On 2021-10-19 11:56, chris.hardison wrote:
On Tuesday, October 19, 2021, 12:11:42 PM EDT, Brian Inglis wrote:
On 2021-10-18 06:01, chris.hardison wrote:
On Thursday, September 30, 2021, 01:26:37 PM EDT, chris.hardison wrote:
My cygwin install looks good and things seem to work perfectly
for some time (hours or days), then a cygwin process started by a
windows process that is usually a child process of a windows
service written in perl will hang and then most all other cygwin
processes will hang or take a very long time to return. The
simplest example is a call to \cygwin\bin\ps from powershell.
That normally returns with sub-second response time. Once the
problem occurs that call to \cygwin\bin\ps will often take
several minutes to return. I've found that killing all cygwin
processes will temporarily resolve the problem. >>> I've read about redirecting
NUL to stdin when making the call to
cygwin processes from windows and that didn't seem to help.
I've tried "set-processmitigation -name \cygwin\bin\ps.exe
-disable ForceRelocateImages" with no real benefit.
I've also tried "\cygwin\bin\dash -c /bin/rebaseall" on startup
before the sshd service starts and that didn't seem to help.
Any suggestions on how to prevent this problem will be greatly
appreciated.
The problem seems to be that my cygwin processes that are always
the child or grandchild of a windows service use a console device
that is block buffered rather than character buffered. So using
mintty to start those processes forces character buffered which
solves the problem. I'm looking for cleaner way to force character
buffered IO. Here's an example of the change:
From
chomp(@output = `/cygwin/bin/ps -W`);TO
chomp(@output = `/cygwin/bin/mintty.exe -w hide /bin/dash -c
"/bin/ps -W > /tmp/${PID}.out"; sleep 1; type
/cygwin/tmp/${PID}.out; del /cygwin/tmp/${PID}.out`);
Hopefully someone can suggest a simpler solution.
Most Cygwin processes don't care about buffering, as they may be line
or character buffered from the terminal but block buffered when used
with pipe or file I/O.
Try using stdbuf(1) instead of mintty to change buffering.
You use it as a command prefix like nohup or time.
Perl may also have ways of changing I/O buffering internally.
> Thanks for the feedback. I came across stdbuf earlier today and
thought for sure that was the answer but when I showed it to my
co-worker he said he had already tied it with no luck, both with -i0 -e0
-o0 and with -oL.
> Actually, what is working is:`\\cygwin\\bin\\mintty.exe -w hide
/bin/dash -c "/bin/ps -W > /tmp/${PID}.out"`;
> chomp(@output = `type \\cygwin\\tmp\\${PID}.out && del
\\cygwin\\tmp\\${PID}.out`);
> I'm still hoping for a better solution.
You use perl and Cygwin has package perl-IO-Tty which provides perl
modules IO:Tty and IO::Pty.
You may be able to build a solution equivalent to mintty using one or
both of those modules.
--
Take care. Thanks, Brian Inglis, Calgary, Alberta, Canada
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