linux上进程打开句柄最大值是1024，但为什么epoll号称能管理上百万句柄呢？

        linux上进程打开句柄最大值是1024，  这只是默认情况而已：

[email protected]:~$ 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) 3306
max locked memory       (kbytes, -l) 64
max memory size         (kbytes, -m) unlimited
open files                      (-n) 1024
pipe size            (512 bytes, -p) 8
POSIX message queues     (bytes, -q) 819200
real-time priority              (-r) 0
stack size              (kbytes, -s) 8192
cpu time               (seconds, -t) unlimited
max user processes              (-u) 3306
virtual memory          (kbytes, -v) unlimited
file locks                      (-x) unlimited
[email protected]:~$ 
           

       可见， 默认确实是1024,  此时， 无法做高并发服务器， 必须修改上限则行。

       来看一个真实的在线跑的高并发服务器：

xxxxxx$  ulimit -a
core file size          (blocks, -c) unlimited
data seg size           (kbytes, -d) unlimited
scheduling priority             (-e) 0
file size               (blocks, -f) unlimited
pending signals                 (-i) 1027980
max locked memory       (kbytes, -l) 64
max memory size         (kbytes, -m) unlimited
open files                      (-n) 2000000
pipe size            (512 bytes, -p) 8
POSIX message queues     (bytes, -q) 819200
real-time priority              (-r) 0
stack size              (kbytes, -s) 8192
cpu time               (seconds, -t) unlimited
max user processes              (-u) 1027980
virtual memory          (kbytes, -v) unlimited
file locks                      (-x) unlimited
           

       上限是200万个， 足够了， epoll快来管理管理。