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创意设计一个网站/阿里指数官网

admin2025/4/24 8:59:14【news】

简介创意设计一个网站,阿里指数官网,南山商城网站建设哪家服务周到,杭州旅游 网站建设转载自：http://www.rigongyizu.com/jvm-max-threads/ 有应用报出这样的异常“java.lang.OutOfMemoryError: unable to create new native thread”。甚至机器上执行shell命令也会报”-bash: fork: Resource temporarily unavailable”异常。机器上的其他应用如hadoo…

创意设计一个网站,阿里指数官网,南山商城网站建设哪家服务周到,杭州旅游 网站建设转载自：http://www.rigongyizu.com/jvm-max-threads/ 有应用报出这样的异常“java.lang.OutOfMemoryError: unable to create new native thread”。甚至机器上执行shell命令也会报”-bash: fork: Resource temporarily unavailable”异常。机器上的其他应用如hadoo…

转载自：http://www.rigongyizu.com/jvm-max-threads/


有应用报出这样的异常“java.lang.OutOfMemoryError: unable to create new native thread”。甚至机器上执行shell命令也会报”-bash: fork: Resource temporarily unavailable”异常。机器上的其他应用如hadoop也会受影响：

1 2013-08-21 20:15:48,496 FATAL org.apache.hadoop.yarn.event.AsyncDispatcher: Error in dispatcher thread
2 java.lang.OutOfMemoryError: unable to create new native thread
3         at java.lang.Thread.start0(Native Method)
4         at java.lang.Thread.start(Thread.java:640)
5         at org.apache.hadoop.yarn.server.nodemanager.containermanager.localizer.
6 ResourceLocalizationService$LocalizerTracker.handle(ResourceLocalizationService.java:524)
7         at org.apache.hadoop.yarn.server.nodemanager.containermanager.localizer.
8 ResourceLocalizationService$LocalizerTracker.handle(ResourceLocalizationService.java:456)
9         at org.apache.hadoop.yarn.event.AsyncDispatcher.dispatch(AsyncDispatcher.java:128)
10         at org.apache.hadoop.yarn.event.AsyncDispatcher$1.run(AsyncDispatcher.java:77)
11         at java.lang.Thread.run(Thread.java:662)
12 2013-08-21 20:15:48,497 INFO org.apache.hadoop.yarn.event.AsyncDispatcher: Exiting, bbye..

一看以为内存不够导致无法创建新的线程，但是观察机器上的内存还有空闲，猜测是哪个地方对线程创建有限制。

首先需要排除操作系统对线程创建数的限制，参考：《JVM中可生成的最大Thread数量》一文，设置操作系统可以支持创建10万个线程：

1 echo "100000" > /proc/sys/kernel/threads-max
2 echo "100000" > /proc/sys/kernel/pid_max     （默认32768）
3 echo "200000" > /proc/sys/vm/max_map_count   （默认65530）
4 ulimit -u unlimited   (设置max user processes的值)

当前测试环境为：

1 [admin@bufer108081.tbc ~]$ uname -a
2 Linux bufer108081.tbc 2.6.32-220.23.2.ali927.el5.x86_64 #1 SMP Mon Jan 28 14:57:06 CST 2013 x86_64 x86_64 x86_64 GNU/Linux
3 [admin@bufer108081.tbc ~]$ cat /etc/redhat-release
4 Red Hat Enterprise Linux Server release 5.7 (Tikanga)
5 [admin@bufer108081.tbc ~]$ java -version
6 java version "1.7.0_51"
7 Java(TM) SE Runtime Environment (build 1.7.0_51-b13)
8 OpenJDK (Alibaba) 64-Bit Server VM (build 24.45-b08-internal, mixed mode)
9 [admin@bufer108081.tbc ~]$ ulimit -a
10 core file size          (blocks, -c) 0
11 data seg size           (kbytes, -d) unlimited
12 scheduling priority             (-e) 0
13 file size               (blocks, -f) unlimited
14 pending signals                 (-i) 387068
15 max locked memory       (kbytes, -l) 64
16 max memory size         (kbytes, -m) unlimited
17 open files                      (-n) 131072
18 pipe size            (512 bytes, -p) 8
19 POSIX message queues     (bytes, -q) 819200
20 real-time priority              (-r) 0
21 stack size              (kbytes, -s) 10240
22 cpu time               (seconds, -t) unlimited
23 max user processes              (-u) unlimited
24 virtual memory          (kbytes, -v) unlimited
25 file locks                      (-x) unlimited
26 [admin@bufer108081.tbc ~/dev/baoniu]$ free -g
27              total       used       free     shared    buffers     cached
28 Mem:            47         31         15          0          3         25
29 -/+ buffers/cache:          3         44
30 Swap:            0          0          0

测试程序见本文最后面。测试结果：突破了网上所说的32000个线程数，成功创建了 10万个线程。
（由于/proc/sys/kernel/pid_max默认为32768，所以网上很多测试程序测试JVM只能创建32000个线程。）

1 [admin@bufer108081.tbc ~/dev/baoniu]$ java -Xss128k MaxThreadsMain
2 The stack size specified is too small, Specify at least 228k
3 Error: Could not create the Java Virtual Machine.
4 Error: A fatal exception has occurred. Program will exit.
5 [admin@bufer108081.tbc ~/dev/baoniu]$ java -Xss228k MaxThreadsMain
6 4,000 threads: Time to create 4,000 threads was 0.846 seconds
7 8,000 threads: Time to create 4,000 threads was 2.425 seconds
8 12,000 threads: Time to create 4,000 threads was 4.813 seconds
9 16,000 threads: Time to create 4,000 threads was 7.229 seconds
10 20,000 threads: Time to create 4,000 threads was 10.443 seconds
11 24,000 threads: Time to create 4,000 threads was 14.480 seconds
12 28,000 threads: Time to create 4,000 threads was 19.709 seconds
13 32,000 threads: Time to create 4,000 threads was 24.742 seconds
14 36,000 threads: Time to create 4,000 threads was 31.181 seconds
15 40,000 threads: Time to create 4,000 threads was 36.629 seconds
16 44,000 threads: Time to create 4,000 threads was 42.796 seconds
17 48,000 threads: Time to create 4,000 threads was 48.659 seconds
18 52,000 threads: Time to create 4,000 threads was 55.030 seconds
19 56,000 threads: Time to create 4,000 threads was 60.130 seconds
20 60,000 threads: Time to create 4,000 threads was 67.419 seconds
21 64,000 threads: Time to create 4,000 threads was 73.507 seconds
22 68,000 threads: Time to create 4,000 threads was 79.416 seconds
23 72,000 threads: Time to create 4,000 threads was 85.261 seconds
24 76,000 threads: Time to create 4,000 threads was 92.201 seconds
25 80,000 threads: Time to create 4,000 threads was 98.087 seconds
26 84,000 threads: Time to create 4,000 threads was 108.263 seconds
27 88,000 threads: Time to create 4,000 threads was 114.840 seconds
28 92,000 threads: Time to create 4,000 threads was 121.841 seconds
29 96,000 threads: Time to create 4,000 threads was 127.714 seconds
30 After creating 99,410 threads, java.lang.OutOfMemoryError: unable to create new native thread
31         at java.lang.Thread.start0(Native Method)
32         at java.lang.Thread.start(Thread.java:713)
33         at MaxThreadsMain.addThread(MaxThreadsMain.java:43)
34         at MaxThreadsMain.main(MaxThreadsMain.java:13)

创建9W多个线程后，进程占用内存：VIRT=40.5g RES=4.7g，用free -g查看系统还有9G的空闲(free)内存。

JVM最多能启动的线程数参照公式：

1 (MaxProcessMemory - JVMMemory – ReservedOsMemory) / (ThreadStackSize) = Number of threads
  • MaxProcessMemory : 进程的最大寻址空间
  • JVMMemory : JVM内存
  • ReservedOsMemory : 保留的操作系统内存，如Native heap，JNI之类，一般100多M
  • ThreadStackSize : 线程栈的大小，jvm启动时由Xss指定

MaxProcessMemory：如32位的linux默认每个进程最多申请3G的地址空间，64位的操作系统可以支持到46位（64TB）的物理地址空间和47位（128T）的进程虚拟地址空间（linux 64位CPU内存限制）。

JVM内存：由Heap区和Perm区组成。通过-Xms和-Xmx可以指定heap区大小，通过-XX:PermSize和-XX:MaxPermSize指定perm区的大小(默认从32MB 到64MB，和JVM版本有关)。

线程栈ThreadStackSize：

Java程序中，每个线程都有自己的Stack Space。这个Stack Space的空间是独立分配的，与-Xmx和-Xms指定的堆大小无关。Stack Space用来做方法的递归调用时压入Stack Frame。所以当递归调用太深的时候，就有可能耗尽Stack Space，爆出StackOverflow的错误。对于32位JVM，缺省值为256KB，对于64位JVM，缺省值为512KB。最大值根据平台和特定机器配置的不同而不同。如果超过最大值，那么将报告java/lang/OutOfMemoryError消息。

可见，减少Xss指定的线程栈大小能够启动更多的线程，但是线程总数也受到系统空闲内存和操作系统的限制。

总结下影响Java线程数量的因素：

  • Java虚拟机本身：-Xms，-Xmx，-Xss；
  • 系统限制：
    /proc/sys/kernel/pid_max，
    /proc/sys/kernel/thread-max，
    max_user_process（ulimit -u），
    /proc/sys/vm/max_map_count。

ps: 最后发现是这台机器上有个应用代码问题创建了过多的线程，达到系统限制，而影响了YARN和其他应用。一般来说，单机线程数过多可以考虑使用线程池或者更多的服务器。

附测试程序：

1 import java.util.ArrayList;
2 import java.util.List;
3  
4 public class MaxThreadsMain {
5  
6   public static final int BATCH_SIZE = 4000;
7  
8   public static void main(String... args) throws InterruptedException {
9     List<Thread> threads = new ArrayList<Thread>();
10     try {
11       for (int i = 0; i <= 100 * 1000; i += BATCH_SIZE) {
12         long start = System.currentTimeMillis();
13         addThread(threads, BATCH_SIZE);
14         long end = System.currentTimeMillis();
15         Thread.sleep(1000);
16         long delay = end - start;
17         System.out.printf("%,d threads: Time to create %,d threads was %.3f seconds %n", threads.size(), BATCH_SIZE, delay / 1e3);
18       }
19     } catch (Throwable e) {
20       System.err.printf("After creating %,d threads, ", threads.size());
21       e.printStackTrace();
22     }
23  
24   }
25  
26   private static void addThread(List<Thread> threads, int num) {
27     for (int i = 0; i < num; i++) {
28       Thread t = new Thread(new Runnable() {
29         @Override
30         public void run() {
31           try {
32             while (!Thread.interrupted()) {
33               Thread.sleep(1000);
34             }
35           } catch (InterruptedException ignored) {
36             //
37           }
38         }
39       });
40       t.setDaemon(true);
41       t.setPriority(Thread.MIN_PRIORITY);
42       threads.add(t);
43       t.start();
44     }
45   }
46 }

 

附：

MySQL Performance: Hitting Error "Can't Create A New Thread (Errno 11)" On A High Number Of Connections:
Http://Dimitrik.Free.Fr/Blog/Archives/2010/11/Mysql-Performance-Hitting-Error-Cant-Create-A-New-Thread-Errno-11-On-A-High-Number-Of-Connections.Html$ Ulimit -U1024
It Explains 1000 Sessions Limitation ;-)Adding Few Lines More To My "/Etc/Security/Limits.Conf" File:# Cat /Etc/Security/Limits.ConfMysql 	Soft 	Nofile 	10240Mysql 	Hard    Nofile 	40960Mysql 	Soft 	Nproc 	10240Mysql 	Hard    Nproc 	40960
Fixed My Issue! :-))



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