On Sun, 1 Oct 2006, Noel J. Bergman wrote:
Stefano wrote:
Noel J. Bergman wrote:
I lowered maxcachesize to 5000 from the default of 50000
If nothing else, the smaller cache should help eliminate
that memory consumption from consideration.
Unfortunately I think that in current DNSServer implementation we
can only tune the "IN" cache and not SOA, PTR and other caches. So
they will be 50000 anyway.
I've not checked the code for this, but I'm almost sure I remember
this is how it works.
dnsjava is consistently the largest user of memory in my JAMES heap, and
does not appear to be entirely bounded, although I am having surprising
difficulty keeping it running when heap dumps are enabled.
Can you comment on the caching behavior inside of dnsjava? We use dnsjava
via:
http://svn.apache.org/repos/asf/james/server/branches/v2.3/src/java/org/apac
he/james/dnsserver/DNSServer.java
As you can see, we setup:
cache = new Cache (DClass.IN);
cache.setMaxEntries(maxCacheSize);
Lookup.setDefaultCache(cache, DClass.IN);
On a relatively slow day, my server processes 100K+ connections, of which
anywhere from 45%-70% might be blocked by a DNSRBL.
The caching algorithm in dnsjava should be fairly simple. Calling
setMaxEntries() sets the number of DNS nodes (names) in the cache; all
information about individual records with the same name is stored in one
node. The data structure is a LinkedHashMap with LRU semantics, to ensure
that only a certain number of elements are retained.
I can't think of any reason why the number of elements wouldn't be
properly bounded; the use of the LinkedHashMap is trivial and copied from
its documentation. There's a Cache.getSize() method, which should tell
you how many nodes are in use. It calls the LinkedHashMap size function
directly, so should be accurate
If you can find a way to make the size exceed the maximum size, that
would be interesting, but if the problem is that maxCacheSize nodes takes
a lot of memory, that's not really fixable without changing the way nodes
are stored.
Brian
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