英文:
Find Process Count in Java
问题
我可以使用以下命令启动Process，在启动多个进程后，我想控制在某一点上要保留多少个进程。
例如：
- 在0到50的范围内，在
for循环中启动一个Process。 - 当总活动进程为5时，暂停
for循环。 - 一旦从5下降到4或3，恢复
for循环。
我尝试了下面的代码，但是似乎漏掉了一些内容。
public class OpenTerminal {
public static void main(String[] args) throws Exception {
int counter = 0;
for (int i = 0; i < 50; i++) {
while (counter < 5) {
if (runTheProc().isAlive()) {
counter = counter + 1;
} else if (!runTheProc().isAlive()) {
counter = counter - 1;
}
}
}
}
private static Process runTheProc() throws Exception {
return Runtime.getRuntime().exec("cmd /c start cmd.exe /c \"dir && ping localhost\"");
}
}
此外，如何找出有多少个活动进程？以便我可以同时控制活动进程数量。
英文:
I am able to launch Process with the help of below command and after launching multiple processes I want to control how many processes I want to keep at some point.
For example:
- Initiate a
Processinside aforloop of range 0 to 50 - Pause the
forloop once total active processes are 5 - Resume
forloop once it drop from 5 to 4 or 3 ...
I tried below code, but I am missing something.
public class OpenTerminal {
public static void main(String[] args) throws Exception {
int counter = 0;
for (int i = 0; i < 50; i++) {
while (counter < 5) {
if (runTheProc().isAlive()) {
counter = counter + 1;
}else if(!runTheProc().isAlive()) {
counter = counter-1;
}
}
}
}
private static Process runTheProc() throws Exception {
return Runtime.getRuntime().exec("cmd /c start cmd.exe /c \"dir && ping localhost\"");
}
}
Also, how to find out how many process are active? So that I can control active processes at a time.
答案1
得分: 1
你可以使用具有固定大小的线程池。
例如：
public static void main(String[] args) throws Exception {
ExecutorService threadPool = Executors.newFixedThreadPool(5);
for (int i = 0; i < 50; i++) {
threadPool.submit(runTheProc);
}
}
private static final Runnable runTheProc = () -> {
Process process;
try {
process = Runtime.getRuntime().exec("cmd /c start cmd.exe /c \"dir && ping localhost\"");
} catch (Exception e) {
throw new RuntimeException(e);
}
while (process.isAlive()) { }
};
英文:
You can use thread pool with fixed size.
For example:
public static void main(String[] args) throws Exception {
ExecutorService threadPool = Executors.newFixedThreadPool(5);
for (int i = 0; i < 50; i++) {
threadPool.submit(runTheProc);
}
}
private static final Runnable runTheProc = () -> {
Process process;
try {
process = Runtime.getRuntime().exec("cmd /c start cmd.exe /c \"dir && ping localhost\"");
} catch (Exception e) {
throw new RuntimeException(e);
}
while (process.isAlive()) { }
};
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