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Subject:	RE: Cygwin1.dll 1.7.1 causes ActivePerl 5.10 hang on gzip pipe close on Windows Server 2003
Date:	Mon, 22 Mar 2010 14:59:34 -0700
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From:	"Matthew Kidd" <matthew DOT kidd AT ghctechnologies DOT com>
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>> >> I upgraded to Cygwin 1.7.1 on a (64-bit) Windows Server 2003
>> >> and immediately ran into trouble. It seems that Perl can no
>> >> longer shutdown pipes related to Cygwin executables. Here is
>> >> some example code:
>> >>=20
>> >> #!/usr/bin/perl
>> >>=20
>> >> use strict;
>> >>=20
>> >> # my $fname =3D 'Y:\path\to\ratherbigfile.gz';
>> >> my $fname =3D '/cygdrive/y/path/to/ratherbigfile.gz';
>> >>=20
>> >> open(FH, "gzip -dc $fname |") || die 'open failed.';
>> >> for (1..4) { my $fline =3D <FH>; print $fline; }
>> >>=20
>> >> close(FH);
>> >> print "done\n";
>> >>=20=20
>> >>=20
>> >> Before Cygwin 1.7.1 this code ran fine. It printed out four
>> >> lines, closed the pipe, and exited. But now it hangs at the
>> >> close(FH) statement and the child gzip process maxes out a
>> >> core continuing to uncompress the big file. I either have to
>> >> kill the gzip process or the Perl process. This problem happens
>> >> whether I use a Windows style file path or a Unix style
>> >> file path. It doesn't matter if I use 32-bit or 64-bit Perl.
>> >>=20
>> >> If I replace the cygwin1.dll file from the 1.7.1 installation
>> >> with an older version of cygwin1.dll from a different installation
>> >> (specifically 1.5.25 cr-0x5f1), the code above works fine (though
>> >> I imagine mixing and matching DLL version is not a good long term
>> >> solution).
>>=20
>> > Try the latest developer snapshot from http://cygwin.com/snapshots/
>> > fixes your problem.
>>=20
>> I had no luck with the 1.7.2 cygwin1.dll from the developer snapshot.
>> Since the 1.7.1 Cygwin package does not show this problem on a 32-bit
>> Windows 7 box I think it is a 64-bit architecture issue.
>
> I have no problem running your testcase with Windows 7 64 and the
> latest Cygwin from CVS.

Did you check using a very large file? What I have learned on the 64-bit
Windows 2003 box is that the close(FH) does eventually succeed, but only
after the entire file has been uncompressed. If your test file were
small you would not necessarily observe that close(FH) does not take
place immediately after the four lines have been read.

I'll try to get my hands on a 64-bit Windows 7 box myself.


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