public void setProcessThreads(int processThreads) {
        if (processThreads < 0) {
            throw new IllegalArgumentException("Invalid processThreads value:" + processThreads);
        }
        this.processThreads = processThreads;
    }
Set the threads number for processing messages.

@param processThreads
metamorphosis-client/src/main/java/com/taobao/metamorphosis/client/extension/spring/DefaultMessageListener.java