Re: [tor-talk] hidden service not reachable: Your system clock just jumped 121 seconds forward; assuming established circuits no longer work.

[Quan <quan@xxxxxxxxxxx>]

On 2012-11-26 22:57, Julian Yon wrote:
> On Sun, 25 Nov 2012 23:34:30 +0100
> Quan <quan@xxxxxxxxxxx> wrote:
> 
>> On 2012-11-25 16:22, Andreas Krey wrote:
>>>> p.s.: My system clock is running correctly
>>>
>>> Pretty definitely not. NB: The BIOS clock isn't the system clock
>>> of the operating system (which one?); this looks like your
>>> system clock gets alternatively set from two different sources
>>> (and to different values that are two minutes apart); or something
>>> similar.
>>>
>>> How often do you get these 'just jumped' messages?
>>
>> my clock is running correctly. but tor process was taking 100% of the
>> cpu. clock was still running correctly during this load but tor
>> somehow didn't get that.
> 
> What's your basis for “my clock is running correctly”? 

well I compared it to two other machines which are using same ntp server. n

this message occurs only if Tor is taking the whole cpu. clocks were
running same on all machines.


and as I said, that behaviour is not occuring any more. I restarted Tor
a dozen times and now is everything running ok. I added now 200
hiddenservices and restarted Tor and everything is running without any
problems.

I cannot say what caused this because there is nothing running on the
server except ssh server. and Tor process never took more than 60mb of
memory.


It's going to be
> hard for anybody to diagnose your problem with so little detail:
> information like what OS you're running, your hardware configuration,
> other things running on the machine that could be affecting performance
> are all clues to the puzzle.

debian squeeze.

> 
> One clue though is that you say Tor was at 100%. Assuming this is a
> Unix-like system, what's the loadavg when this happens? 

4 core machine with almost no load at all.

(Sorry, I don't
> know how to retrieve an equivalent statistic on Windows.) If it's
> greater than the number of CPU cores for any extended period you have
> then your problem may simply be that your computer isn't powerful
> enough to do what you're asking of it.

computer is powerful enough. there is almost no load at all.


> 
> Consider this scenario: Tor is working its arse off handling too many
> circuits and/or hidden services, maxing out your CPU. Of course, Tor
> isn't the only process being scheduled: there are httpd processes
> serving your hidden sites and possibly non-hidden ones, other daemons
> such as sshd, ftpd, smbd etc, and of course anything you're doing
> interactively on the console at the time. And if your CPU can't keep
> up, maybe the filesystem can't either, causing processes to get stuck
> while other processes are in IOwait. Throw in memory shortage and the
> associated heavy swapping (= more disk IO, more CPU usage, more
> scheduling delays) and you have a recipe for things spiralling out of
> control. Conceivably there could be a significant time between Tor
> being scheduled out and back in again. Multiply this by a few
> scheduling cycles, and perhaps it could indeed look to Tor as though
> the clock had jumped forwards.

that is my opinion too but I assume that this was caused only by tor.
there were no other processes running, over 2gb of free memory, machine
was not overloaded etc.


I am not able reproduce this but I let tor run with "Log info-err" to
try to find out the reason.

thanks

Quan

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