bind-9.3.2 / CPU issue.

[JINMEI Tatuya / 神明達哉]

>>>>> On Fri, 11 Aug 2006 09:28:22 +0200, 
>>>>> Wesley Hof <wesley.hof at scarlet.biz> said:

> I currently run bind version 9.3.2 on a machine :

> Mem:   3108468k total
> Swap:  2097136k total
> Cpu:   dual Intel(R) Xeon(TM) CPU 2.80GHz

> I have four of these boxes running as caching nameservers for my customers. I get about 600 queries/second on each machine. After x amount of time my cpu usage peeks to 100% 
> resulting in _real_ slow responses, the problem doesn't go away from itself, I need to restart named to get this fixed. All four machines have this issue. I tried several upgrades,
> tuning config options like max-cache-size, max-ncache-ttl ... still no result. I do use an ACL to restrict users based on ip, tried to disable that to for a while, but still with no result. 

> Is there someone with the same issue ? Or some good tips ? :)

It would be helpful if you can provide some additional information
such as:

- how long it (usually) takes for BIND9 named to reach the problematic
  state
- how much of memory the named process consumes in this situation
- how long you saw the high-load usage before you gave up and killed
  the process

One common cause of this type of problem is the additional task for
periodic cache cleaning (every an hour by default).  In this case,
if you are very patient the problem will eventually go away after the
cleaning session.

Also, there are some common known optimizations to work around this
problem:

1. build named with its internal memory allocator:
   ./configure STD_CDEFINES='-DISC_MEM_USE_INTERNAL_MALLOC=1'

2. upgrade to BIND 9.4.  This version now enables the internal
   allocator by default, and automatically adjusts an amount of
   cleaning task that blocks incoming query processing:

-----------  from 9.4.0b1 CHANGES -----------
2019.	[tuning]	Reduce the amount of work performed per quantum
			when cleaning the cache. [RT #15986]
--------------------------------------------

					JINMEI, Tatuya
					Communication Platform Lab.
					Corporate R&D Center, Toshiba Corp.
					jinmei at isl.rdc.toshiba.co.jp