造成这个异常有两类原因:
1.Linux默认的socket描述符数量为1024
抛出这类错误的原因是Linux默认的socket open file的数量为1024,当压力测试达到这个阈值时就会抛出这类错误,下面的文章有详细的解释:
Issue:
How do I set the maximum number of files allowed to be open on a
system
Resolution:
The current setting for maximum number of open files can be viewed
with the command:
ulimit
-n
This number indicates the maximum number of files normal users
(i.e. non-root) can have open in a single session. Note that for
the root user, ulimit -n will sometimes output 1024 even after
following the procedure to increase the maximum number of open
files. This won't effect root's ability to open large numbers of
files, as only normal users are bound by this value.
To increase the maximum number of open files beyond the default
of 1024, two changes to the system may be necessary. In these
examples, we will increase the maximum number of open files to the
arbitrary value of 2048. All changes need to be made by the root
user and users will need to log out and log back in before the
changes will take effect.
1. Configure the system to
accept the desired value for maximum number of open files Check the
value in /proc/sys/fs/file-max to see if it is larger than the
value needed for the maximum number of open files:
# cat /proc/sys/fs/file-max
If the value isn't large enough, echo an appropriate number into
the variable and add the change to /etc/sysctl.conf to make it
persistent across reboots. If the number is already larger than the
value you wish to use, skip to step 2.
# echo 2048 > /proc/sys/fs/file-max
and edit /etc/sysctl.conf to include the line:
fs.file-max = 2048
2. Set the value for
maximum number of open files In the file /etc/security/limits.conf,
below the commented line that reads
#<domain>
<type>
<item>
<value>
add this line:
* - nofile 2048
This line sets the default number of open file descriptors for
every user on the system to 2048. Note that the "nofile" item has
two possible limit values under the
<type> header: hard and soft. Both
types of limits must be set before the change in the maximum number
of open files will take effect. By using the "-" character, both
hard and soft limits are set simultaneously.
The hard limit represents the maximum value a soft limit may have
and the soft limit represents the limit being actively enforced on
the system at that time. Hard limits can be lowered by normal
users, but not raised and soft limits cannot be set higher than
hard limits. Only root may raise hard limits.
When increasing file limit descriptors, you may want to simply
double the value. For example, if you need to increase the default
value of 1024, increase the value to 2048 first. If you need to
increase it again, try 4096, etc.
==================================================================
1。ulimit -a 查看系统目前资源限制的设定。
[root@test security]# ulimit -a
core file
size
(blocks, -c) 0
data seg
size
(kbytes, -d) unlimited
file
size
(blocks, -f) unlimited
max locked
memory
(kbytes, -l) unlimited
max memory
size
(kbytes, -m) unlimited
open
files
(-n) 1024
pipe
size
(512 bytes, -p) 8
stack
size
(kbytes, -s) 8192
cpu
time
(seconds, -t) unlimited
max user
processes
(-u) 7168
virtual
memory
(kbytes, -v) unlimited
[root@test security]#
通过以上命令,我们可以看到open files 的最大数为1024
那么我们可以通过一下命令修改该参数的最大值
2. ulimit -n 4096
[root@test security]# ulimit -n 4096
[root@test security]# ulimit -a
core file
size
(blocks, -c) 0
data seg
size
(kbytes, -d) unlimited
file
size
(blocks, -f) unlimited
max locked
memory
(kbytes, -l) unlimited
max memory
size
(kbytes, -m) unlimited
open
files
(-n) 4096
pipe
size
(512 bytes, -p) 8
stack
size
(kbytes, -s) 8192
cpu
time
(seconds, -t) unlimited
max user
processes
(-u) 7168
virtual
memory
(kbytes, -v) unlimited
这样我们就修改了系统在同一时间打开文件资源的最大数,基本解决以上问题。
另外我们可以通过lsof
-p [进程的
pid]来查看系统当前打开的文件资源,可以了解不同时期系统的文件资源的使用情况,可根据情况进行系统资源的配置。
===================================================================
从这里学到的linux的命令
查看进程所占的文件描述符 lsof -p 390 | wc -l
查看系统的各种资源限制或者更改这个限制
ulimit -a
2.HttpClient建立Socket时
,post.releaseConnection()并没有真正关闭连接,而是将该连接提交给
MultiThreadedHttpConnectionManager,等待复用.
可以设置post方法的header,增加
post.addRequestHeader( "Connection",
"close");
client.getParams().setBooleanParameter(
"http.protocol.expect-continue"
,
false
);
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