select多路復用壓力測試

1、shell指令碼

#!

/bin/bash
#!/bin/bash
for(
(i=1
;i<=
1100
;i=i+1)
)do./a & 
echo "$i" 
sleep 0.005
done
echo "***************************8"
cat test.log | grep "f"
|wc -l 
cat test.log | grep "o"
|wc -l
echo "***************************"

#include

#include
#include
#include
#include
#include
/* see notes */
#include
#include
#include
#include
#include
#define msg "hello"
intmain()
//printf("create socket is successful:[%d]\n",cli_fd);if(
connect
(cli_fd,
(struct sockaddr *
)&cli_addr,
sizeof
(cli_addr)
)<0)
//printf("connect is successful\n");
/* rv = read(cli_fd, buf, sizeof(buf));
if(rv <0)
printf("data is :[%s]",buf);
*/if(
write
(cli_fd,
&msg,
sizeof
(msg)
)<0)
// printf("write is successful,\n");
memset
(buf,0,
sizeof
(buf));
rv =
read
(cli_fd, buf,
sizeof
(buf));
if(rv<0)
// printf("read is successful,data is [%s]\n",buf);
printf
("ok");
close
(cli_fd)
;exit(0);}

#include

#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#define array_size(x) (sizeof(x)/sizeof(x[0]))
//求陣列元素的個數
static
inline
void
msleep
(unsigned
long ms)
;int
socket_server_init
(char
*listen_ip,
int listen_port)
;int main (
int argc,
char
**ar**)
printf
("%s server start to listen on port %d\n"
,"59.110.42.24"
,serv_port)
;for
(i=0
; i<
array_size
(fds_arry)
; i++
)//遍歷陣列
fds_arry[0]
= listenfd;
//將第乙個陣列賦值為listenfd
for(;;
) rv =
select
(maxfd+1,
&rdset,
null
,null
,null);
//select函式的返回值是就緒描述符的數目
if(rv <0)
else
if( rv ==0)
if(fd_isset
(listenfd,
&rdset)
)//判斷指定描述符是否在集合中
found =0;
for(i=
0; i<
array_size
(fds_arry)
;i++)}
if(!found)
}else
memset
(buf,0,
sizeof
(buf));
rv =
read
(fds_arry[i]
,buf,
sizeof
(buf));
if( rv <0)
else
if(rv ==0)
elseif(
write
(fds_arry[i]
, buf , rv)
<0)
}}}}
cleanup:
close
(listenfd)
;return0;
}static
inline
void
msleep
(unsigned
long ms)
intsocket_server_init
(char
*listen_ip,
int listen_port)
setsockopt
(listenfd, sol_socket, so_reuseaddr,
&on,
sizeof
(on));
memset
(&servaddr,0,
sizeof
(servaddr));
servaddr.sin_family=af_inet;
servaddr.sin_port =
htons
(listen_port);if
(!listen_ip )
else}if
(bind
(listenfd,
(struct sockaddr *
)&servaddr,
sizeof
(servaddr)
)<0)
if(listen
(listenfd,13)
<0)
cleanup:
if(rv <0)
close
(listenfd)
;else
rv = listenfd;
return rv;
}

max就是描述符中最大的哪乙個，比如上面的圖最大的就是10，將要連線的客戶端放入fd_set中，然後用select阻塞，接著如果有乙個或者多個客戶端來了資料，select就將&rset相應的位置1，其他全部位0，比如描述符是10，和11，那麼就在&rset 10和11位置1，其他全部為0 .這樣做的目的是後面會進行乙個fd_isset判斷描述符在&rset是否存在，如果存在才能進行讀取資料。

缺點

1、只能最多建立1024個描述符。（可修改）

2、每次都要進行乙個複雜度位o（n）的迴圈
3、每次rset都需要重新復位
4、開銷大，他的描述符會從使用者態拷貝到核心態