nsd users - Feb 2017 - Does NSD delay re-opening of its log file?

I've observed something strange on some of our busy servers. Logrotate
reports something like this:

/etc/cron.daily/logrotate:

gzip: stdin: file size changed while zipping

So here's what logrotate does:

1. mv nsd.log nsd.log.old

2. runs "nsd-control log_reopen"

3. gzip nsd.log.old

Occasionally, when performing step 3, gzip complains that the input file
size changed, meaning that NSD was still writing to it.

Is it possible that NSD delays re-opening of the log file?

Regards,
Anand

Hi Anand,

On 18/02/17 10:53, Anand Buddhdev wrote:
> I've observed something strange on some of our busy servers. Logrotate
> reports something like this:
> 
> /etc/cron.daily/logrotate:
> 
> gzip: stdin: file size changed while zipping
> 
> So here's what logrotate does:
> 
> 1. mv nsd.log nsd.log.old
> 
> 2. runs "nsd-control log_reopen"
> 
> 3. gzip nsd.log.old
> 
> Occasionally, when performing step 3, gzip complains that the input file
> size changed, meaning that NSD was still writing to it.
> 
> Is it possible that NSD delays re-opening of the log file?
It communicates the reopen internally over the pipes.  It could be race
condition, where the gzip starts before the reopen has finished.  sleep
1 or sleep 2 before calling gzip would solve that.

Or maybe make log_reopen wait until the reopen has finished, not sure
how to accomplish that...

Best regards, Wouter
> 
> Regards,
> Anand
> _______________________________________________
> nsd-users mailing list
> nsd-users at NLnetLabs.nl
> https://open.nlnetlabs.nl/mailman/listinfo/nsd-users
> 

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