[hibernate-issues] [Hibernate-JIRA] Created: (HHH-5232) Use intern() to reuse strings and reduce memory usage / save 6%

[Yves Galante (JIRA)]

Use intern() to reuse strings and reduce memory usage / save 6% 
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                 Key: HHH-5232
                 URL: http://opensource.atlassian.com/projects/hibernate/browse/HHH-5232
             Project: Hibernate Core
          Issue Type: Patch
          Components: core
    Affects Versions: 3.6
         Environment: Hibernate 3.6.0-SNAPSHOT
Linux x86_64 Bits

            Reporter: Yves Galante
            Priority: Minor
         Attachments: DuplicateString.patch

This patch is an update of JIRRA HHH-3924 for Hibernate 3.6.
Testsuite executed without new failures.

Resume of the original JIRRA HHH-3924 :

>>DefaultEntityAliases suffix and rowIdAliases String fields are not interned as are other fields in the class. This leads to significant >>of memory usage on our application.
>>BasicLoader suffixes and QueryLoader sqlAliasSuffixes can also be interned so as to save more memory

See the detailed result of this patch :

========================================
Test conditions 
========================================
Hibernate version : 3.6.0-SNAPSHOT
Yourkit           : 8.0
OS                : Linux x86_64 Bits.
Test case         : org.hibernate.test.legacy.ParentChildTest.testReplicate()
Time              : Memory snapshot is taken at the of the test.

========================================
Result before patch 
========================================
SessionFactoryImpl size : 3939 KB

Duplicates String example :

"0_"       : 452 duplicates (32KB)
"rowid_0_" : 405 duplicates (32KB)
"1_"       : 145 duplicates (10KB)
"rowid_1_" : 130 duplicates (10KB)
...

"fee3_"    :  65 duplicates (5KB)
"glarch1_" :  55 duplicates (5KB)
...

"foo2_2_5" :  46 duplicates (3KB)
...
"string"   :  28 duplicates (2KB)

========================================
Result after patch 
========================================
SessionFactoryImpl size  : 3688 KB 
Save 251 Kb, 6% of the session factory size.


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