Nginx运行过程中的一些状态信息存放在内存中，可通过ngx_http_stub_status_module模块来查看。
要查看这些状态信息，首先在执行configure时指定--with-http_stub_status_module参数，然后在Nginx配置文件中增加一个location，如下：
location /status {
stub_status on;
}
当前可查看的状态信息包括：
Active connections: xxx
server accepts handled requests
xxx xxx xxx
Reading: xxx Writing: xxx Waiting: xxx1) Active connections - 当前打开的连接数（活动/非活动），包含到后端服务器的连接。
2) accepts - 从启动到当前为止所有已接受的连接数。
3) handled - 从启动到当前为止所有已处理的连接数，等于“2)”减去那些已接受但立即断开的连接。
4) requests - 从启动到当前为止所有已处理的请求数。
5) Reading - 当前正在读取请求头的连接数。
6) Writing - 当前正在读取请求体、处理请求和输出响应的连接数。
7) Waiting - 非活动/空闲的Keepalive连接数，等于“1)”减去“5)”和“6)”所得到的连接数。
单进程工作模式下状态信息存放在全局变量中，如下：
ngx_atomic_t ngx_stat_accepted0;
ngx_atomic_t *ngx_stat_accepted = &ngx_stat_accepted0;
ngx_atomic_t ngx_stat_handled0;
ngx_atomic_t *ngx_stat_handled = &ngx_stat_handled0;
ngx_atomic_t ngx_stat_requests0;
ngx_atomic_t *ngx_stat_requests = &ngx_stat_requests0;
ngx_atomic_t ngx_stat_active0;
ngx_atomic_t *ngx_stat_active = &ngx_stat_active0;
ngx_atomic_t ngx_stat_reading0;
ngx_atomic_t *ngx_stat_reading = &ngx_stat_reading0;
ngx_atomic_t ngx_stat_writing0;
ngx_atomic_t *ngx_stat_writing = &ngx_stat_writing0;
主从进程工作模式下状态信息存放在共享内存中，如下：
/* cl should be equal or bigger than cache line size */
cl = 128;
size = cl /* ngx_accept_mutex */
+ cl /* ngx_connection_counter */
+ cl; /* ngx_temp_number */
#if (NGX_STAT_STUB)
size += cl /* ngx_stat_accepted */
+ cl /* ngx_stat_handled */
+ cl /* ngx_stat_requests */
+ cl /* ngx_stat_active */
+ cl /* ngx_stat_reading */
+ cl; /* ngx_stat_writing */
#endif
shm.size = size;
shm.name.len = sizeof("nginx_shared_zone");
shm.name.data = (u_char *) "nginx_shared_zone";
shm.log = cycle->log;
if (ngx_shm_alloc(&shm) != NGX_OK) {
return NGX_ERROR;
}
shared = shm.addr;
ngx_accept_mutex_ptr = (ngx_atomic_t *) shared;
ngx_accept_mutex.spin = (ngx_uint_t) -1;
if (ngx_shmtx_create(&ngx_accept_mutex, (ngx_shmtx_sh_t *) shared,
cycle->lock_file.data)
!= NGX_OK)
{
return NGX_ERROR;
}
ngx_connection_counter = (ngx_atomic_t *) (shared + 1 * cl);
(void) ngx_atomic_cmp_set(ngx_connection_counter, 0, 1);
ngx_log_debug2(NGX_LOG_DEBUG_EVENT, cycle->log, 0,
"counter: %p, %d",
ngx_connection_counter, *ngx_connection_counter);
ngx_temp_number = (ngx_atomic_t *) (shared + 2 * cl);
tp = ngx_timeofday();
ngx_random_number = (tp->msec << 16) + ngx_pid;
#if (NGX_STAT_STUB)
ngx_stat_accepted = (ngx_atomic_t *) (shared + 3 * cl);
ngx_stat_handled = (ngx_atomic_t *) (shared + 4 * cl);
ngx_stat_requests = (ngx_atomic_t *) (shared + 5 * cl);
ngx_stat_active = (ngx_atomic_t *) (shared + 6 * cl);
ngx_stat_reading = (ngx_atomic_t *) (shared + 7 * cl);
ngx_stat_writing = (ngx_atomic_t *) (shared + 8 * cl);
#endif
