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net: Socket connection stuck in SYN_SENT when connection fails #2349

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gopherbot opened this issue Oct 8, 2011 · 5 comments
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net: Socket connection stuck in SYN_SENT when connection fails #2349

gopherbot opened this issue Oct 8, 2011 · 5 comments
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@gopherbot
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by chrisfarms:

I have been using http.Client with proxy connections and have noticed that a ton of
connections get stuck in SYN_SENT after a while. Eventually resulting in "too many
open files" errors which obviously causes serious problems.

To see this issue I have included a little example program [syn_stuck.go] that will open
a large number of HTTP connections via non-existant proxy, and then tell you to go check
"lsof". I've tried it on both OSX and Linux with same results.

After a bit of digging I believe the issue is with net/sock.go:56 .... when an
fd.connect() fails the socket is not closed. (patch attached). 

Running syn_stuck + lsof after the patch gives the expected result.

Attachments:

  1. syn_stuck.go (1778 bytes)
  2. syn_stuck_fix.diff (302 bytes)
@mikioh
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mikioh commented Oct 8, 2011

Comment 1:

Thank you for your investigation and patch sent.
Do you have a plan to contribute it by yourself?
<http://golang.org/doc/contribute.html>;

@gopherbot
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Comment 2 by chrisfarms:

I created a CL ... but I can't see how I could write a test for this. If someone points
me in the right direction I will... but since socket() does not return anything testable
when the issue occurs I don't see how :/

@rsc
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rsc commented Oct 11, 2011

Comment 3:

This issue was closed by revision 4b74956.

Status changed to Fixed.

@robpike
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robpike commented Dec 1, 2011

Comment 4:

Accidentally closed by typo in other CL

Status changed to Accepted.

@mikioh
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mikioh commented Dec 1, 2011

Comment 5:

This issue was already fixed by:
changeset:   9995:7d78fe7f328e
user:        Chris Farmiloe <chrisfarms@gmail.com>
date:        Tue Oct 11 12:53:16 2011 -0400
files:       src/pkg/net/sock.go
description:
net: fix socket leak in case of Dial failure

Status changed to Fixed.

@golang golang locked and limited conversation to collaborators Jun 24, 2016
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@mikioh @rsc @robpike @gopherbot