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Re: ctrl-c doesn't reliably kill ping
- From: Frank Farance <frank at farance dot com>
- To: cygwin at cygwin dot com
- Date: Thu, 17 Mar 2016 17:10:03 -0400
- Subject: Re: ctrl-c doesn't reliably kill ping
- Authentication-results: sourceware.org; auth=none
- References: <56E6F25A dot 7070000 at gmx dot de> <56E75B3E dot 7020102 at farance dot com> <54382838 dot 20160315140038 at yandex dot ru> <9ee672500661e37c240d30d8413ca0af at mail dot kylheku dot com> <56E972EB dot 9000204 at gmail dot com> <CAOC2fq80JudLuzgtg+P-jCG5ZiS0jMNqTE86Tn3ynJm3=6kFSQ at mail dot gmail dot com> <f9bfd813b9156f888a1571fb41c3ded5 at mail dot kylheku dot com> <CAD8GWsvgv8e6BmJvximDM5oOKmqR=+EKzrmQXQMNfn612egdug at mail dot gmail dot com>
Thank you for the thoughtful observations, responses, and suggestions, which I
- Suggestion #1: Try different DNS settings not using Verizon.
- Suggestion #2: Try different Verizon configuration.
- Suggestion #3: Try Windows version of ping.
- Observation #4: This shouldn't work unless I am administrator (FYI: I've
configured the cygwin terminal to run as administrator).
- Question #5: Am I running the windows ping? Answer: Nope, I did "type ping",
which returned "/usr/bin/ping".
Regarding Verizon, and possibly different settings, my point was not to identify
flaws in Verizon, I just wanted to give you background on the problem - and I
believe people understand its nature. I am well aware of well-known DNS
servers, such as 18.104.22.168 and 22.214.171.124 -- I am Old School, so I still occasionally
use the UUNET DNS caches 198.6.1.? to test stuff. :-)
Regarding incompatible ISPs, I believe the program should be robust enough to
succeed, robust enough to fail, but it shouldn't hang and become non-interruptable.
So from a POSIX compatibility and operating system kernel perspective, I am
surprised that it is possible to write an application program that gets into an
non-interruptable state. In traditional UNIX kernels, it was possible to get
stuck in a *hard* wait (like local hard drive access), but I don't understand
how this is possible with ping or any other network application.
Perhaps I don't understand the cygwin signal mechanism and someone can point me
in the right direction for ping. Perhaps someone can explain how ping can get
into this state.
Anyway, as we'd say in standardizing the C programming language, this behavior
is a "surprise" ... and we should look to eliminate "surprises".
Again, thank you in advance for your help.
Frank Farance, Farance Inc. T: +1 212 486 4700 M: +1 917 751 2900
Standards/Products/Services for Information/Communication Technologies
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