How to read a file using multithreading in java. Disk I/O doesn't parallelize well.

How to read a file using multithreading in java parse for parsing the lines to a Iterable<CSVRecord>) and then loop over them, creating my Entity class objects for each and then add these to a some kind of an Iterable for saving to To create threads, create a new class that extends the Thread class, and instantiate that class. The only things that do mutate are the queue and the flags. 3) Have the worker thread process the file. If each thread is processing one line at a time (and the order of lines don't matter), then you should probably use the producer/consumer model, where only one thread actually reads from the file and places the workload in a BlockingQueue, while other threads periodically May 5, 2022 · Right now I am using below code for reading the file - private static void readFile(List<String> paths){ for (String path : paths) { File filePath = new File(path Jun 15, 2022 · In Java, file locking involves stopping processes or threads from changing a file. file=file Jan 10, 2025 · Owing to the fact that you know what a stream is, let’s polish up File Handling in Java by further understanding the various methods that are useful for performing operations on the files like creating, reading, and writing files. Afterwards, run as many threads as you can profitably use to simply pull the next entry off of the queue and process it. Because, those threads will, in turn, keep waiting to gain a lock on the table and you end up burning more time than you do in "for loop". The file should be merged in such a way that it contains one line of first file and one line of second file. Do not store the whole data in memory, like reading all lines and keeping as string. txt")))); inputStream. txt")); you need to use something like . In your case, I'd just launch a pool of threads with as many threads as your process will allow, each with a "read the whole file" request for a file assigned to it, and let the OS decide which files to read in which order. How do I achieve the writing with multithreading? I read about synchronize method but when I apply it to the outputStream file I get failures. Files. My idea is to use the actually file name that our threads will be reading and writing to. I have text files with First name and Last name of employees. But this will lead to code that is less performant, and harder to Aug 8, 2018 · I have an alternate approach of reading file via stream and using parallel. We will cover various options how to read a file in Java efficiently using plain Java API. For information on how to read portions of a file. If you use Java 7+ you should use java. Apr 8, 2020 · read text file using threads java. Assign files equally to each thread. "In short: Handling different document-objects in different threads will work. skip(<number of bytes to start of first desired record>); Scanner read = new Scanner(inputStream); // then make sure you only read as many records as you need May 29, 2015 · I have a selenium test that reads and writes to an excel file. Here is the design which i followed to solve my problem: Use main program as master, read the whole file in one go (but dont start processing). Jan 21, 2019 · FYI: If this is an exercise, that's fine, but be aware that reading a file using multiple threads may actually degrade performance, since the disk will be the performance bottleneck. Each thread will read different pattern like 001* and 002*. Oct 24, 2023 · There’s a bunch of files with dumy data transactions on them, and we will try to process them with multithreading in Java and see the difference between with and without multithreading. Put all the files in something like a BlockingQueue or another thread-safe collection and all the executing ones can just poll() it at will. You will need to investigate how many threads to use, the number of threads you should use in application has to be related with number of cores in CPU, in that way will use full CPU. Jun 17, 2013 · The big advantage is that directory creation, unlike file creation, is atomic; as such, you can use Files. Here our target file is example. nio. Runnable task should traverse folder to find out new folders etc. parallel(). assuming your indexing system supports multiple threads, you probably want a producer/consumer setup with one thread reading the file and pushing each line into a BlockingQueue (the producer), and multiple threads pulling lines from the BlockingQueue and pushing them into the index (the consumers). In testing phase i used Scanner, with a May 5, 2018 · Use a parallel stream: objects. Read multiple files from a location and write the content of each file to the same destination file by appending each time. But I think that before using the save method, I would have to read in the lines from the CSV file (I am currently using FileReader for reading and then CSVFormat. But this will lead to code that is less performant, and harder to Feb 27, 2019 · you need to create a Class which will implement callable as below and store futures in a list and finally process the futures as below. Read files using NIO Apr 29, 2012 · public synchronized void write() { write to store; } public synchronized String read() { read from store; } This, however, (maybe) has a drawback: it also forbids two reader threads to read at the same time. Disk I/O doesn't parallelize well. Jun 24, 2017 · You would be better off not using an intermediate buffer. Now I have submitted all these tasks to these threads. Oct 31, 2019 · Never read the whole file at once. There will still be some locking under the hood since the Operating System needs to keep the filesystem consistent, but it should be better than writing to a single file with manual locking or writing to standard output (which has internal synchronization). CPU may be blocked by IO or other stuff. Mar 25, 2016 · I am quite sure about implementing the consumer but not sure if using threads to read file would be helpful. How to write java thread pool programme to read content Dec 13, 2019 · How to write Multithreaded Programs in Java. If you want to read the first line of every file, the the second of every file, etc. its Dec 9, 2017 · How can I read a file in Java using multithreading? It doesn't matter if it's slower than using once, I have to do it. In the Java world, you'd use the Executors. 4. , you need to stop when you've reached the last line of the longest file. In case each thread used an own Runnable implementation (?), this should work. This example reads text file using multiple threads. Jul 11, 2017 · I am processing files in directories. Threads can improve the performance and responsiveness of a program by allowing paral Nov 24, 2012 · In practice, I/O-bound applications can still benefit substantially from multithreading because it can be much faster to read or write a few files in parallel than sequentially. Java has many ways to read the file in chunks or line by line, like BufferedReader, Scanner, BufferedInputStream Apr 29, 2012 · public synchronized void write() { write to store; } public synchronized String read() { read from store; } This, however, (maybe) has a drawback: it also forbids two reader threads to read at the same time. Is there a way to make this process faster using threads and will Say there is another file (or a list of files) to be read then you can spin up an executor (not a single threaded) to read multiple files in parallel. and Aug 3, 2017 · This is the example of creating of how we can do using 2 threads and 2 tables. Java Multithread File Read + Operation + Write. I initially thought to read line by line. So i tried to use multiple threads. Jan 6, 2013 · It sounds like you need a configurable pool of threads, and each file-read operation is a job to be submitted into that pool. Wondering is it possible to achieve better performance, using multi-threading, for example when we find new folder we submit new Runnable in fixed ThreadPool. Read file line by line or in chunks, like reading few lines from text file or reading few bytes from binary file. If you set up a file channel in memory, you should be able to process the data in parallel from there with great speed, but chances are you won't need it as you'll see a huge speed increase. Advantage Can assign N number of threads on runtime based on CPU utilization. 50. Feb 6, 2022 · 1 Using Java API. Your bottleneck is most likely the indexing, not the file reading. Divide the file into N chunks, read each chunk in a thread, then merge them in order. java (Creates a Thread pool and adds all the tasks to the Blocking queue and submits) Oct 27, 2015 · I read a set of json files in a directory to check the name attribute and to populate a HashMap&lt;Name,List&lt;File_path&gt;&gt;. re-building a file with known offsets and sizes. Some demo code as following Sep 21, 2018 · This is a pure java response, rather than specifically a selenium response. The extending class must override the run method and call the start method to begin execution of the thread. Oct 8, 2019 · I'm trying to read a large (in GBs) file with JSON lines, do some 'processing' and write the result to another file. Sep 23, 2020 · Let's start by creating the search function itself. It is the basic idea as suggested by user slaks Jan 30, 2024 · To read a file in a separate thread, we can create a new thread and pass a Runnable object that reads the file. We can create threads in Java using the following. lets say for simplicity sake the actual code that would download the file is in downloadFile() method and fileNames is the list of filenames that match the pattern. @havexz 's approach is quite good: writing everything to the same log file and using nested diagnostic contexts. My code: Mar 16, 2016 · @trutheality I also use finals for all members which do not mutate. The queue is a standard class that is known to be thread-safe. If we first fix your file reading thread, so that the main work occurs in the run() method: public class FileReader extends Thread { private final File file; private String[] lines; public FileReader(File file) { this. Java File Class Methods . write(). Once you map a region of the file into memory, then all of your threads can read or write to that block of memory and the OS will synchronizes that memory region with the file periodically (or when you call MappedByteBuffer. Jul 9, 2012 · Even without file locks (i. If you really need this to happen, you should use a ReadWriteLock. Java has many ways to read the file in chunks or line by line, like BufferedReader, Scanner, BufferedInputStream Jun 5, 2015 · In an interview the response should be that this is a consumer-producer problem. The following table depicts several File Class methods: Jun 3, 2014 · I want to query the table in chunks and process each chunk in 10 threads. Sep 7, 2014 · Trying to parallelize the actual reading of a file is probably barking up the wrong tree, as the biggest slowdown will be your file system (even on an SSD). Dec 14, 2011 · I have read many a posts where-in they speak about reading and writing into the file NOT simultaneously using JavaME. opening the file read-only) all the threads after the 1st will just block on the disk read so you make all the other threads wait and whichever one is active when the data becomes available is the one that processes the next block. (start - end) event2 has taken (11025397 - 11025387) = 10ms time. Jul 14, 2013 · I have faced similar problem in past. Dec 28, 2011 · Spawning threads like this is not the way to go. You could implement this using ExecutorService class of java concurrent package. The code below is working fine to read, load and store the content of file. When reading or writing files we need to make Jan 26, 2019 · I am reading multiple files (1000 files of approx size 5mb) from folder. You want to partition the data. Instead, transfer computational work from the reading thread to worker thread(s). 4) The 5 threads should process all the 10 files created in split process. InputStream inputStream = new BufferedInputStream(new FileInputStream(new File("userinfo. forEach(object -> { //Your work on each object goes here, using object }) Use an executor service to submit tasks if you want to use a pool with more threads than the fork-join pool: Oct 12, 2015 · Stack Overflow for Teams Where developers & technologists share private knowledge with coworkers; Advertising & Talent Reach devs & technologists worldwide about your product, service or employer brand. txt", every file has a different date and time. I recommend you use RandomAccessFile to write data to your file. However, you were close using a more primitive approach: You had (before commenting them out) wrapped synchronized(d) around the code in both the consumer and producer, but you did not include the relevant wait() and notify() methods to co-ordinate a single read, followed by a single write. Every utility provides something special e. But note! It's a genuinely Bad Idea to make two threads "take turns" like that, and it's probably a bad idea to let two threads write the same file. This can be used when rapid data extraction and transformation from CSV files are essential, such as in ETL pipelines, data warehousing, and real-time analytics. I want to use Threads. I assume that by "searching a file" you mean finding all lines that contains some word. stream(). The bulk insert is a provision provided in java to insert multiple entries in one go, However from database side, it is n inserts with one commit. e. Aug 29, 2019 · How to read a file using multiple threads in Java when a high throughput(3GB/s) file system is available. Then perform write operation by using Files. Only one connection is required as we are just reading from tables not updating or inserting or deleting from tables. 3. Scanner read = new Scanner (new File("userinfo. Currently we are using Java 5 thread pooling with 10 threads reading the data base in parallel based on a primary key pattern. I'd suggest you to organize it this way: One thread-consumer will consume all data and write it to the file. I'll be using GSON streaming API for the purpose. When the user specifies how many threads to use, you'd configure the pool appropriately, submit the set of file-read jobs, and let the pool sort out the executions. I tried reading the Excel file using XSSFWorkbook, but when the initialization step is executed the program is termination without even entering to catch or finally block using testNG framework Jul 28, 2017 · I have a Java program to do 2 steps: Read files in a directory recursively with multiple threads (10 threads) Send these files to a server by HTTP Post It seems that the first step works well, bu Oct 6, 2013 · If you want to append data to the file, use the constructor that contains an additional boolean argument ( Make it true): public FileWriter(File file,boolean append) throws IOException For example : FileWriter fw = new FileWriter(file. Assign number of threads. Apr 13, 2018 · Improve the logic with : Create on instance of PreparedStatement and use it for every insertion; Use batch to only send big package of insert; This would be done with something like : Jan 31, 2024 · By using multithreading, we can have several threads working simultaneously with each thread responsible, for reading a chunk of data, from the source file and writing it to the destination file. you can use FileReader, BufferedReader, or Scanner to read a text file. Feb 2, 2017 · Reading a file in multithreading mode can only make things slower, since disk drive has to move heads between multiple points of reading. A thread is a lightweight sub-process that runs within a process and shares the same memory space and resources. If you want to read multiple parts of a file at once, the server has to support this and you need a stream for each portion of the file you are downloading. I need to write all these threads output to a file which I was not successful. channels package. Dec 21, 2012 · 1) Have a dispatcher thread read all the file names in your directory. Jun 30, 2019 · inserts cannot be done using multiple threads, no use. May 3, 2015 · If you have multiple threads generating data independently from each other, writing to separate files may be indeed a good option. newFixedThreadPool factory method, and submit each job as a Callable. Jun 1, 2017 · I am stuck here, can someone explain why the consumer thread is running prior producer thread in the below code. I have tried both FileWriter and bufferedWriter classes in Java. getLogger(String) with a Thread-widely unique name. csv, which of course is invalid. Methods for Reading a Text File. Apr 12, 2019 · I want to read multiple files using a thread pool, but I failed. Nov 30, 2024 · Suppose there are two files in the system containing some textual data, your program should read these files concurrently and merge them into one file using JAVA threads. Using BufferedReader class Jun 17, 2010 · If you were to restructure your design just slightly so that loading the file from disk and uploading the file to the client were not done in the same thread, you could wait for the file to stop being accessed simply by locking out new threads from reading this file, then iterating over all of the threads reading from that file and do a join Feb 2, 2021 · Java threading is the concept of using multiple threads to execute different tasks in a Java program. The ExecutorService creates the task for each URL and will analyze and write the file with results asynchronously. This is particularly the case where overall throughput is compromised by network latency. Sep 21, 2018 · This is a pure java response, rather than specifically a selenium response. I now use Grid to run multiple threads at the same time. 1 Using Java BufferReader public class ReadLargeFileByBufferReader { public static Dec 1, 2015 · Most often, the best approach is to have only one thread that does the actual reading from file, since there's little to no benefit in parallelizing the reading. I am trying to redesign the multithreading program for this. Jan 20, 2012 · I'm not quite sure what your aim is from the short description, but I just want to warn you that reading files in parallel from a single hard disk is generally not a good idea, because the mechanical disk head needs to seek the next reading location and so reading with multiple threads will cause it to keep bouncing around and slow things down instead of speeding them up. Apr 9, 2022 · I would only use two threads - one to load up large buffers and push them onto a producer consumer queue, one to pop them and parse the data, byte-by-byte. Each line in the file is a single tuple from the table and I am writing 100s of lines at a time. Using the model producer-consumer: a thread to read the data (main program). Such solution can simplify your code. . Jun 20, 2020 · try { // Get a file channel for the file File file = new File("filename"); FileChannel channel = new RandomAccessFile(file, "rw"). You can Aug 10, 2021 · This use case describes how to process multiple files simultaneously by assigning number of threads on runtime. Feb 27, 2019 · you need to create a Class which will implement callable as below and store futures in a list and finally process the futures as below. Here is the solution to read a single file with multiple threads. Read a single file with multithreading. Oct 8, 2011 · I realize this is kind of late, but I think what you want here is to use the map function in the FileChannel class. That is the use-case that the FAQ says is unsafe. To speed up the processing, I'd like to multithread the 'processsing' part. Nov 4, 2016 · When the user specifies how many threads to use, you'd configure the pool appropriately, submit the set of file-read jobs, and let the pool sort out the executions. Get the list of all files in Array. All worker threads will produce data to the consumer thread in synchronous way. Like wise, you can use it for multiple tables. I'm reading 2 or more files from a folder but i want something faster. Mar 10, 2016 · By using different text file appenders, you can dump the log lines to an appropriately names text file. Long Answer: Threading might improve the read performance if the disks are good at random access (SSD disks are) or if the files are placed on several different disks, but if they're not you're just likely to end up with a lot of cache misses and waiting for the disks to seek the right read position. I want to create 10 threads like 1st thread should read first 1000 rows , second thread should read from 1001 to 2000, 3rd thread should read from 200 Oct 21, 2013 · Other string processor threads will dequeue lines and process them. multithreading to read a file in Java. Once all the lines are read from the file by the single thread then it will return to the caller. txt. I will use Java 8 Nio API, but you are free to use whatever you want to read files Aug 25, 2016 · Create a file reader java whose purpose is to read the biz file and put messages into the JMS queue on the server. Or with multiple threads file writing you can use some mutex or locks implementations. toList()); Using parallel streams for improved performance: Jun 11, 2019 · Wanted to know how to read the same Excel file in java using multi-thread. lines(filePath). In this scenario, multiple threads could be doing read/write operations on the same file. BufferedReader provides buffering of data for fast reading, and Scanner provides parsing ability. read and write files in java using separate threads. By implementing a producer-consumer model and utilizing a BlockingQueue , we ensured thread safety and efficient file operations. Is there any flaw in this implementation? Oct 16, 2011 · How to read a file using multiple threads in Java when a high throughput(3GB/s) file system is available. mkdir() if you still use Java6 but then don't forget to check the return code) to grab a lock on the files you read. A crude but effective partitioner can be made by reading a row from the CSV file and putting it in a Queue. Sep 14, 2011 · Make better use of your CPU. If i use a thread for Jun 29, 2013 · I am currently facing a situation where i have a table with almost 80 millions data and i have to take a dump of that table and store it into a csv file. Nov 15, 2013 · A better way to synchronize this is to use a file lock: How can I lock a file using java (if possible). Where i have to read data from single file, process it and write result in other file. Oct 24, 2023 · Case Study There’s a bunch of files with dumy data transactions on them, and we will try to process them with multithreading in Java and see the difference between with and without multithreading. Creating a File object,passing this to FileReader Object and then cre Aug 10, 2021 · This document helps to solve technical challenges while processing multiple files by assigning threads to each file and process simultaneously. Then each thread can write some unique data into to the file without locking the whole file. Apr 27, 2010 · If all threads are to read all lines from the file, then you should create a separate buffered reader for each thread. Next in try catch block, we have taken some String values as a list because the write method takes byte array only. Code. but you have to co-ordinate your threads as @Thilo points out. How to write in file from multiple threads. How do I do this using threads. May 22, 2022 · I want to read the file as input and compare the time consumed by each event using Java. File locking is used to stop many threads or processes from concurrently accessing the same file. 6. The content being written is actually an entire table (Postgres) being read using CopyManager and written. Jan 24, 2017 · I would use a ThreadPoolExecutor to manage the threads. Better then to let a single thread read the files, send the contents off to worker threads for parallel processing, and then collect the results from the workers. Jan 15, 2011 · read and write files in java using separate threads. Reading and writing a file using threads in java. Updated sample code for reading from file update to map for producer How to Read A CSV File using Multithreading. If you want to use multiple threads, you might consider using one thread for reading the original file, and another thread for writing the copy. And co-ordinate all those threads using CountDown latch. How can consumer thread run when the producer has not put any content. A simple method for implementing file locking in Java is the FileLock class, which comes under java. Either you need to synchronize file access and only write whole record/lines, or you need to have a strategy for allocating regions of the file to different threads e. You can get this value by finding the number of lines in each file, and saving the maximum. 5) I don't want to create same number of threads equal to file count as in that case I may face memory issues. You can do something like this: private class Processor implements Runnable { private final File file; public Feb 18, 2014 · I'm using: java. FYI: Your instructor wants you to do that so that you will learn something about coordinating the activity of different threads. Unsure about using java IO or java NIO. See How to read all lines of a file in parallel in Java 8 for reading one file in parallel. I am thinking to use custom MultiResourcePartioner. I'd be hesitant about looking to multithreading to improve what seems to be a disk-bound operation, particularly if the threads will all end up contending for access to the same file (even if it is only read access). file = file; } @Override public void run() { // Read file here (populate `lines`). While waiting, why not letting other threads use it; Multiple threads can be scheduled to multiple CPU cores; Some problems are naturally to be solved by multi-threading. I'm reading the file line by line since I can't load the whole file in memory. Aug 25, 2016 · Create a file reader java whose purpose is to read the biz file and put messages into the JMS queue on the server. Different instances of MyShelf are not synchronized with each other, so if you have two instances of MyShelf for the same file, they might be updating this file simultaneously. I am getting output by running all the threads. Sep 24, 2015 · An alternative would be to use the java. Extending the thread class; Implementing the runnable interface; Implementing the callable interface; By using the executor framework along with runnable and callable tasks; We will look at callables and the executor framework in a separate blog. 0. 4) Make sure you have some sane naming convention for your output file names so that you don't get threads overwriting each other. file Feb 6, 2017 · Your database presumably lies on a single disk; that disk is connected to a motherboard using a single data cable; if the database server is on a network, then it is connected to that network using a single network cable; so, there is just one path that all that data has to pass through before it can arrive at your different threads and be processed. The way it does all of that is by using a design model, a database-independent image of the schema, which can be shared in a team using GIT and compared or deployed on to any database. The problem arises if there are more than one request on the same file at the same time. Say this is a huge file and you would like to break apart the reading of the file into multiple tasks that are run concurrently. " You want to use multiple threads to read and write the same spreadsheet at the same time. A Java theading program which reads lines of a huge CSV file. How to read a file using multiple threads in Java when a high throughput(3GB/s) file system is available. Aug 13, 2017 · The file holding the URLs list is being read once. By now the file is being read and the content of HTML for each URL is being analyzed and saved in a String. May 11, 2024 · DbSchema is a super-flexible database designer, which can take you from designing the DB with your team all the way to safely deploying the schema. If your concern is about several JVMs writing to the same FileAppender, then i'd suggest two things: using SLF4J as a logging facade; using logback as logging implementation, in prudent mode In our Java application I have requirement to read the around 80 million records from oracle database. getAbsoluteFile(),true); 2. Where in the below multi threading code will the dataquery to extract and send 10 concurrent requests for uploading data to cloud would be? If you want to read multiple parts of a file at once, the server has to support this and you need a stream for each portion of the file you are downloading. However the task is not writing the file. Mar 28, 2016 · 3) I would like to partition these 10 files and would like to process using 5 threads. Use multiResourcePartitioner which will get the directory location and for each file a slave step is created in separate thread; In the Slave step get the file passed from Partitioner and use spring batchs itemreader to read the file; Use the Database item writer( I'm using mybatis batch itemwriter) to push the data to Database. Here's an article from IBM on Java thread pooling. Sample files to be processed. load()), and if you want each thread to work with a Mar 18, 2024 · After that, we get path information about the target file by using Path class available in java. Each thread basically will send the data to an individual node on a 10 node cluster on the cloud. As MadProgrammer said, Java providesBlockingQueue<Integer> to help solve this consumer/producer scenario. This could be plain Java with static void main() Consume the JMS messages in the Message driven beans(You can set the limit on the number of beans to be created in the pool, 50 or 100 depending on the need) if you have mutliple Sep 29, 2016 · it is not necessary to put multiple threads to read from the database because there is a concurrency problem to be managed by the DBMS (similarly to the writing into the file). Tip: To delete a file, read our Java Delete Files chapter. Beware of lines that cross chunk boundaries. // This method blocks until it can retrieve the lock. I will use Java 8 Nio API, but you are free to use whatever you want to read files Feb 23, 2016 · You can use multiple threads writing a to a file e. It comes in handy for threaded applications that require simultaneous access, to a file or to safeguard a file from modifications while it's being used by our application. So, for example, if there are 2 threads, the first reads the first line and, at the same time, the second reads the second line; then the first reads the third line and the second reads the fourth line and they continue reading Nov 19, 2012 · How to read a file using multiple threads in Java when a high throughput(3GB/s) file system is available. 2. Given that each read element from the database will be deleted in the same transaction. csv file which has 10000 rows. Accessing the same document in multiple threads will not work. There is only one issue that we need to make sure of, that no two threads are trying to operate on the same file. Which one to use depends on the Java version you're working with and whether you need to read bytes or characters, and the size of the file/lines etc. 35_128. ThreadPool. Feb 5, 2017 · I am trying to download multiple files that matches a pattern using threads. I have written following Employee class. parallel Multiple file readers might not read the same file because the file has already been taken and locked by another thread that is currently reading the file. Feb 15, 2021 · I was learning multithreading and wanted to read multiple text files in different threads simultaneously using different threads and get the result in single list. If it doesn't, try using a ThreadLocal<Logger> as logger and fill it by using LogManager. Downloading a portion of a File using HTTP Requests. You might get a slight speedup by reading from the file directly into the final buffers and dispatching those buffers to be processed by threads as they are filled, rather than waiting for the entire file to be read before processing. Feb 24, 2011 · Short answer: Read the files sequentially. Use an ExecutorService and specify the pool to be 5. Since processing part was very heavy. Moreover, to enhance the file reading process, we use a BufferedReader that allows us to read the file line by line efficiently: In this tutorial, we’ve learned how to read from and write to files using multiple threads in Java. Using standard streams not using multiple threads: List<ParamsDTO> paramsList = listOfPaths. The reading is achieved by a dataProvider that loads all data into a hashmap. g. Feb 13, 2018 · Actually you can let java 8 parallel stream do the hard work of splitting/mergin etc for you. This parallel approach greatly cuts down on the time it takes to copy the file especially when dealing with files and high-speed disks. 1. Feb 7, 2019 · The thing is that a single call to these two function could not be sufficient to read/write the file entirely. public class ProcessMutlipartFile implements Callable<String> { private Mutlipartfile file; private String temp; private UploadService uploadService; public ProcessMutlipartFile(Mutlipartfile file,String temp, UploadService uploadService ) { this. createDirectory() (or File's . Jun 12, 2018 · The another multi-threaded thread should read the contents of the queue and push it into db. zip I have a while loop reading the buffer until it's clear. Are you trying to read the same file n times completely or chunks a large file parallely using one thread per chunk (divide and conquer) to make faster? – May 9, 2019 · I have a sample. Feb 14, 2024 · In Java, Concurrent file access may cause corruption and errors in the data. The Java FileLock Class provides file locking. getChannel(); // Use the file channel to create a lock on the file. 2) For each file, have the dispatcher thread spawn a worker thread and hand off the file reference. Jul 29, 2015 · I want to configure spring-batch to read all csv files inside a specific folder sequentially. Like event1 has taken (11025373 - 11025373) = 4ms time. map(p -> readFile(p)). I want to use multi-threading in two ways: 10 threads to process files/folders concurrently; 10 threads to process all lines in each file concurrently; In this code, FolderProcessor implements (1), and DocProcessor implements (2). So you should have 1 producer thread reading the file and put the lines in a syncronized collection like a Vector, and you could have n consumer threads taking the lines from the collection and process them. This example shows how to read CSV files using multithreading in Java. nio package. Reading the first part of a file using HTTP Sep 18, 2009 · You don't want to read the files in parallell (disk I/O doesn't parallelize well). Jul 18, 2013 · I followed this question: Now in my case i have 720 files named in this way: "dom 24 mar 2013_00. If this fails, you know someone else is using the file. a log file. Currently i am using a not so professional Nov 11, 2013 · File writing and reading objects using Threads. Jun 4, 2015 · It is a web service client with a pool of 10 threads that churns away, sending requests, batch-style, to a server. Assign remaining files to the last thread. collect(Collectors. Apr 5, 2012 · Although you spawn 20 threads, but there is only one of them is running every time you call the method, the others are just waiting for the lock. util. Jun 25, 2017 · Instead of. There are 10 threads and I have 15 tasks. The following does not work because the delegate will try to open a file named *. nio classes to create a memory-mapped file for sequence. The pattern could match 1 or 5 or 10 files of diff sizes. Once the input is read, it can be given to a worker thread to process. The FileReader class is used to read a file. Jun 17, 2017 · It is possible to read a file parallely using multiple threads. public void readAllFiles(String path) { try ( Jan 4, 2025 · There are several ways to read a plain text file in Java e. But it does not achieve the goal. I have a special use case scenarios where-in my log file (maybe full file or just portion of the file) is uploaded to the server on regular basis. Mar 30, 2015 · Here is my solutions. Great question! I've written a small example (it only uses 6 threads, but can easily be expanded) to illustrate how you could read multiple files (one thread to read each file) and process the data with multiple threads. The single thread which reads the file puts the file contents in a queue and then it gets troublesome to read the queue for specific lines at the same time maintaining a thread safe counter to indicate the lines already read Dec 16, 2011 · Consider simple Java application which should traverse files tree in a disc to find specific pattern in the body of the file. Where in the below multi threading code will the dataquery to extract and send 10 concurrent requests for uploading data to cloud would be? Jul 8, 2016 · Approach B is the logic I pursued but then landed up with a problem of sharing line numbers which are already read between the threads. I am trying to write a single huge file in Java using multiple threads. xuqb hcnr pblrss xrjeehm mcfzp yzhdlp khrwk thdvt elyl fozkpv