对于出现/bin/sh: fork: retry: 资源暂时不可用这样的报错时，说明Linux的open file最大连接数已满。
1、通过ulimit -a命令查看可以看到该用户的max user processes值
-bash-4.1$ ulimit -a
core file size (blocks, -c) 0
data seg size (kbytes, -d) unlimited
scheduling priority (-e) 0
file size (blocks, -f) unlimited
pending signals (-i) 127209
max locked memory (kbytes, -l) 64
max memory size (kbytes, -m) unlimited
open files (-n) 65535
pipe size (512 bytes, -p) 8
POSIX message queues (bytes, -q) 819200
real-time priority (-r) 0
stack size (kbytes, -s) 10240
cpu time (seconds, -t) unlimited
max user processes (-u) 1024
virtual memory (kbytes, -v) unlimited
file locks (-x) unlimited
2、解决的方法如下：
切换至root用户依次执行
2.1 centos6中修改/etc/security/limits.d/90-nproc.conf文件，centos7中修改/etc/security/limits.d/20-nproc.conf。
将npoc设置最大。修改后，内容如下：
cat /etc/security/limits.d/90-nproc.conf
* soft nproc 65535
root soft nproc unlimited
2.2 修改/etc/security/limits.conf，增加nofile。修改方法如下：
echo "* - nofile 65535" >> /etc/security/limits.conf
echo "* - noproc 65535" >> /etc/security/limits.conf
其中：
-
- 代表针对所有用户，noproc 是代表最大进程数，nofile 是代表最大文件打开数
-
- 的意思为soft 和hard 全部限制
2.3 /sbin/sysctl -p 使配置生效
-bash-4.1$/sbin/sysctl -p
-bash-4.1$ ulimit -a
core file size (blocks, -c) 0
data seg size (kbytes, -d) unlimited
scheduling priority (-e) 0
file size (blocks, -f) unlimited
pending signals (-i) 127209
max locked memory (kbytes, -l) 64
max memory size (kbytes, -m) unlimited
open files (-n) 65535
pipe size (512 bytes, -p) 8
POSIX message queues (bytes, -q) 819200
real-time priority (-r) 0
stack size (kbytes, -s) 10240
cpu time (seconds, -t) unlimited
max user processes (-u) 65535 # Linux的open file最大连接数已经修改
virtual memory (kbytes, -v) unlimited
file locks (-x) unlimited
