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 0a1,2line1 line2diff: 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 -- Problem reports: https://cygwin.com/problems.html FAQ: https://cygwin.com/faq/ Documentation: https://cygwin.com/docs.html Unsubscribe info: https://cygwin.com/ml/#unsubscribe-simple
