From: Takashi Yano <takashi.yano@nifty.ne.jp>
To: cygwin-developers@cygwin.com
Subject: Re: thread safety of fhandler_base_overlapped
Date: Tue, 21 Dec 2021 09:03:03 +0900 [thread overview]
Message-ID: <20211221090303.e191372574b6a4067e996e72@nifty.ne.jp> (raw)
In-Reply-To: <20211221085813.6113e8f4e9cae4ac33ef4653@nifty.ne.jp>
On Tue, 21 Dec 2021 08:58:13 +0900
Takashi Yano wrote:
> On Mon, 20 Dec 2021 19:02:56 -0400
> David McFarland wrote:
> > I'm seeing a problem where occasionally write() returns EAGAIN on a
> > blocking pipe. I believe this happens when multiple threads are writing
> > concurrently to the pipe, and the overlapped structure is modified by
> > one thread while another one is between calls to WFMO and
> > GetOverlappedResult.
> >
> > I found this change:
> >
> > =====
> > commit 2a4b1de773e6159ea8197b6fc3f7e4845479b476
> > Author: Corinna Vinschen <corinna@vinschen.de>
> > Date: Mon Mar 23 21:06:00 2020 +0100
> >
> > Cygwin: serial: use per call OVERLAPPED structs
> >
> > Sharing the OVERLAPPED struct and event object in there between
> > read and select calls in the fhandler might have been a nice
> > optimization way back when, but it is a dangerous, not thread-safe
> > approach. Fix this by creating per-fhandler, per-call OVERLAPPED
> > structs and event objects on demand.
> >
> > Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
> > =====
> >
> > which seems to fix a similar problem in fhandler_serial.
> >
> > Is is possible that this needs to be done for fhandler_base_overlapped
> > as well? I'll try using per-call buffers to see if it fixes my problem.
>
> Pipe code was completely overhauled. Could you please try
> the latest developer snapshot?
> https://cygwin.com/snapshots/
Sorry, the new pipe code is also available in cygwin 3.3.3.
Do you have the problem in the cygwin 3.3.3?
--
Takashi Yano <takashi.yano@nifty.ne.jp>
next prev parent reply other threads:[~2021-12-21 0:03 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-12-20 23:02 David McFarland
2021-12-20 23:48 ` Ken Brown
2021-12-20 23:58 ` Takashi Yano
2021-12-21 0:03 ` Takashi Yano [this message]
2021-12-21 0:59 ` David McFarland
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