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https://issues.apache.org/jira/browse/DERBY-7049?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16904684#comment-16904684
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Rick Hillegas commented on DERBY-7049:
--------------------------------------
Glad to hear that you have been able to push this problem forward.
The statement cache is per-database and it is shared across all sessions in
that database.
The default size of the statement cache is 100 statements. You can configure
this via the derby.language.statementCacheSize property. See
http://db.apache.org/derby/docs/10.15/ref/rrefproperstatementcachesize.html and
http://db.apache.org/derby/docs/10.15/tuning/ctundepth29804.html.
You may have some other leak. See Bryan's advice above for further advice about
that.
> OutOfMemoryError: Compressed class space
> ----------------------------------------
>
> Key: DERBY-7049
> URL: https://issues.apache.org/jira/browse/DERBY-7049
> Project: Derby
> Issue Type: Bug
> Components: SQL
> Affects Versions: 10.13.1.1
> Reporter: Marco
> Priority: Major
> Attachments: StatementLogReadingVTI.java
>
>
> After a few days of working with an embedded Derby database (currently
> version 10.13.1.1 on Oracle Java 1.8.0_201-b09), the following error occurs:
> *java.lang.OutOfMemoryError: Compressed class space*
> {code:java}
> java.lang.OutOfMemoryError: Compressed class space
> at java.lang.ClassLoader.defineClass1(Native Method) ~[na:1.8.0_201]
> at java.lang.ClassLoader.defineClass(ClassLoader.java:763) ~[na:1.8.0_201]
> at java.lang.ClassLoader.defineClass(ClassLoader.java:642) ~[na:1.8.0_201]
> at
> org.apache.derby.impl.services.reflect.ReflectLoaderJava2.loadGeneratedClass(Unknown
> Source) ~[derby-10.13.1.1.jar:na]
> at
> org.apache.derby.impl.services.reflect.ReflectClassesJava2.loadGeneratedClassFromData(Unknown
> Source) ~[derby-10.13.1.1.jar:na]
> at
> org.apache.derby.impl.services.reflect.DatabaseClasses.loadGeneratedClass(Unknown
> Source) ~[derby-10.13.1.1.jar:na]
> at
> org.apache.derby.impl.services.bytecode.GClass.getGeneratedClass(Unknown
> Source) ~[derby-10.13.1.1.jar:na]
> at
> org.apache.derby.impl.sql.compile.ExpressionClassBuilder.getGeneratedClass(Unknown
> Source) ~[derby-10.13.1.1.jar:na]
> at org.apache.derby.impl.sql.compile.StatementNode.generate(Unknown
> Source) ~[derby-10.13.1.1.jar:na]
> at org.apache.derby.impl.sql.GenericStatement.prepMinion(Unknown Source)
> ~[derby-10.13.1.1.jar:na]
> at org.apache.derby.impl.sql.GenericStatement.prepare(Unknown Source)
> ~[derby-10.13.1.1.jar:na]
> at
> org.apache.derby.impl.sql.conn.GenericLanguageConnectionContext.prepareInternalStatement(Unknown
> Source) ~[derby-10.13.1.1.jar:na]
> at org.apache.derby.impl.jdbc.EmbedPreparedStatement.<init>(Unknown
> Source) ~[derby-10.13.1.1.jar:na]
> at org.apache.derby.impl.jdbc.EmbedPreparedStatement42.<init>(Unknown
> Source) ~[derby-10.13.1.1.jar:na]
> at org.apache.derby.jdbc.Driver42.newEmbedPreparedStatement(Unknown
> Source) ~[derby-10.13.1.1.jar:na]
> at org.apache.derby.impl.jdbc.EmbedConnection.prepareStatement(Unknown
> Source) ~[derby-10.13.1.1.jar:na]
> at org.apache.derby.impl.jdbc.EmbedConnection.prepareStatement(Unknown
> Source) ~[derby-10.13.1.1.jar:na]
> at
> org.datanucleus.store.rdbms.datasource.dbcp.DelegatingConnection.prepareStatement(DelegatingConnection.java:259)
> ~[datanucleus-rdbms-4.0.12.jar:na]{code}
> I tried to solve the problem by periodically shutting down the database,
> because I read that the generated classes as well as all other allocated
> resources should be released when the DB is shut-down.
> I thus perform the following code once per roughly 20 minutes:
> {code:java}
> String shutdownConnectionURL = connectionURL + ";shutdown=true";
> try {
> DriverManager.getConnection(shutdownConnectionURL);
> } catch (SQLException e) {
> int errorCode = e.getErrorCode();
> if (DERBY_ERROR_CODE_SHUTDOWN_DATABASE_SUCCESSFULLY != errorCode &&
> DERBY_ERROR_CODE_SHUTDOWN_DATABASE_WAS_NOT_RUNNING != errorCode) {
> throw new RuntimeException(e);
> }
> }
> {code}
> Unfortunately, this has no effect :( The OutOfMemoryError still occurs after
> about 2 days. Do I assume correctly that the above code _should_ properly
> shut-down the database? And do I assume correctly that this shut-down should
> release the generated classes?
> IMHO, it is already a bug in Derby that I need to shut-down the database at
> all in order to prevent it from piling up generated classes. Shouldn't it
> already release the generated classes at the end of each transaction? But
> even if I really have to shut-down the DB, it is certainly a bug that the
> classes are still kept in "compressed class space" even after the shut-down.
> I searched the release notes and the existing bugs (here in JIRA) and did not
> find anything related to this {{OutOfMemoryError}}. Hence, I open this
> bug-report, now.
> This issue was originally reported in
> [subshare#74|https://github.com/subshare/subshare/issues/74], but it is IMHO
> clearly a Derby bug.
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