From: Norton Allen <allen@huarp.harvard.edu>
To: Ken Brown <kbrown@cornell.edu>, cygwin <cygwin@cygwin.com>
Subject: Re: Unix Domain Socket Limitation?
Date: Mon, 30 Nov 2020 21:14:58 -0500 [thread overview]
Message-ID: <85c9c70f-c016-0f88-099e-5c772adbc648@huarp.harvard.edu> (raw)
In-Reply-To: <f5373cd4-1d3e-500a-a967-1c558541e720@cornell.edu>
On 11/30/2020 6:19 PM, Ken Brown wrote:
> On 11/30/2020 1:26 PM, Norton Allen wrote:
>> On 11/30/2020 1:14 PM, Ken Brown wrote:
>>> I can reproduce the hang, and it happens if I use the new AF_UNIX
>>> code also. But what I'm seeing (at least with the new code) isn't
>>> exactly what you describe.
>>>
>>> When the server's first select call returns, accept succeeds. The
>>> server then calls select a second time, and that call doesn't
>>> return. I haven't checked yet to see what's going on in the client,
>>> and I may not get to that for a while.
>>>
>> That's good news, and seems to be consistent with my theory that it
>> is some sort of race condition that might be particularly sensitive
>> to system-specific timing. I am compiling cygwin1.dll now.
>
> Hi Norton,
>
> I think there's a mistake in your test program. Shouldn't
> client_pselect() be waiting for the socket to be write-ready rather
> than read-ready? Here's a quote from the Posix page for 'connect':
>
> If the connection cannot be established immediately and O_NONBLOCK is
> set for the file descriptor for the socket, connect() shall fail and
> set errno to [EINPROGRESS], but the connection request shall not be
> aborted, and the connection shall be established asynchronously....
>
> When the connection has been established asynchronously, pselect(),
> select(), and poll() shall indicate that the file descriptor for the
> socket is ready for writing.
>
Yes, you are correct. In fact I had already fixed that bug on another
branch, then forgot to update it on this one. I also noticed another bug
in calculating width. Now I am not getting the blocking behavior but
instead getting the wrong bits set in select(). I think I'd better pick
this up in the morning when I am thinking straight!
next prev parent reply other threads:[~2020-12-01 2:14 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-25 21:47 Norton Allen
2020-11-25 22:27 ` Ken Brown
[not found] ` <4260ad1b-4ab2-fa36-fd0e-7c9644560114@huarp.harvard.edu>
2020-11-26 17:13 ` Ken Brown
2020-11-30 17:19 ` Norton Allen
2020-11-30 18:14 ` Ken Brown
2020-11-30 18:26 ` Norton Allen
2020-11-30 23:19 ` Ken Brown
2020-12-01 2:14 ` Norton Allen [this message]
2020-12-01 2:22 ` Norton Allen
2020-12-02 17:30 ` Norton Allen
2020-12-04 1:11 ` Ken Brown
2020-12-04 13:51 ` Norton Allen
2020-12-05 23:52 ` Ken Brown
2020-12-06 17:17 ` Norton Allen
2020-12-06 22:32 ` Ken Brown
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