Why Date() goes backwards

[noname]

I made a test page that just outputs about 100 date('Y-m-d H:i:s');

Occationally (say, 1 out of 30 tries) the time goes backwards by one or
two seconds. Like:

2006-11-14 07:29:16
2006-11-14 07:29:16
2006-11-14 07:29:16
2006-11-14 07:29:14
2006-11-14 07:29:14
2006-11-14 07:29:14

Or even reloading the page, the 2nd page will show an earlier time than
the first page by one or two seconds.

It's no big deal. It's just interesting. I wonder, how can this happen?

Terry

[Gordon Burditt]

>I made a test page that just outputs about 100 date('Y-m-d H:i:s');

>
Occationally (say, 1 out of 30 tries) the time goes backwards by one or
two seconds. Like:

2006-11-14 07:29:16
2006-11-14 07:29:16
2006-11-14 07:29:16
2006-11-14 07:29:14
2006-11-14 07:29:14
2006-11-14 07:29:14

Or even reloading the page, the 2nd page will show an earlier time than
the first page by one or two seconds.

It's no big deal. It's just interesting. I wonder, how can this happen?

Is the server time synchronized to anything? NTP tries to avoid large
jumps like that, but other methods (like maybe "net time" or "ntpdate")
might not.

[noname]

In article <12*************@corp.supernews.com>,
go***********@burditt.org (Gordon Burditt) wrote:

I made a test page that just outputs about 100 date('Y-m-d H:i:s');

Occationally (say, 1 out of 30 tries) the time goes backwards by one or
two seconds. Like:

2006-11-14 07:29:16
2006-11-14 07:29:16
2006-11-14 07:29:16
2006-11-14 07:29:14
2006-11-14 07:29:14
2006-11-14 07:29:14

Or even reloading the page, the 2nd page will show an earlier time than
the first page by one or two seconds.

It's no big deal. It's just interesting. I wonder, how can this happen?

Is the server time synchronized to anything? NTP tries to avoid large
jumps like that, but other methods (like maybe "net time" or "ntpdate")
might not.

I have asked my host. It's the same for time() and microtime(), and it
jumps forwards and back, like this:

This is with date() (time()) (microtime()):

2006-11-14 14:30:56 (1163543456) (1163543456.4591)
2006-11-14 14:30:56 (1163543456) (1163543456.4592)
2006-11-14 14:30:56 (1163543456) (1163543456.4593)
2006-11-14 14:30:56 (1163543458) (1163543458.0658)
2006-11-14 14:30:58 (1163543458) (1163543458.0659)
2006-11-14 14:30:58 (1163543458) (1163543458.066)
2006-11-14 14:30:58 (1163543458) (1163543458.0661)
2006-11-14 14:30:58 (1163543458) (1163543458.0662)
2006-11-14 14:30:58 (1163543458) (1163543458.0663)
2006-11-14 14:30:58 (1163543458) (1163543458.0664)
2006-11-14 14:30:58 (1163543458) (1163543458.0665)
2006-11-14 14:30:58 (1163543458) (1163543458.0666)
2006-11-14 14:30:58 (1163543456) (1163543456.4649)
2006-11-14 14:30:56 (1163543456) (1163543456.465)
2006-11-14 14:30:56 (1163543456) (1163543456.4652)
2006-11-14 14:30:56 (1163543456) (1163543456.4653)
2006-11-14 14:30:56 (1163543456) (1163543456.4654)

Those are 1.6 second jumps. It's like there are two clocks.

[frothpoker]

just a guess, Your ISP may be running clustered servers with a set of
servers handing the php engine and a separate one handling databases
and using with load balancing to switch the server handling the PHP
request and the time is coming from the server directed to handle the
request. Sometimes you will get server A and sometimes server B and
the clocks are very slightly apart. If the error is always the same
value (1.6 seconds) then I would sumise that this is almost definately
the answer.

Obiron

[Sanders Kaufman]

frothpoker wrote:

just a guess, Your ISP may be running clustered servers with a set of
servers handing the php engine and a separate one handling databases
and using with load balancing to switch the server handling the PHP
request and the time is coming from the server directed to handle the
request. Sometimes you will get server A and sometimes server B and
the clocks are very slightly apart. If the error is always the same
value (1.6 seconds) then I would sumise that this is almost definately
the answer.

Wow. I woulda said the OP was doing something
wrong... but that's a much more likely answer.

[Michael Fesser]

..oO(frothpoker)

>Sometimes you will get server A and sometimes server B

Within a single script request?

Micha