Caldarale, Charles R wrote:
From: Christopher Schultz [mailto:ch...@christopherschultz.net]
Subject: Re: Disable class monitoring for reloading container classes
The timestamp of the file should be /the/ timestamp for the
file, and shouldn't be affected by the current DST settings.
The timestamp for the file itself might be affected by the
current DST setting when you /touch/ it, but not when you do
a simple stat() call.
My guess is that the problem is specific to the platform: either the JVM or the
OS is adjusting the retrieved time stamp, making it relative to the current
offset from UTC. Even though this particular OS is not widely used as a Java
EE platform (compared to the number of Linux and Windows boxes out there), I'm
a bit surprised the issue hasn't been reported elsewhere.
Try using simple Java and C programs to check the File.lastModified() and
stat() st_mtime values respectively, comparing the results both before and
after the DST switch. That should determine if the problem is in the OS, the
JVM, or Tomcat.
Jane,
Below is a simple perl program that will show the "last modified" time of a file, in 3
flavors :
- the original timestamp as a binary value (number of non-leap seconds since the "epoch",
on most systems this is 00:00:00 UTC, January 1, 1970).
- the same timestamp as GMT date/time (this is Greenwich time, non DST-adjusted)
- the same time stamp as "local" time (DST-adjusted)
Copy and paste this into a text file, save it as "showmodified.pl", then type
perl showmodified.pl <file_path>
What would be interesting would be to run the program on your two different servers, to
see if they answer differently.
This does not use the Java JVM in any way. It uses perl, which itself uses mostly the
built-in C library of the OS.
So it will tell you what the OS responds for the file timestamps.
Someone here might be able to provide a quick Java equivalent, to see if the JVM thinks
differently on the same system.
Note : I also send the program as an attachment. The list will probably strip it, so I
emailed a copy to you directly.
#!/usr/bin/perl
# showmodified.pl
use warnings;
use strict;
my ($sec,$min,$hour,$mday,$mon,$year);
my $subject = $ARGV[0] or die "missing argument";
die "File not found or not readable : $!" unless ((-f $subject) && (-r
$subject));
my $now = time();
($sec,$min,$hour,$mday,$mon,$year) = gmtime($now);
$year +=1900; $mon +=1;
print "Current GMT time (no DST) :
",sprintf("%04d/%02d/%02d-%02d:%02d:%02d",$year,$mon,$mday,$hour,$min,$sec),"\n";
($sec,$min,$hour,$mday,$mon,$year) = localtime($now);
$year +=1900; $mon +=1;
print "Current local time (with DST) :
",sprintf("%04d/%02d/%02d-%02d:%02d:%02d",$year,$mon,$mday,$hour,$min,$sec),"\n";
print "File [$subject]:\n";
my ($dev,$ino,$mode,$nlink,$uid,$gid,$rdev,$size,
$atime,$mtime,$ctime,$blksize,$blocks)
= stat($subject);
print "last modified timestamp : $mtime\n";
print "the file was last modified ",$now-$mtime," seconds ago\n";
($sec,$min,$hour,$mday,$mon,$year) = gmtime($mtime);
$year +=1900; $mon +=1;
print "last modified as GMT time (no DST) :
",sprintf("%04d/%02d/%02d-%02d:%02d:%02d",$year,$mon,$mday,$hour,$min,$sec),"\n";
($sec,$min,$hour,$mday,$mon,$year) = localtime($mtime);
$year +=1900; $mon +=1;
print "last modified as local time (with DST) :
",sprintf("%04d/%02d/%02d-%02d:%02d:%02d",$year,$mon,$mday,$hour,$min,$sec),"\n";
exit;
#!/usr/bin/perl
# showmodified.pl
use warnings;
use strict;
my ($sec,$min,$hour,$mday,$mon,$year);
my $subject = $ARGV[0] or die "missing argument";
die "File not found or not readable : $!" unless ((-f $subject) && (-r $subject));
my $now = time();
($sec,$min,$hour,$mday,$mon,$year) = gmtime($now);
$year +=1900; $mon +=1;
print "Current GMT time (no DST) : ",sprintf("%04d/%02d/%02d-%02d:%02d:%02d",$year,$mon,$mday,$hour,$min,$sec),"\n";
($sec,$min,$hour,$mday,$mon,$year) = localtime($now);
$year +=1900; $mon +=1;
print "Current local time (with DST) : ",sprintf("%04d/%02d/%02d-%02d:%02d:%02d",$year,$mon,$mday,$hour,$min,$sec),"\n";
print "File [$subject]:\n";
my ($dev,$ino,$mode,$nlink,$uid,$gid,$rdev,$size,
$atime,$mtime,$ctime,$blksize,$blocks)
= stat($subject);
print "last modified timestamp : $mtime\n";
print "the file was last modified ",$now-$mtime," seconds ago\n";
($sec,$min,$hour,$mday,$mon,$year) = gmtime($mtime);
$year +=1900; $mon +=1;
print "last modified as GMT time (no DST) : ",sprintf("%04d/%02d/%02d-%02d:%02d:%02d",$year,$mon,$mday,$hour,$min,$sec),"\n";
($sec,$min,$hour,$mday,$mon,$year) = localtime($mtime);
$year +=1900; $mon +=1;
print "last modified as local time (with DST) : ",sprintf("%04d/%02d/%02d-%02d:%02d:%02d",$year,$mon,$mday,$hour,$min,$sec),"\n";
exit;
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