java为什么在这段代码中ProcessBuilder的执行会影响主线程？

Question

在该程序中，主线程运行10分钟后，开始时间和当前时间之间的差值增加到1秒以上，最多8秒。为什么会发生这种情况process builder会影响主线程执行

java版本“1.6.0_26”

Java（TM）SE运行时环境（build 1.6.0_26-b03）

Java HotSpot（TM）服务器虚拟机（构建20.1-b02，混合模式

OS: Solaris 

---

import java.io.BufferedReader;

import java.io.InputStreamReader;

import java.util.ArrayList;

import java.util.Date;

import java.util.List;

import java.util.concurrent.ExecutorService;

import java.util.concurrent.Executors;


public class ExecTest {

        public ExecThread getExecThread(String cmd, int callNumberStart) {
                return new ExecThread(cmd, callNumberStart);
        }

        public class ExecThread implements Runnable {

                private String cmd;
                private int callNumberStart;

                public ExecThread(String cmd, int callNumberStart) {
                        this.cmd = cmd;
                        this.callNumberStart = callNumberStart;
                }

                public String executeCommand(String origLegCallId, String cmd) {
                        Process process = null;
                        String cmdOutput = null;
                        try {
                                List<String> command = new ArrayList<String>();
                                String[] splittedCmd = cmd.split("\\s+");
                                for(String tmp : splittedCmd){
                                        command.add(tmp);
                                }
                                ProcessBuilder builder = new ProcessBuilder(command);
                                process = builder.start();
                                process.waitFor();
                                InputStreamReader isr = new InputStreamReader(process.getInputStream());
                                BufferedReader br = new BufferedReader(isr);
                                String line = null;
                                cmdOutput = new String();
                                while ((line = br.readLine()) != null) {
                                        cmdOutput = cmdOutput + line;
                                }
                        } catch (Exception ex) {
                                ex.printStackTrace();
                                cmdOutput = null;
                        }
                        return cmdOutput;
                }


                @Override
                public void run() {
                        while (true) {
                                System.out.println(callNumberStart + ":: " + Thread.currentThread().getName() + ":: Start " +
 new Date());
                                String output=executeCommand("" + callNumberStart, cmd);
                                System.out.println(Thread.currentThread().getName()+"Output is:"+output);
                                System.out.println(callNumberStart + ":: " + Thread.currentThread().getName() + ":: End " + n
ew Date());
                                callNumberStart++;
                        }

                }

        }

        public static void main (String args []) {
                int numberOfThread =100;
                String cmd = /home/run.sh; //{sleep 5;echo 'hello'}
                ExecutorService es = Executors.newFixedThreadPool(numberOfThread);

                ExecTest test=new ExecTest();

                for (int i = 1; i <= numberOfThread; i++) {
                        es.submit(test.getExecThread(cmd, i*10000));
                }

                while (true) {

                        long startTime = System.currentTimeMillis();
                        for (int j=0; j<5; j++) {
                                try {
                                        Thread.sleep(200);
                                } catch (InterruptedException e) {
                                        // TODO Auto-generated catch block
                                        e.printStackTrace();
                                }
                        }
                        System.out.println("Processing Time:: " + (System.currentTimeMillis()-startTime));
                }

        }

}

Answer 1

因为这个{}

查看javadoc here

编辑1：

在第二次查看代码之后，您似乎没有关闭流，因此相当快地消耗了大量资源（许多线程正在执行IO）