$ 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-cygwin-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 kit.

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 Page.

##</code><code>##

$ 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 x86_64 cygwin '
    config_args='-des -Dprefix=/usr -Dmksymlinks -Darchname=x86_64-cygwin-threads -Dlibperl=cygperl5_26.dll -Dcc=gcc -Dld=g++ -Accflags=-ggdb -O2 -pipe -Wall -Werror=format-security -D_FORTIFY_SOURCE=2 -fstack-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 -fdebug-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 -fstack-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 -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 -fstack-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 -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-symbols -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