, @port, Handler, @linger_timeout, log, method(:on_message)) do |connection|
@connections.reject! { |conn| conn.closed? }
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Should this block guard using Mutex?

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I think it doesn't need to be guarded.
(I would like to confirm just in case; does this block mean do |connection| ... end, not { |conn| conn.closed? }, right?)

@connections is used for closing accepted connections at shutdown, so already closed connections don't need to be included in. I think it is safe that several processes or threads come in this block at the same time.

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It looks needed for me too to guard @connections.reject! using Mutex.
I mean that:

@mutex.synchronize do
  @connections.reject!{ |conn| conn.closed? }
  @connections << connection
end

Connection callback may run twice immediately if many connection arrived at a time.

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Thank you for your comments.

Surely, I think I should guard it by mutex, but please let me ask you a question.
Can this callback be run simultaneously by threads?
It seems that only one thread(@thread) handles waiting connections, communicating with accepted connections and replying heartbeat request. So only one thread can run this callback at a time, cannot it?

@connections << connection
end
s.listen(@backlog) unless @backlog.nil?
s
end
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