#vulnerable code 
                                @Override
    public Object invoke(ServiceTaskState serviceTaskState, Object... input) {

        ServiceTaskStateImpl state = (ServiceTaskStateImpl) serviceTaskState;

        Object bean = applicationContext.getBean(state.getServiceName());

        Method method = state.getMethod();
        if (method == null) {
            synchronized (state) {
                method = state.getMethod();
                if (method == null) {
                    method = findMethod(bean.getClass(), state.getServiceMethod(), state.getParameterTypes());
                    if (method != null) {
                        state.setMethod(method);
                    }
                }
            }
        }

        if (method == null) {
            throw new EngineExecutionException("No such method[" + state.getServiceMethod() + "] on BeanClass[" + bean.getClass() + "]", FrameworkErrorCode.NoSuchMethod);
        }

        Object[] args = new Object[method.getParameterCount()];
        try {
            Class[] paramTypes = method.getParameterTypes();
            if (input != null && input.length > 0) {
                int len = input.length < paramTypes.length ? input.length : paramTypes.length;
                for (int i = 0; i < len; i++) {
                    args[i] = toJavaObject(input[i], paramTypes[i]);
                }
            }
        } catch (Exception e) {
            throw new EngineExecutionException(e, "Input to java object error, Method[" + state.getServiceMethod() + "] on BeanClass[" + bean.getClass() + "]", FrameworkErrorCode.InvalidParameter);
        }

        return invokeMethod(bean, method, args);
    } 
                            #location 8 
                            #vulnerability type THREAD_SAFETY_VIOLATION
#fixed code
                                @Override
    public Object invoke(ServiceTaskState serviceTaskState, Object... input) {
        ServiceTaskStateImpl state = (ServiceTaskStateImpl) serviceTaskState;
        if(state.isAsync()){
            if(threadPoolExecutor == null){
                if(LOGGER.isWarnEnabled()){
                    LOGGER.warn("threadPoolExecutor is null, Service[{}.{}] cannot execute asynchronously, executing synchronously now. stateName: {}", state.getServiceName(), state.getServiceMethod(), state.getName());
                }
                return doInvoke(state, input);
            }

            if(LOGGER.isInfoEnabled()){
                LOGGER.info("Submit Service[{}.{}] to asynchronously executing. stateName: {}", state.getServiceName(), state.getServiceMethod(), state.getName());
            }
            threadPoolExecutor.execute(new Runnable() {
                @Override
                public void run() {
                    doInvoke(state, input);
                }
            });
            return null;
        }
        else{
            return doInvoke(state, input);
        }
    }