Nifi: Threads in nifi | 易学教程

问题

I want to know how threads work in nifi i mean one processor has one thread or they are in one main thread? perhaps i want to get one file from processor and then i want to update it

how can i prevent getting file data by several processor at a time except using keep file =false action?
Is it possible to use Thread.sleep inside Execute script processor code?
Is it possible to make same logic by groovy?

I tried to use java File locks but it doesn't seem to work good here is my code,

     File file = new File("C://Users//user//Desktop//try2//nifi-
      1.3.0//4//conf2.xml");
        String content = "";
        String material = "";
        BufferedReader s;
        BufferedWriter w;
        int m;
        RandomAccessFile ini = new RandomAccessFile(file, "rwd");
        FileLock lock = ini.getChannel().lock();
        DocumentBuilder dBuilder;
        Document document, doc;
        String date="";
        String data="";
        boolean make = false;
        try {

            String sCurrentLine;
            s = new BufferedReader(Channels.newReader(ini.getChannel(), "UTF-8"));
            while ((sCurrentLine = s.readLine()) != null) {
                content += sCurrentLine;
            }
            ini.seek(0);

回答1:

I want to know how threads work in nifi i mean one processor has one thread or they are in one main thread?

Nifi has a configurable pool of threads ( sandwich menu -> controller settings -> general ) and when any processor planned for execution, system takes free thread from the pool, executes processor in this thread, and returns thread to thread pool. So, each processor executes in a separate random thread.

how can i prevent getting file data by several processor at a time except using keep file =false action?

you need to store a flag file XXX processed. how you going to store it - it's your choice. for example you can create an empty file with the same name but with added extension: conf.xml -> conf.xml.done. and in code just check if file conf.xml.done exists then skip conf.xml file processing.

you can store the flag in the database, caching system, etc.