[nsd-users] nsd utilize 100% cpu

[Dan Durrer]

We were also playing around with NSD.  Loading about 80,000 domains.   
Using an older machine.  Dual Xenon, 2GB ram.  One thread would be at  
100% cpu for hours,  sometimes it would never get out of that state.   
Memory usage wasn't very high.

Dan Durrer
No-IP.com

Quoting Michael Tokarev <mjt at tls.msk.ru>:

> Vadim wrote:
>> Hi there.
>>
>> Can anybody help me or explain what happen?
>>
>> I run nsd with 40к domain zones.
>> And very often nsd utilize 100%cpu for a long time.
>> For example, when I run nsdc patch, command have already finished   
>> but process nsd still running and use 100% cpu.
>
> Can you please specify at least version of nsd you're running?
>
>> When I do strace I see:
>> gettimeofday({1260459192, 450604}, NULL) = 0
>> pselect6(8, [7], [7], [], {4, 549396000}, {NULL, 8}) = 1 (out [7],   
>> left {4, 549396000})
>> write(7, "\10\0\0\0\0\17\1\t\3\10\5\0\4nw-r\2ru\0", 21) = 21
>> gettimeofday({1260459192, 461029}, NULL) = 0
>> pselect6(8, [7], [7], [], {4, 538971000}, {NULL, 8}) = 1 (out [7],   
>> left {4, 538971000})
>> write(7, "\10\0\0\0\0\26\1\20\3\17\f\0\vnw-normativ\2ru\0", 28) = 28
>> gettimeofday({1260459192, 471457}, NULL) = 0
>
> mchost? :)
>
> And what is the fd#7?  Is it the database file?  What does lsof say?
> How large the resulting db file is?
>
> Apparently nsd writes each domain label separately, without any attempt
> to batch writes.  It's much better than writing by single char as some
> other programs are doing but worse still than batching writes in at least
> 512byte blocks like stdio is doing.
>
>> And even after 20 minutes after "nsd patch" have finished, nsd   
>> process still use 100% cpu.
>
> How long it takes total?
>
> /mjt
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