我需要从文件夹中读取图像并为其生成校验和。大约有330760张图像。以下是代码:
package com.test;
import java.io.FileInputStream;
import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.LinkedBlockingQueue;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;
import java.util.stream.Stream;
import org.apache.commons.codec.digest.DigestUtils;
public class FileTest2 {
private void readFiles() throws IOException {
try (Stream<Path> filePathStream = Files
.walk(Paths.get("d:\\codebase\\images"))) {
filePathStream.parallel().forEach(filePath -> {
String checksumSHA256 = "";
try {
checksumSHA256 = DigestUtils.sha384Hex(new FileInputStream(filePath.toString()));
} catch (IOException e) {
e.printStackTrace();
}
if (Files.isRegularFile(filePath)) {
System.out.println(checksumSHA256);
System.out.println(filePath);
System.out.println("\n");
}
});
}
}
public static void main(String[] args) throws IOException {
long startTime = System.currentTimeMillis();
FileTest2 fileTest = new FileTest2();
fileTest.readFiles();
long endTime = System.currentTimeMillis();
System.out.println("Total Time took: " + (endTime - startTime) / 1000);
}
}
花了大约36分钟。
系统配置:
核心数:8
内存:32 GB(15-17 GB可用)。其余的内存正在由另一台服务器使用。
36分钟太多了。有没有办法提高性能?
答案 0 :(得分:2)
正如其他人指出的那样,您不终止执行程序。要查看实际时间,请运行以下
public static void main(String[] args) throws Exception {
long startTime = System.currentTimeMillis();
FileTest fileTest = new FileTest();
fileTest.readFiles();
long endTime = System.currentTimeMillis();
System.out.println("Total Time took: "+ (endTime-startTime)/1000);
}
注意:至少从您发布的代码中,没有理由使用ExecutorService