Concurrency issue on the toObject function

[minhtran-q]

I have encountered a concurrent problem when using the toObject function. I spent a few hours checking the source code. And I realize a potential concurrency issue in class ToJSONObjectFunctionExtension.

JSONParser is created as a global variable in class ToJSONObjectFunctionExtension. When executing the execute(Object data, State state) function, the parse(data.toString()) function will be called with the input parameter. Everything looks good

    private static final JSONParser jsonParser = new JSONParser(JSONParser.DEFAULT_PERMISSIVE_MODE);  //global variable

    //...
    
    @Override
    protected Object execute(Object data, State state) {
        Object returnValue = null;
        try {
            returnValue = jsonParser.parse(data.toString());
        } catch (ParseException e) {
            log.error(siddhiQueryContext.getSiddhiAppContext().getName() + ":" + siddhiQueryContext.getName() +
                    ": Cannot parse the given string into JSON. Hence returning null");
        }
        return returnValue;
    }

Unfortunately, If you check function parse(String input) of class JSONParser, you will see the input parameter will be set to a global variable in class JSONParserString. In the case of multiple threads execution function execute(Object data, State state) at the same time, it will cause the concurrency issue.

Version: siddhi-execution-json 2.0.9