问题解决了，从JDK1.7升级到JDK8就好了。这个是JDK自己的bug，可以查JDK的buglist

执行下面的代码会导致内存泄漏，实在不知道为啥了，求助
if(SystemUtils.IS_OS_LINUX){
Process process = Runtime.getRuntime().exec(cmd);
InputStream is = process.getInputStream();
InputStreamReader isr = new InputStreamReader(is);
BufferedReader br = new BufferedReader(isr);
StringBuilder buf = new StringBuilder();
try {

String line;
while ((line = br.readLine()) != null) {
buf.append(line).append("\n");
}
if (process.waitFor() != 0) {
return "CMD1 Error";
}
return buf.toString();
} catch (java.io.IOException e) {
e.printStackTrace();
return "CMD1 Error";
} finally{
is.close();
isr.close();
br.close();
process.destroy();
}
}