Java and lsof

Update: I found that using Runtime.exec was a bad idea because if you have a 2GB VM footprint then the forked process would require 2G free memory in order to run the lsof command.  We had earlier writte a simple python http rpc server that would allow us to execute native commands(like creating a hardlink or running gunzip) from Java and I changed this code to delagate to RPC call few days back.
So the new code looks like

 public void writeTopCommandOutput(Writer writer) throws IOException {
  String rpcRes = Util.doCommandRpc(rpcUrl, "", ListUtil.create("top", "-n", "2", "-b", "-d", "0.2"));
  writer.write(rpcRes);
 }

 public void writeLsofOutput(Writer writer) throws IOException {
  String pid = getJvmProcessid();
  if (pid != null) {
   pid = pid.trim();
   String rpcRes = Util.doCommandRpc(rpcUrl, "", ListUtil.create("lsof", "-p", pid));
   writer.write(rpcRes);
  }
 }

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I was chasing a customer issue and some threads in threaddump showed that they are stuck doing filer I/O. Now I needed to chase what file paths these threads are accessing as few days ago this customer had expereinced same issue. So I asked operations to give me lsof output and as we are a distribured team and engineers dont have access to production machines.It always takes time to chase people and to a programmer this means lots of context switches and it derails your thought process.  My goal is to eliminate as many hoops in my debugging path so I wrote a JSP to get me lsof output from java. This will be a jsp accessible through internal ips only, hurray from next release onwards one more reason to avoid Operations team in chasing issues.
Here is the method I added in jsp

    public void writeLsofOutput(Writer writer) throws IOException {
        String pid = getJvmProcessid();
        if(pid!=null){
            pid = pid.trim();
            String cmdLsof = "lsof -p " + pid;
            executeCmd(writer, cmdLsof);            
        }
    }

    private void executeCmd(Writer writer, String cmd) throws IOException {
        String output;
        Process child = Runtime.getRuntime().exec(cmd, new String []{});            
        BufferedReader stdInput = new BufferedReader(new InputStreamReader(child.getInputStream()));
        while ((output = stdInput.readLine()) != null) {
            writer.write(output + "\n");
            writer.flush();
        }
        stdInput.close();
    }
    public String getJvmProcessid() throws IOException {
        String pid = null;
        File pidFile = new File(System.getenv("CATALINA_PID"));
        if(pidFile.exists()) {
            FileInputStream fin = new FileInputStream(pidFile);
            List lines = IOUtils.readLines(fin);
            fin.close();
            pid = StringUtils.join(lines.toArray());
        }
        return pid;
    }