JVM最多能创建多少个线程: unable to create new native thread
2017-06-07 11:23
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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:
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:
当前测试环境为:
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。)
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:
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:
附:
[html] view
plain copy
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 -U
1024
It Explains 1000 Sessions Limitation ;-)
Adding Few Lines More To My "/Etc/Security/Limits.Conf" File:
# Cat /Etc/Security/Limits.Conf
Mysql SoftNofile10240
Mysql HardNofile40960
Mysql SoftNproc 10240
Mysql HardNproc 40960
Fixed My Issue! :-))
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.. |
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) |
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 |
12 | scheduling |
13 | file size (blocks, -f) unlimited |
14 | pending |
15 | max locked memory (kbytes, -l) 64 |
16 | max |
17 | open files (-n) 131072 |
18 | pipe |
19 | POSIX message queues (bytes, -q) 819200 |
20 | real- time priority (-r) 0 |
21 | stack |
22 | cpu time (seconds, -t) unlimited |
23 | max |
24 | virtual v ) unlimited |
25 | file locks (-x) unlimited |
26 | [admin@bufer108081.tbc ~/dev/baoniu]$ free -g |
27 | total used free shared buffers cached |
28 | Mem: |
29 | -/+ |
30 | Swap: |
(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) |
JVM最多能启动的线程数参照公式:
1 | (MaxProcessMemory - JVMMemory – ReservedOsMemory) / (ThreadStackSize) = Number of threads |
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 | } |
[html] view
plain copy
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 -U
1024
It Explains 1000 Sessions Limitation ;-)
Adding Few Lines More To My "/Etc/Security/Limits.Conf" File:
# Cat /Etc/Security/Limits.Conf
Mysql SoftNofile10240
Mysql HardNofile40960
Mysql SoftNproc 10240
Mysql HardNproc 40960
Fixed My Issue! :-))
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