我有一个问题,我需要从Java / groovy程序中找出Linux中进程的硬打开和软打开文件限制.当我从终端执行ulimit时,它将为硬打开文件限制和软打开文件限制提供单独的值.

$ulimit -n

1024

$ulimit -Hn

4096

但是,如果我以常规方式执行它,它将忽略软限制并始终返回硬限制值.

groovy> ['bash', '-c', 'ulimit -n'].execute().text

Result: 4096

groovy> ['bash', '-c', 'ulimit -Hn'].execute().text

Result: 4096

如果我缺少什么,请告诉我.我已使用ubuntu 12.04,Groovy版本：1.8.4 JVM：1.6.0_29来执行此操作.

更新：

我在Java中尝试过同样的事情.

import java.io.BufferedReader;

import java.io.IOException;

import java.io.InputStream;

import java.io.InputStreamReader;

import java.io.Reader;

import java.io.StringWriter;

import java.io.Writer;

public class LinuxInteractor {

public static int executeCommand(String command, boolean waitForResponse, OutputHandler handler) {

int shellExitStatus = -1;

ProcessBuilder pb = new ProcessBuilder("bash", "-c", command);

pb.redirectErrorStream(true);

try {

Process shell = pb.start();

if (waitForResponse) {

// To capture output from the shell

InputStream shellIn = shell.getInputStream();

// Wait for the shell to finish and get the return code

shellExitStatus = shell.waitFor();

convertStreamToStr(shellIn, handler);

shellIn.close();

}

}

catch (IOException e) {

System.out

.println("Error occured while executing Linux command. Error Description: "

+ e.getMessage());

}

catch (InterruptedException e) {

System.out

.println("Error occured while executing Linux command. Error Description: "

+ e.getMessage());

}

return shellExitStatus;

}

public static String convertStreamToStr(InputStream is, OutputHandler handler) throws IOException {

if (is != null) {

Writer writer = new StringWriter();

char[] buffer = new char[1024];

try {

Reader reader = new BufferedReader(new InputStreamReader(is,

"UTF-8"));

int n;

while ((n = reader.read(buffer)) != -1) {

String output = new String(buffer, 0, n);

writer.write(buffer, 0, n);

if(handler != null)

handler.execute(output);

}

} finally {

is.close();

}

return writer.toString();

} else {

return "";

}

}

public abstract static class OutputHandler {

public abstract void execute(String str);

}

public static void main(String[] args) {

OutputHandler handler = new OutputHandler() {

@Override

public void execute(String str) {

System.out.println(str);

}

};

System.out.print("ulimit -n : ");

LinuxInteractor.executeCommand("ulimit -n", true, handler);

System.out.print("ulimit -Hn : ");

LinuxInteractor.executeCommand("ulimit -Hn", true, handler);

}

}

该程序的输出：

$java LinuxInteractor

ulimit -n : 4096

ulimit -Hn : 4096

为什么Java中的行为相同.是Java设置ulimit吗？

提前致谢.

解决方法:

Groovy正在其启动脚本中将此限制设置为最大.

在startGroovy：160中：

# Increase the maximum file descriptors if we can.

if [ "$cygwin" = "false" -a "$darwin" = "false" ] ; then

MAX_FD_LIMIT=`ulimit -H -n`

if [ $? -eq 0 ] ; then

if [ "$MAX_FD" = "maximum" -o "$MAX_FD" = "max" ] ; then

MAX_FD="$MAX_FD_LIMIT"

fi

ulimit -n $MAX_FD

if [ $? -ne 0 ] ; then

warn "Could not set maximum file descriptor limit: $MAX_FD"

fi

else

warn "Could not query businessSystem maximum file

descriptor limit: $MAX_FD_LIMIT"

fi

fi

事实证明,jvm自行设置了此限制.我不确定为什么groovy也会改变它.尝试：

java -XX:-MaxFDLimit LinuxInteractor

它将禁用此行为.

标签：groovy,jvm,ulimit,linux,java

来源： https://codeday.me/bug/20191101/1982240.html