[linux] nginx配置线程池（thread tool）

1、nginx配置是需要添加–with-threads参数

./configure --with-threads

2、在合适的上下文（http、server、location）配置 aio threads

in the ‘main’ context
thread_pool default threads=32 max_queue=65536;
in the ‘http’, ‘server’, or ‘location’ context
aio threads=default;
上面例子定义了一个名称为default的线程池，线程数为32个，最大任务队列为65536，如果任务队列超过负载，nginx会提示报错
thread pool "NAME" queue overflow: N tasks waiting

3、可以配置多个独立的线程池用于不通的配置文件使用：

in the ‘main’ context

thread_pool one threads=128 max_queue=0;
thread_pool two threads=32;

http {
    server {
        location /one {
            aio threads=one;
        }

        location /two {
            aio threads=two;
        }

    }
    # ...
}

如果不指定max_queue，默认值为65536，上面例子设置为0，这种情况线程池只能处理和线程池数相等的任务，没有任务等待。

4、如果服务器有多块硬盘，可以使用分割用户+proxy_cache的方法提高性能

假设有三块挂载盘/mnt/disk1, /mnt/disk2, or /mnt/disk3
in the ‘main’ context

thread_pool pool_1 threads=16;
thread_pool pool_2 threads=16;
thread_pool pool_3 threads=16;

http {
    proxy_cache_path /mnt/disk1 levels=1:2 keys_zone=cache_1:256m max_size=1024G
                     use_temp_path=off;
    proxy_cache_path /mnt/disk2 levels=1:2 keys_zone=cache_2:256m max_size=1024G
                     use_temp_path=off;
    proxy_cache_path /mnt/disk3 levels=1:2 keys_zone=cache_3:256m max_size=1024G
                     use_temp_path=off;

    split_clients $request_uri $disk {
        33.3%     1;
        33.3%     2;
        *         3;
    }  
    server {
        # ...
        location / {
            proxy_pass http://backend;
            proxy_cache_key $request_uri;
            proxy_cache cache_$disk;
            aio threads=pool_$disk;
            sendfile on;
        }
    }
}