[OGNL-181] OgnlRuntime.getCompiler and thread-safety.

• Type: Bug
• Status: Open
• Priority: Minor
• Resolution: Unresolved
• Fix Version/s: 4.0.x
• Labels: concurrency thread-safety
• Assignee: Unassigned
• Reporter: Maurizio Cucchiara
• Created: 29/Oct/11 06:18
• Updated: 31/Dec/13 13:30

Description

As you can see, getCompiler is not thread safe.
I recently added a new performance benchmark to test its 3d-safety and performance: during my tests I have experienced a fast execution on unsafe version vs the safe one (though every concurrent test instantiated a new compiler).
I have not yet investigated and I still don't know what can cause running more than one instance of the compiler in the same jvm. If necessary we can consider to make compiler a singleton in order to enforce this concept.

What do you think guys?

public static OgnlExpressionCompiler getCompiler( OgnlContext ognlContext )                     
{                                                                                               
    if ( _compiler == null )                                                                    
    {                                                                                           
        try                                                                                     
        {                                                                                       
            OgnlRuntime.classForName( ognlContext, "javassist.ClassPool" );                     
            _compiler = new ExpressionCompiler();                                               
        }                                                                                       
        catch ( ClassNotFoundException e )                                                      
        {                                                                                       
            throw new IllegalArgumentException(                                                 
                "Javassist library is missing in classpath! Please add missed dependency!", e );
        }                                                                                       
    }                                                                                           
    return _compiler;                                                                           
}