我目前有一個程序在單線程模式下讀取文件(非常大),並創建搜索索引,但在單線程環境下索引太長。如何在多線程模式下讀取文件?
現在我試圖讓它在多線程模式下工作,但不確定實現這一點的最佳方式。
我的主程序創建一個緩衝讀取器,並將實例傳遞給線程,線程使用緩衝讀取器實例讀取文件。
我不認爲這是按預期工作,而是每個線程一次又一次地讀同一行。
有沒有辦法讓線程只讀取不被其他線程讀取的行?我需要分割文件嗎?有沒有一種方法來實現這一點,而不分裂文件?
樣品主程序:
import java.io.BufferedReader;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.util.ArrayList;
public class TestMTFile {
public static void main(String args[]) {
BufferedReader reader = null;
ArrayList<Thread> threads = new ArrayList<Thread>();
try {
reader = new BufferedReader(new FileReader(
"test.tsv"));
} catch (FileNotFoundException e1) {
e1.printStackTrace();
}
for (int i = 0; i <= 10; i++) {
Runnable task = new ReadFileMT(reader);
Thread worker = new Thread(task);
// We can set the name of the thread
worker.setName(String.valueOf(i));
// Start the thread, never call method run() direct
worker.start();
// Remember the thread for later usage
threads.add(worker);
}
int running = 0;
int runner1 = 0;
int runner2 = 0;
do {
running = 0;
for (Thread thread : threads) {
if (thread.isAlive()) {
runner1 = running++;
}
}
if (runner2 != runner1) {
runner2 = runner1;
System.out.println("We have " + runner2 + " running threads. ");
}
} while (running > 0);
if (running == 0) {
System.out.println("Ended");
}
}
}
主題:
import java.io.BufferedReader;
import java.io.IOException;
public class ReadFileMT implements Runnable {
BufferedReader bReader = null;
ReadFileMT(BufferedReader reader) {
this.bReader = reader;
}
public synchronized void run() {
String line;
try {
while ((line = bReader.readLine()) != null) {
try {
System.out.println(line);
} catch (Exception e) {
}
}
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
你專注於錯誤的部分。這是你需要多線程的索引,而不是閱讀。 –
我非常懷疑瓶頸是_read_文件。這很可能是索引。 – jtahlborn