1 /*
2  * Copyright (C) 2016 The Android Open Source Project
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  *      http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16 
17 import static java.nio.file.StandardOpenOption.*;
18 import java.nio.file.*;
19 import java.io.*;
20 import java.util.*;
21 
22 public class Main {
23     private static final String TEMP_FILE_NAME_PREFIX = "oflimit";
24     private static final String TEMP_FILE_NAME_SUFFIX = ".txt";
25 
main(String[] args)26     public static void main(String[] args) throws IOException {
27 
28         // Exhaust the number of open file descriptors.
29         List<File> files = new ArrayList<File>();
30         List<OutputStream> streams = new ArrayList<OutputStream>();
31         try {
32             for (int i = 0; ; i++) {
33                 File file = createTempFile();
34                 files.add(file);
35                 streams.add(Files.newOutputStream(file.toPath(), CREATE, APPEND));
36             }
37         } catch (Throwable e) {
38             if (e.getMessage().contains("Too many open files")) {
39                 System.out.println("Message includes \"Too many open files\"");
40             } else {
41                 System.out.println("Unexpected exception:");
42                 e.printStackTrace();
43             }
44         }
45 
46         // Now try to create a new thread.
47         try {
48             Thread thread = new Thread() {
49                 public void run() {
50                     System.out.println("thread run.");
51                 }
52             };
53             thread.start();
54             thread.join();
55         } catch (Throwable e) {
56             System.out.println(e.getMessage());
57         }
58 
59         for (int i = 0; i < streams.size(); i++) {
60           streams.get(i).close();
61         }
62 
63         for (int i = 0; i < files.size(); i++) {
64           files.get(i).delete();
65         }
66         System.out.println("done.");
67     }
68 
createTempFile()69     private static File createTempFile() throws Exception {
70         try {
71             return  File.createTempFile(TEMP_FILE_NAME_PREFIX, TEMP_FILE_NAME_SUFFIX);
72         } catch (IOException e) {
73             System.setProperty("java.io.tmpdir", "/data/local/tmp");
74             try {
75                 return File.createTempFile(TEMP_FILE_NAME_PREFIX, TEMP_FILE_NAME_SUFFIX);
76             } catch (IOException e2) {
77                 System.setProperty("java.io.tmpdir", "/sdcard");
78                 return File.createTempFile(TEMP_FILE_NAME_PREFIX, TEMP_FILE_NAME_SUFFIX);
79             }
80         }
81     }
82 }
83