From: "Morten Kjærulff" <mortenkjarulff@gmail.com>
To: cygwin@cygwin.com
Subject: Re: name pipe problem: 1 writer, multiple concurrent readers
Date: Thu, 2 Jul 2020 19:50:06 +0200 [thread overview]
Message-ID: <CA+7cx1o2huaWH6s4cuwzyYQVuFgAJNBsi_bVWDdCzn-W-EAhUQ@mail.gmail.com> (raw)
In-Reply-To: <c05337b7-e422-2589-882a-46557e2e9ed1@cornell.edu>
>
> On 5/19/2020 11:20 AM, Morten Kjærulff wrote:
> > On Tue, May 19, 2020 at 3:55 PM Ken Brown via Cygwin <cygwin@cygwin.com> wrote:
> >>
> >> On 5/19/2020 7:26 AM, Morten Kjærulff via Cygwin wrote:
> >>> Hi,
> >>>
> >>> The following script:
> >>>
> >>> #!/bin/sh
> >>>
> >>> rm -f t.pip t.txt
> >>>
> >>> mkfifo t.pip
> >>> printf "line1\nline2\n" >t.txt
> >>>
> >>> ps
> >>>
> >>> {
> >>> while true ; do
> >>> cp t.txt t.pip
> >>> done
> >>> } &
> >>>
> >>> rm -f t.rc.*
> >>> for rc in 0 1 2 3 4 5 6 7 8 9 ; do
> >>> {
> >>> diff t.pip t.txt
> >>> echo $? >t.rc.$rc
> >>> }
> >>> done
> >>> echo result1 start
> >>> ls t.rc.* | wc -l
> >>> cat t.rc.*
> >>> echo result1 end
> >>>
> >>> rm -f t.rc.*
> >>> for rc in 0 1 2 3 4 5 6 7 8 9 ; do
> >>> {
> >>> diff t.pip t.txt
> >>> echo $? >t.rc.$rc
> >>> } & # run the readers in parallel
> >>> done
> >>> sleep 10
> >>> echo result2 start
> >>> ls t.rc.* | wc -l
> >>> cat t.rc.*
> >>> echo result2 end
> >>>
> >>> ps
> >>>
> >>> Give me output like this:
> >>>
> >>> $ ./tpip.sh
> >>> PID PPID PGID WINPID TTY UID STIME COMMAND
> >>> 1642 1600 1642 65264 cons1 1058872 13:18:58 /usr/bin/sh
> >>> 1600 1 1600 72728 cons1 1058872 13:18:33 /usr/bin/bash
> >>> 1645 1642 1642 42088 cons1 1058872 13:18:58 /usr/bin/ps
> >>> result1 start
> >>> 10
> >>> 0
> >>> 0
> >>> 0
> >>> 0
> >>> 0
> >>> 0
> >>> 0
> >>> 0
> >>> 0
> >>> 0
> >>> result1 end
> >>> 0a1,2
> >>>> line1
> >>>> line2
> >>> diff: t.pip
> >>> result2 start
> >>> 1
> >>> 2
> >>> result2 end
> >>> PID PPID PGID WINPID TTY UID STIME COMMAND
> >>> 1690 1688 1642 104032 cons1 1058872 13:19:01 /usr/bin/diff
> >>> 1681 1642 1642 95012 cons1 1058872 13:19:00 /usr/bin/sh
> >>> 1642 1600 1642 65264 cons1 1058872 13:18:58 /usr/bin/sh
> >>> 1684 1681 1642 99624 cons1 1058872 13:19:00 /usr/bin/diff
> >>> 1678 1676 1642 94532 cons1 1058872 13:19:00 /usr/bin/diff
> >>> 1688 1642 1642 88864 cons1 1058872 13:19:01 /usr/bin/sh
> >>> 1698 1642 1642 104820 cons1 1058872 13:19:11 /usr/bin/ps
> >>> 1692 1642 1642 66572 cons1 1058872 13:19:01 /usr/bin/sh
> >>> 1677 1674 1642 86692 cons1 1058872 13:19:00 /usr/bin/diff
> >>> 1646 1642 1642 30888 cons1 1058872 13:18:58 /usr/bin/sh
> >>> 1600 1 1600 72728 cons1 1058872 13:18:33 /usr/bin/bash
> >>> 1686 1685 1642 14320 cons1 1058872 13:19:01 /usr/bin/diff
> >>> 1685 1642 1642 25608 cons1 1058872 13:19:00 /usr/bin/sh
> >>> 1676 1642 1642 104212 cons1 1058872 13:19:00 /usr/bin/sh
> >>> 1689 1642 1642 98004 cons1 1058872 13:19:01 /usr/bin/sh
> >>> 1674 1642 1642 44152 cons1 1058872 13:19:00 /usr/bin/sh
> >>> 1680 1646 1642 28224 cons1 1058872 13:19:00 /usr/bin/cp
> >>> 1682 1679 1642 43612 cons1 1058872 13:19:00 /usr/bin/diff
> >>> 1694 1692 1642 67736 cons1 1058872 13:19:01 /usr/bin/diff
> >>> 1683 1642 1642 93544 cons1 1058872 13:19:00 /usr/bin/sh
> >>> 1679 1642 1642 90188 cons1 1058872 13:19:00 /usr/bin/sh
> >>> 1691 1689 1642 68560 cons1 1058872 13:19:01 /usr/bin/diff
> >>> 1687 1683 1642 83952 cons1 1058872 13:19:01 /usr/bin/diff
> >>>
> >>> $
> >>>
> >>> That is, when I run the readers in sequence, no problem, but when I
> >>> run the in parallel, they either hang or t.pip seems empty.
> >>
> >> The current cygwin release doesn't support multiple concurrent readers of a
> >> FIFO. I have recently added that support, which should appear in the next
> >> release, although there are still bugs to be fixed. See
> >>
> >> https://cygwin.com/pipermail/cygwin-patches/2020q2/010195.html
> >>
> >> Ken
> > Great!
>
> Let's keep the discussion on the mailing list
> > Then we will have a read-only file (pipe), which is the output of an
> > abitrary command, right?
>
> Yes.
>
> > Can we have multiple concurrent writers and one reader, which would
> > become a write-only file, which becomes the input of an abitrary
> > command?
>
> That already exists, although I found and fixed some bugs when I was developing
> the multiple reader support.
>
> > Anywhere I can see the plans for next release, if any?
>
> That's up to Corinna.
>
> Ken
I think we got a new release around the beginning of June, right?
You said that there were still issues (I can confirm).
If it can help, here is the output I see today of above scripts:
$ ./tp.sh
PID PPID PGID WINPID TTY UID STIME COMMAND
1766 1763 1763 136424 cons1 1058872 19:48:52 /usr/bin/ps
1708 1 1708 141992 cons1 1058872 19:42:22 /usr/bin/bash
1763 1708 1763 146792 cons1 1058872 19:48:52 /usr/bin/sh
result1 start
10
0
0
0
0
0
0
0
0
0
0
result1 end
0a1,2
> line1
> line2
0 [fifo_reader] diff 1806 C:\cygwin\bin\diff.exe: *** fatal
error - Can't update my handlers, Win32 error 87
result2 start
4
0
1
0
0
result2 end
PID PPID PGID WINPID TTY UID STIME COMMAND
1815 1763 1763 110264 cons1 1058872 19:48:56 /usr/bin/sh
1809 1807 1763 136060 cons1 1058872 19:48:56 /usr/bin/diff
1813 1767 1763 143812 cons1 1058872 19:48:56 /usr/bin/cp
1814 1811 1763 88380 cons1 1058872 19:48:56 /usr/bin/diff
1805 1802 1763 152044 cons1 1058872 19:48:56 /usr/bin/diff
1811 1763 1763 133876 cons1 1058872 19:48:56 /usr/bin/sh
1708 1 1708 141992 cons1 1058872 19:42:22 /usr/bin/bash
1767 1763 1763 121096 cons1 1058872 19:48:53 /usr/bin/sh
1806 1804 1763 148760 cons1 1058872 19:48:56 /usr/bin/diff
1810 1763 1763 4740 cons1 1058872 19:48:56 /usr/bin/sh
1807 1763 1763 121336 cons1 1058872 19:48:56 /usr/bin/sh
1804 1763 1763 120764 cons1 1058872 19:48:55 /usr/bin/sh
1802 1763 1763 108068 cons1 1058872 19:48:55 /usr/bin/sh
1821 1763 1763 72428 cons1 1058872 19:49:06 /usr/bin/ps
1816 1815 1763 115876 cons1 1058872 19:48:56 /usr/bin/diff
1812 1810 1763 96120 cons1 1058872 19:48:56 /usr/bin/diff
1763 1708 1763 146792 cons1 1058872 19:48:52 /usr/bin/sh
/Morten
next prev parent reply other threads:[~2020-07-02 17:50 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-19 11:26 Morten Kjærulff
2020-05-19 13:14 ` Ken Brown
[not found] ` <CA+7cx1pjvJOzMM3bwspdWGHowC+dSkPx+SrOH6wtyRO367hCJQ@mail.gmail.com>
2020-05-20 22:03 ` Ken Brown
2020-07-02 17:50 ` Morten Kjærulff [this message]
2020-07-03 11:09 ` Ken Brown
2020-07-16 19:26 ` Ken Brown
2020-08-07 8:06 ` Morten Kjærulff
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