On 08.02.10 16:42, Ronald Rudy wrote:
Kristian,
Yes, I actually do have a heap dump just like you mentioned - sorry I had
completely forgotten I retrieved one earlier (it was done so late last evening
and I am still getting my bearings this morning :))
Here is the top 17 or so from the histogram: (view the email w/ fixed width and
it should be ok)
Class Instance Count Total Size
[C 1596861 307166530
[B 10719 69009057
org.apache.derby.iapi.types.SQLVarchar 1391370 38958360
java.lang.String 1397786 22364576
[[C 1392460 16709932
[Lorg.apache.derby.iapi.types.DataValueDescriptor; 200932 8796896
org.apache.derby.impl.store.access.sort.Node 198342 5553576
org.apache.derby.iapi.types.SQLInteger 398201 1991005
org.apache.derby.impl.store.raw.data.StoredRecordHeader 93119 1583023
[Lorg.apache.derby.impl.store.access.sort.Node; 9 1049092
org.apache.derby.impl.store.raw.data.RecordId 48191 578292
[Ljava.util.concurrent.ConcurrentHashMap$HashEntry; 192 425876
[Lorg.apache.derby.impl.store.raw.data.StoredRecordHeader; 2000 404880
org.apache.derby.impl.store.raw.data.StoredPage 2000 352000
[Ljava.util.HashMap$Entry; 837 303432
[I 4839 286212
java.lang.Class 2584 196384
It looks like it's keeping a ton of SQLVarchar's in memory..
Thanks, Ron.
Indeed... If I wanted to get this fixed, I would have done one or both
of these:
a) Check if the same problem exist in 10.5.
b) Write a runnable repro executing the problematic query (the data
should preferably be generated by the repro), attach it to a Jira [1].
Maybe one could learn something by using jhat or similar (i.e. why is
Derby holding on to all the SQLVarchar objects), but having a repro
would help a lot... Further, it is not unlikely that many of the Strings
and the character arrays belong to the SQLVarchar objects...
Regards,
--
Kristian
[1] https://issues.apache.org/jira/browse/DERBY
-Ron
On Feb 8, 2010, at 9:48:52 AM, Kristian Waagan wrote:
Hi Ronald,
If you can easily control this process, can you run it with
-XX:+HeapDumpOnOutOfMemoryError and post a heap dump summary?
(I don't remember off the top of my head how you extract a histogram from the
binary heap dump, but I guess maybe using jmap or HeapViewer)
Are there many Derby classes in the top 10?
You might only see a bunch of arrays up there, in which case more investigation
may be required to understand what's going on.
Regards,
--
Kristian
