[freenet-dev] BDB uses far more memory than it's supposed to; ideas?

[Matthew Toseland]

[B [I [C [[B almost certainly mean byte[], int[], char[], byte[][].

I didn't get jmap to work (maybe because I was using java 5), but I did
do some invasive profiling (with stack traces), and used that to
identify and eliminate some high-churn objects; if the current problem is
that too much garbage collection is occurring (causing 100% cpu usage),
this is most likely caused by too many objects being allocated per second.

Anyway my original trace is here:
http://amphibian.dyndns.org/java.hprof.multi-day.no-logging.1011.txt

This is produced by options:
wrapper.java.additional.3=-Xloggc:freenet.loggc
wrapper.java.additional.4=-Xrunhprof:heap=all,format=a,depth=12,lineno=y,doe=y,
gc_okay=y

(Set logging to NORMAL if you haven't already; heavy logging with
profiling makes the node break)

On Sun, Feb 04, 2007 at 06:29:04PM +0100, Jano wrote:
> Jano wrote:
> 
> > Matthew Toseland wrote:
> 
> >> How to identify such misuse?
> > 
> > Memory profiling, I'd say. Though I have never done it with java.
> 
> I've started toying with jmap/jhat after upgrading to java6. This node is a
> linux one. Here's a heap dump at node start:
> 
> Top 12 Class histogram:
> 
> Class                                   Instance Count  Total Size
> class [B                                        379353  18473891
> class [I                                        315048  12805068
> class [C                                        56549   11786932
> class [[B                                       6137    3190228
> class [Lcom.sleepycat.je.tree.Node;             6135    3190200
> class [Ljava.util.HashMap$Entry;                33158   2950160
> class [J                                        2037    2091504
> class freenet.client.async.SingleBlockInserter  30965   1795970
> class [[I                                       20812   1415092
> class java.util.HashMap$Entry                   66778   1068448
> class java.util.HashMap                         33144   1060608
> class java.lang.String                          56831   909296
> 
> Top 10 class instance counts (excluding platform):
> 
> 31204 instances of class freenet.client.FailureCodeTracker
> 30965 instances of class freenet.client.async.SingleBlockInserter
> 20604 instances of class freenet.support.io.ReadOnlyFileSliceBucket
> 16213 instances of class com.sleepycat.je.tree.LN
> 10413 instances of class freenet.support.io.FileBucket
> 10403 instances of class freenet.crypt.ciphers.Rijndael
> 10367 instances of class freenet.support.io.PaddedEphemerallyEncryptedBucket
> 10355 instances of class freenet.support.io.DelayedFreeBucket
> 9947 instances of class freenet.keys.FreenetURI
> 6157 instances of class com.sleepycat.je.latch.Java5SharedLatchImpl 
> 
> Total instances pending finalization: 0
> 
> The strange short names are, so it seems, "platform classes", which I don't
> know what means (apparently java.* and javax.* classes, but these strange
> names go away too).
> 
> And here's the heap dump at the moment of node death (node configured with
> 128m max mem):
> 
> Class                                   Instance Count  Total Size
> class [B                                        771728  34242096
> class [C                                        113887  19922068
> class [I                                        439531  18758092
> class [[B                                       9527    4953028
> class [Lcom.sleepycat.je.tree.Node;             9525    4953000
> class [Ljava.util.HashMap$Entry;                50089   4642912
> class [J                                        3030    3111184
> class com.sleepycat.je.tree.LN                  173461  2254993
> class [[I                                       28586   1943756
> class java.lang.String                          115987  1855792
> class freenet.client.async.SingleBlockInserter  31080   1802640
> class java.util.HashMap$Entry                   108956  1743296
> 
> 173461 instances of class com.sleepycat.je.tree.LN
> 31413 instances of class freenet.client.FailureCodeTracker
> 31080 instances of class freenet.client.async.SingleBlockInserter
> 20613 instances of class freenet.support.io.ReadOnlyFileSliceBucket
> 17564 instances of class freenet.keys.FreenetURI
> 14291 instances of class freenet.crypt.ciphers.Rijndael
> 14246 instances of class freenet.support.io.PaddedEphemerallyEncryptedBucket
> 11793 instances of class freenet.support.io.FileBucket
> 10358 instances of class freenet.support.io.DelayedFreeBucket
> 10065 instances of class freenet.support.LRUQueue$QItem
> 
> Total instances pending finalization: 0
> 
> From these numbers it seems that sleepycat is notably leaking memory (the LN
> objects). Someone familiar with DBD could perhaps pinpoint seeing this if
> this is a bug in BDB or a mismanagement in freenet (unclosed whatevers?)
> 
> I'm running now with 256m to see if the differences are even more apparent.
> I'll send later some graphs obtained with jconsole that pretty much back
> that there's leaking going on (i.e. if we find the leak, freenet will run
> comfortably with 128m or less).
> 
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