#1501 [java] [apex] CyclomaticComplexity rule causes OOM when class reporting is disabled

[Frits Jalvingh]

When you set showClassesComplexity= false, running PMD on a large dataset will shows a big memory leak leading to OOM.

The cause is a bug in StdCyclomaticComplexityRule:

public Object visit(ASTClassOrInterfaceDeclaration node, Object data) {
    if ( node.isInterface() ) {
      return data;
    }

    entryStack.push( new Entry( node ) );
    super.visit( node, data );
    if ( showClassesComplexity ) {
      Entry classEntry = entryStack.pop(); // <<<<<<<< THIS IS WRONG AND MUST BE BEFORE THE IF
        if ( classEntry.getComplexityAverage() >= reportLevel
            || classEntry.highestDecisionPoints >= reportLevel ) {
          addViolation( data, node, new String[] {
              "class",
              node.getImage(),
              classEntry.getComplexityAverage() + " (Highest = "
                  + classEntry.highestDecisionPoints + ')' } );
        }
    }
    return data;
  }

The marked pop only executes with the property true; with false the stack collects and retains all entries leading to a huge retained heap for this rule.

I will try to send a pull request this weekend to fix this.

[Andreas Dangel]

See PR https://github.com/pmd/pmd/pull/103

This will be fixed with PMD 5.3.8, 5.4.3 and 5.5.1 and later (for Java)
For Apex, this will be fixed with PMD 5.5.1.