Your code as posted doesn't even compile. When I fix the code as follows, it works for me. So it must be your old version of threads, or your version of Perl, or maybe you are not showing us the real code you use.

use threads;
use strict;

   my $thr = threads->create (
      sub {
    while (1)
    {
        eval
        {
            while (1)
            {
              worker();
            }
        };
        if ($@)
        {
            print "Error: <$@>.\n";
            print "Error Occured: <$@>.\n";
            $@=();
            sleep (1);
        }
     }
}
);
sub worker
{
open FILE_OUT, "> /root/xyz" or die "Can't open file: $!";
}

$thr->join;

__END__

Name "main::FILE_OUT" used only once: possible typo at tmp.pl line 27.
Error: <Can't open file: No such file or directory at tmp.pl line 27.
>.
Error Occured: <Can't open file: No such file or directory at tmp.pl l
+ine 27.
>.
Error: <Can't open file: No such file or directory at tmp.pl line 27.
>.
Error Occured: <Can't open file: No such file or directory at tmp.pl l
+ine 27.
>.
Error: <Can't open file: No such file or directory at tmp.pl line 27.
>.
Error Occured: <Can't open file: No such file or directory at tmp.pl l
+ine 27.
>.
Terminating on signal SIGINT(2)
[download]

C:\Projekte>perl -V
Summary of my perl5 (revision 5 version 10 subversion 0) configuration
+:
  Platform:
    osname=MSWin32, osvers=5.1, archname=MSWin32-x86-multi-thread
    uname=''
    config_args='undef'
    hint=recommended, useposix=true, d_sigaction=undef
    useithreads=define, usemultiplicity=define
    useperlio=define, d_sfio=undef, uselargefiles=define, usesocks=und
+ef
    use64bitint=undef, use64bitall=undef, uselongdouble=undef
    usemymalloc=n, bincompat5005=undef
  Compiler:
    cc='gcc', ccflags =' -s -O2 -DWIN32 -DHAVE_DES_FCRYPT  -DPERL_IMPL
+ICIT_CONTEXT -DPERL_IMPLICIT_SYS -fno-strict-aliasing -DPERL_M
SVCRT_READFIX',
    optimize='-s -O2',
    cppflags='-DWIN32'
    ccversion='', gccversion='3.4.5', gccosandvers=''
    intsize=4, longsize=4, ptrsize=4, doublesize=8, byteorder=1234
    d_longlong=undef, longlongsize=8, d_longdbl=define, longdblsize=12
    ivtype='long', ivsize=4, nvtype='double', nvsize=8, Off_t='long lo
+ng', lseeksize=8
    alignbytes=8, prototype=define
  Linker and Libraries:
    ld='g++', ldflags ='-s -L"C:\strawberry\perl\lib\CORE" -L"C:\straw
+berry\c\lib"'
    libpth=C:\strawberry\c\lib
    libs= -lmsvcrt -lmoldname -lkernel32 -luser32 -lgdi32 -lwinspool -
+lcomdlg32 -ladvapi32 -lshell32 -lole32 -loleaut32 -lnetapi32 -
luuid -lws2_32 -lmpr -lwinmm -lversion -lodbc32 -lodbccp32
    perllibs= -lmsvcrt -lmoldname -lkernel32 -luser32 -lgdi32 -lwinspo
+ol -lcomdlg32 -ladvapi32 -lshell32 -lole32 -loleaut32 -lnetapi
32 -luuid -lws2_32 -lmpr -lwinmm -lversion -lodbc32 -lodbccp32
    libc=-lmsvcrt, so=dll, useshrplib=true, libperl=libperl510.a
    gnulibc_version=''
  Dynamic Linking:
    dlsrc=dl_win32.xs, dlext=dll, d_dlsymun=undef, ccdlflags=' '
    cccdlflags=' ', lddlflags='-mdll -s -L"C:\strawberry\perl\lib\CORE
+" -L"C:\strawberry\c\lib"'


Characteristics of this binary (from libperl):
  Compile-time options: MULTIPLICITY PERL_DONT_CREATE_GVSV
                        PERL_IMPLICIT_CONTEXT PERL_IMPLICIT_SYS
                        PERL_MALLOC_WRAP PL_OP_SLAB_ALLOC USE_ITHREADS
                        USE_LARGE_FILES USE_PERLIO
  Built under MSWin32
  Compiled at Aug 11 2008 04:41:33
  @INC:
    C:/strawberry/perl/lib
    C:/strawberry/perl/site/lib
    .
C:\Projekte>perl -Mthreads -e "die $threads::VERSION"
1.73 at -e line 1.
[download]

I was able to re-write and get eval to work in a sample program. Thanks.

Do you have any other suggestion on what I'm am trying to do. Is there another way but eval?

Here is the code I have:

#!/usr/bin/perl

use lib "/nss/nfx/thread_libs/lib/";
use threads;

my $thr = threads->create(
sub
{
    while (1)
    {
        eval
        {
            while (1)
            {
              print "Starting Main function again.\n";
              worker();
            }
        };
        if ($@)
        {
            print "Error Occured: <$@>.\n";
            $@=();
            sleep (5);
        }
    }
}
    );

sub worker
{
    open FILE_OUT, "> /root/xyz" or die "Can't open file: $!";
}

while (1)
{
    sleep 500;
}
[download]