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From Mattias Andersson <ander...@gmail.com>
Subject OutOfMemoryError
Date Thu, 04 Jun 2015 06:39:30 GMT
We got a 'java.lang.OutOfMemoryError: Java heap space' when using a Derby
disk database with the following schema.


CREATE TABLE TEST (   ID BIGINT NOT NULL


,   NEXT _ID BIGINT

,   PREV_ ID BIGINT

,   TEST_XML XML);



ALTER TABLE TABLE

        ADD PRIMARY KEY

                (ID);


I opened the heap dump with Eclipse Memory Analyzer and found that tree
instances of org.apache.derby.impl.store.access.sort.MergeInserter occupies
290 MB of memory (that is 66 % of the total heap)


The problem seems to be that MergeInserter holds a sort buffer that
contains complete rows and the TEST_XML is about 160 kB each. MergeInserter
has an advanced algorithm to calculate the allowed size of the buffer, but
is it necessary store the complete row in the buffer, i.e. the non-indexed
values (TEST_XML is this case)?


Is there some property I can set to limit the buffer size or is it possible
to rewrite the SQL schema someway to exclude the XML type from the buffer?


Br Mattias




Following is the dominator tree from Eclipse Memory Analyzer:



org.apache.derby.impl.store.access.sort.MergeInserter @ 0xe3f72e20

|
72 |   127 533 080 |     30,76%

|- org.apache.derby.impl.store.access.sort.SortBuffer @ 0xe3f73018

|           48 |   127 532 792 |     30,76%

|  |- org.apache.derby.impl.store.access.sort.Node @ 0xe3fed5e0
|           40 |       164 384 |      0,04%

|  |  '- org.apache.derby.iapi.types.DataValueDescriptor[4] @
0xee3da280

|           32 |       164 344 |      0,04%

|  |     |- org.apache.derby.iapi.types.SQLClob @ 0xee3da2a0

|           56 |       164 240 |      0,04%

|  |     |  |- java.lang.String @ 0xee3da2d8  < ?xml
version="1.0"?...|
24 |       164 160 |      0,04%

|  |     |  |- char[1][] @ 0xee3da2f0

|           24 |            24 |      0,00%

|  |     |  '- Total: 2 entries

|              |               |

|  |     |- org.apache.derby.iapi.types.SQLLongint @ 0xee3da308
                                              |           24 |            24
|      0,00%

|  |     |- org.apache.derby.iapi.types.SQLLongint @ 0xee3da320

|           24 |            24 |      0,00%

|  |     |- org.apache.derby.iapi.types.SQLLongint @ 0xee3da338

|           24 |            24 |      0,00%

|  |     '- Total: 4 entries
                                                                     |
|               |

|  |- org.apache.derby.impl.store.access.sort.Node @ 0xe3fed608

|           40 |       164 384 |      0,04%

|  |- org.apache.derby.impl.store.access.sort.Node @ 0xe3fed630
                                                 |           40 |       164 384
|      0,04%

|  |- org.apache.derby.impl.store.access.sort.Node @ 0xe3fed658

|           40 |       164 384 |      0,04%

|  |- org.apache.derby.impl.store.access.sort.Node @ 0xe3fed680

|           40 |       164 384 |      0,04%

|  |- org.apache.derby.impl.store.access.sort.Node @ 0xe3fed6a8

 |
40 |       164 384 |      0,04%

|  |- org.apache.derby.impl.store.access.sort.Node @ 0xe3fed6d0

|           40 |       164 384 |      0,04%

|  |- org.apache.derby.impl.store.access.sort.Node @ 0xe3fed6f8
  |           40 |       164 384 |      0,04%

|  |- org.apache.derby.impl.store.access.sort.Node @ 0xe3fed720

|           40 |       164 384 |      0,04%

|  |- org.apache.derby.impl.store.access.sort.Node @ 0xe3fedd50

|           40 |       164 384 |      0,04%

|  |- org.apache.derby.impl.store.access.sort.Node @ 0xe3fedd78
                         |           40 |       164 384 |      0,04%

|  |- org.apache.derby.impl.store.access.sort.Node @ 0xe3fedda0

|           40 |       164 384 |      0,04%

|  |- org.apache.derby.impl.store.access.sort.Node @ 0xe3feddc8

|           40 |       164 384 |      0,04%

|  |- org.apache.derby.impl.store.access.sort.Node @ 0xe3fedff8
                                                |           40 |       164 384
|      0,04%

|  |- org.apache.derby.impl.store.access.sort.Node @ 0xe3fef5c8

|           40 |       164 384 |      0,04%

|  |- org.apache.derby.impl.store.access.sort.Node @ 0xe3fef5f0

|           40 |       164 384 |      0,04%

|  |- org.apache.derby.impl.store.access.sort.Node @ 0xe3fef618

|
40 |       164 384 |      0,04%

|  |- org.apache.derby.impl.store.access.sort.Node @ 0xe3ff01f8

|           40 |       164 384 |      0,04%

|  |- org.apache.derby.impl.store.access.sort.Node @ 0xe3ff04c8
 |           40 |       164 384 |      0,04%

|  |- org.apache.derby.impl.store.access.sort.Node @ 0xe3ff0608

|           40 |       164 384 |      0,04%

|  |- org.apache.derby.impl.store.access.sort.Node @ 0xe3ff0630

|           40 |       164 384 |      0,04%

|  |- org.apache.derby.impl.store.access.sort.Node @ 0xe3ff0658
                        |           40 |       164 384 |      0,04%

|  |- org.apache.derby.impl.store.access.sort.Node @ 0xe3ff0680

|           40 |       164 384 |      0,04%

|  |- org.apache.derby.impl.store.access.sort.Node @ 0xe3ff06a8

|           40 |       164 384 |      0,04%

|  |- org.apache.derby.impl.store.access.sort.Node @ 0xe3ff06d0
                                               |           40 |       164 384
|      0,04%

|  '- Total: 25 of 780 entries; 755

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