http://qs321.pair.com?node_id=11111874


in reply to missing second of time

Update: After finishing my coffee, I realize that it's normal behavior: it's just an artifact of adding a number slightly larger than an integer (epsilon_1) to another number slightly less than another integer (epsilon_2), where epsilon_1 happens to be greater than epsilon_2. As an example: 5.99 + 1.02 => 7.01

I gave it a few tries and was able to reproduce it:

$ perl -MTime::HiRes=time -le 'while () { $a=time; print $a, " ", $a-$
+b; $b=$a; sleep 1.01 }'
Use of uninitialized value $b in subtraction (-) at -e line 1.
1579951233.92519 1579951233.92519
1579951234.92536 1.00017690658569
1579951235.92573 1.00036287307739
1579951236.92672 1.00098919868469
1579951237.93894 1.01222395896912
1579951238.95456 1.01561999320984
1579951239.97017 1.01561403274536
1579951240.98579 1.01561689376831
1579951242.00141 1.01561808586121   !!!!
1579951243.01703 1.01561903953552

$ perl -MTime::HiRes=time -le 'print $Time::HiRes::VERSION'
1.9741

$ perl --version

This is perl 5, version 26, subversion 3 (v5.26.3) built for x86_64-cy
+gwin-threads-multi
(with 7 registered patches, see perl -V for more detail)

Copyright 1987-2018, Larry Wall

Perl may be copied only under the terms of either the Artistic License
+ or the
GNU General Public License, which may be found in the Perl 5 source ki
+t.

Complete documentation for Perl, including FAQ lists, should be found 
+on
this system using "man perl" or "perldoc perl".  If you have access to
+ the
Internet, point your browser at http://www.perl.org/, the Perl Home Pa
+ge.

[download]

Also including output of perl -V for interested parties:

$ perl -V
Summary of my perl5 (revision 5 version 26 subversion 3) configuration
+:

  Platform:
    osname=cygwin
    osvers=3.0.7(0.33853)
    archname=x86_64-cygwin-threads-multi
    uname='cygwin_nt-10.0 cygwinpro 3.0.7(0.33853) 2019-04-30 18:08 x8
+6_64 cygwin '
    config_args='-des -Dprefix=/usr -Dmksymlinks -Darchname=x86_64-cyg
+win-threads -Dlibperl=cygperl5_26.dll -Dcc=gcc -Dld=g++ -Accflags=-gg
+db -O2 -pipe -Wall -Werror=format-security -D_FORTIFY_SOURCE=2 -fstac
+k-protector-strong --param=ssp-buffer-size=4 -fdebug-prefix-map=/mnt/
+share/cygpkgs/perl/perl.x86_64/build=/usr/src/debug/perl-5.26.3-2 -fd
+ebug-prefix-map=/mnt/share/cygpkgs/perl/perl.x86_64/src/perl-5.26.3=/
+usr/src/debug/perl-5.26.3-2 -fwrapv'
    hint=recommended
    useposix=true
    d_sigaction=define
    useithreads=define
    usemultiplicity=define
    use64bitint=define
    use64bitall=define
    uselongdouble=undef
    usemymalloc=n
    default_inc_excludes_dot=define
    bincompat5005=undef
  Compiler:
    cc='gcc'
    ccflags ='-DPERL_USE_SAFE_PUTENV -U__STRICT_ANSI__ -D_GNU_SOURCE -
+ggdb -O2 -pipe -Wall -Werror=format-security -D_FORTIFY_SOURCE=2 -fst
+ack-protector-strong --param=ssp-buffer-size=4 -fdebug-prefix-map=/mn
+t/share/cygpkgs/perl/perl.x86_64/build=/usr/src/debug/perl-5.26.3-2 -
+fdebug-prefix-map=/mnt/share/cygpkgs/perl/perl.x86_64/src/perl-5.26.3
+=/usr/src/debug/perl-5.26.3-2 -fwrapv -fno-strict-aliasing'
    optimize='-O3'
    cppflags='-DPERL_USE_SAFE_PUTENV -U__STRICT_ANSI__ -D_GNU_SOURCE -
+ggdb -O2 -pipe -Wall -Werror=format-security -D_FORTIFY_SOURCE=2 -fst
+ack-protector-strong --param=ssp-buffer-size=4 -fdebug-prefix-map=/mn
+t/share/cygpkgs/perl/perl.x86_64/build=/usr/src/debug/perl-5.26.3-2 -
+fdebug-prefix-map=/mnt/share/cygpkgs/perl/perl.x86_64/src/perl-5.26.3
+=/usr/src/debug/perl-5.26.3-2 -fwrapv -fno-strict-aliasing'
    ccversion=''
    gccversion='7.4.0'
    gccosandvers=''
    intsize=4
    longsize=8
    ptrsize=8
    doublesize=8
    byteorder=12345678
    doublekind=3
    d_longlong=define
    longlongsize=8
    d_longdbl=define
    longdblsize=16
    longdblkind=3
    ivtype='long'
    ivsize=8
    nvtype='double'
    nvsize=8
    Off_t='off_t'
    lseeksize=8
    alignbytes=8
    prototype=define
  Linker and Libraries:
    ld='g++'
    ldflags =' -Wl,--enable-auto-import -Wl,--export-all-symbols -Wl,-
+-enable-auto-image-base -fstack-protector-strong'
    libpth=/usr/lib
    libs=-lpthread -lnsl -lgdbm -ldb -ldl -lcrypt -lgdbm_compat
    perllibs=-lpthread -lnsl -ldl -lcrypt
    libc=/usr/lib/libcygwin.a
    so=dll
    useshrplib=true
    libperl=cygperl5_26.dll
    gnulibc_version=''
  Dynamic Linking:
    dlsrc=dl_dlopen.xs
    dlext=dll
    d_dlsymun=undef
    ccdlflags=' '
    cccdlflags=' '
    lddlflags=' --shared  -Wl,--enable-auto-import -Wl,--export-all-sy
+mbols -Wl,--enable-auto-image-base -fstack-protector-strong'


Characteristics of this binary (from libperl):
  Compile-time options:
    HAS_TIMES
    MULTIPLICITY
    PERLIO_LAYERS
    PERL_COPY_ON_WRITE
    PERL_DONT_CREATE_GVSV
    PERL_IMPLICIT_CONTEXT
    PERL_OP_PARENT
    PERL_PRESERVE_IVUV
    PERL_USE_SAFE_PUTENV
    USE_64_BIT_ALL
    USE_64_BIT_INT
    USE_ITHREADS
    USE_LARGE_FILES
    USE_LOCALE
    USE_LOCALE_COLLATE
    USE_LOCALE_CTYPE
    USE_LOCALE_NUMERIC
    USE_LOCALE_TIME
    USE_PERLIO
    USE_PERL_ATOF
    USE_REENTRANT_API
  Locally applied patches:
    Cygwin: README
    Cygwin: use auto-image-base instead of fixed DLL base address
    Cygwin: modify hints
    Cygwin: Configure correct libsearch
    Cygwin: Configure correct libpth
    Cygwin: Win32 correct UTF8 handling
    Perl: File-Path-2.14 (fixes CVE2017-6512)
  Built under cygwin
  Compiled at Aug 24 2019 12:22:19
  %ENV:
    PERL5LIB="/Work/Perl/LIB"
    PERL5OPT="-Mstrict -Mwarnings"
  @INC:
    /Work/Perl/LIB
    /usr/local/lib/perl5/site_perl/5.26/x86_64-cygwin-threads
    /usr/local/share/perl5/site_perl/5.26
    /usr/lib/perl5/vendor_perl/5.26/x86_64-cygwin-threads
    /usr/share/perl5/vendor_perl/5.26
    /usr/lib/perl5/5.26/x86_64-cygwin-threads
    /usr/share/perl5/5.26

[download]

...roboticus

When your only tool is a hammer, all problems look like your thumb.

In Section Seekers of Perl Wisdom