[DERBY-7049] OutOfMemoryError: Compressed class space

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Won't Fix
• Affects Version/s: 10.13.1.1
• Component/s: SQL
• Bug behavior facts: Crash, Seen in production
• Assignee: Unassigned
• Reporter: Marco
• Created: 23/Jul/19 04:15
• Updated: 12/Jan/20 20:15
• Resolved: 12/Jan/20 20:15

Description

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

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]

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:

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);
    }
}

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, but it is IMHO clearly a Derby bug.