Re: [bug-gawk] Does gawk deal with signal pipe correctly?

[Peng Yu]

Here is what I have. It is tested on a virtual machine (hosted on KVM
on another Ubuntu physical machine). Are you able to get the same
version vm to test?

$ cat DCt7x2zD | awk '{ print }' | head -n 1

$ echo address@hidden
0 141 0
$ cat DCt7x2zD | awk '{ print }' | head -n 1

$ echo address@hidden
0 1 0
$ cat /etc/issue
Ubuntu 14.04.5 LTS \n \l

$ uname -a
Linux caph 3.13.0-144-generic #193-Ubuntu SMP Thu Mar 15 17:03:53 UTC
2018 x86_64 GNU/Linux

I also tried on a non vm Ubuntu machine. But I don't see 0 1 0, though.

On Sun, Jun 17, 2018 at 2:06 AM,  <address@hidden> wrote:
> On a Redhat system using current code and your file I got 0 0 0 one time
> and 0 141 0 the rest of the times I tried. It appears to be a timing
> issue.
>
> The pipe(7) man page says
>
>         In Linux versions before 2.6.11, the capacity of a pipe was the same 
> as
>         the system page size (e.g., 4096 bytes on i386).  Since Linux 2.6.11,
>         the pipe capacity is 65536 bytes.
>
> Your file is a little over 18000 bytes, so it fits entirely into a
> single pipe buffer.  It looks like the 0 0 0 happens when gawk succeeds to
> read and write the data before head runs, and SIGPIPE otherwise.
>
> Unless there is a way to reproduce this consistently so that I can
> trace the code in a debugger, there's not a lot more I can do.
>
> Thanks,
>
> Arnold
>
> Peng Yu <address@hidden> wrote:
>
>> You must use the file that I provided to reproduce the problem `seq
>> 10000000` will not reveal the problem as I have shown in my original
>> post.
>>
>> I also tested on Ubuntu. Sometimes it shows 0 1 0 and sometimes it shows 0 0 
>> 0.
>>
>> $ cat DCt7x2zD | awk '{ print }' | head -n 1
>>
>> $ echo address@hidden
>> 0 1 0
>> $ awk --version | head -n 1
>> GNU Awk 4.2.0, API: 2.0 (GNU MPFR 4.0.1, GNU MP 6.1.2)
>>
>>
>> On Sat, Jun 16, 2018 at 1:51 PM,  <address@hidden> wrote:
>> > Hello.
>> >
>> > I don't think this is an awk issue.  In any case, I can't
>> > reproduce the problem:
>> >
>> >         $ gawk --version | sed 1q
>> >         GNU Awk 4.2.0, API: 2.0 (GNU MPFR 3.1.4, GNU MP 6.1.0)
>> >         [tanda:pts/2 arnold]$ for i in nawk mawk gawk
>> >         > do
>> >         > echo === $i
>> >         > seq 10000000 | $i '{ print }' | head -1
>> >         > echo address@hidden
>> >         > done
>> >         === nawk
>> >         1
>> >         141 141 0
>> >         === mawk
>> >         1
>> >         141 141 0
>> >         === gawk
>> >         1
>> >         141 141 0
>> >
>> > Arnold
>> >
>> > Peng Yu <address@hidden> wrote:
>> >
>> >> Hi,
>> >>
>> >> $ seq 10000000 | awk -e '{ print }' | head -n 1
>> >> 1
>> >> $ echo "address@hidden"
>> >> 141 141 0
>> >> $ tmpfile=$(mktemp -u)
>> >> $ seq 10000000 > "$tmpfile"
>> >> $ cat "$tmpfile" | awk -e '{ print }' | head -n 1
>> >> 1
>> >> $ echo "address@hidden"
>> >> 141 141 0
>> >>
>> >> In the following case, I see that awk sometimes return 1 instead of 0
>> >> for the input tmp2.txt (download at
>> >> https://pastebin.com/raw/DCt7x2zD). But I never see awk returns 141
>> >> for this file. Is this behavior of awk correct? Should it always
>> >> return 141?
>> >>
>> >> $ cat < tmp2.txt | awk -e '{ print }' | head -n 1
>> >>
>> >> $ echo address@hidden
>> >> 0 1 0
>> >>
>> >> --
>> >> Regards,
>> >> Peng
>>
>>
>>
>> --
>> Regards,
>> Peng



-- 
Regards,
Peng