nginx node.js 上传大文件时出现502 Bad Gateway

环境 ubuntu 14.04 nginx 1.10.2 node.js 0.10.32 express 3.5.1 sequelize 1.7.0 设置了最大连接数

	pool: {
      maxConnections: 1000,
      maxIdleTime: 30
    }

mysql 5.5

我遇到的问题：

1. 在使用nginx做反向代理时： 当文件小于100M时 上传成功 当文件大于100M时 上传失败 前端收到502 Bad Gateway 后端node.js报错mysql too many connections
2. 不使用nginx直接访问 任意文件都可以上传成功

我所查到的最类似与我的问题为 502 Bad Gateway with “large” file uploads

现阶段我所做的工作 根据网上查询到方法，修改nginx的配置 加上了如下的 在http模块中加入

    keepalive_timeout  600;
    send_timeout 10m;
    client_header_timeout 10m;
    client_body_timeout 10m;
    client_max_body_size 512m;
    large_client_header_buffers 8 32k;

在server中加入

 	client_max_body_size 512m;
    proxy_buffer_size 512k;
    proxy_buffers 4 1024k;
    proxy_busy_buffers_size 1024k;

其中这部分的配置将512k修改为128k 1024k修改为256k 有成功过一次 完整的nginx.conf文件如下

	user  root root;
	worker_processes  6;
	worker_cpu_affinity 000000000000000000000001 000000000000000000000010 000000000000000000000100 000000000000000000001000 000000000000000000010000 000000000000000000100000;
	worker_rlimit_nofile 65530;
	events {
		worker_connections  65530;
	}
	http {
    include       mime.types;
    default_type  application/octet-stream;
    sendfile        on;
    tcp_nopush     on;
    tcp_nodelay on; 
    #keepalive_timeout  0;
    keepalive_timeout  600;
    send_timeout 10m;
    client_header_timeout 10m;
    client_body_timeout 10m;
    client_max_body_size 512m;
    large_client_header_buffers 8 32k;
    gzip  on;
    upstream tvbox {
        server 127.0.0.1:9123;
    }
    server {
        listen       80;
        server_name  myip;
        client_max_body_size 512m;
        proxy_buffer_size 512k;
        proxy_buffers 4 1024k;
        proxy_busy_buffers_size 1024k;
        location / {
                keepalive_timeout 600;
                proxy_set_header   X-Real-IP            $remote_addr;
                proxy_set_header   X-Forwarded-For  $proxy_add_x_forwarded_for;
                proxy_set_header   Host                   $host;
                proxy_set_header   X-NginX-Proxy    true;
                proxy_set_header   Connection "";
                proxy_http_version 1.1;
                proxy_pass         http://tvbox;
                proxy_redirect off;
        }
        location ~ ^/(softwares|ad|images_activity|images_recommends|images_film|images_screen_protector|apk_dir|app_shop_dir)/  {
                root    /uploads;
                autoindex on;
                autoindex_exact_size off;
                autoindex_localtime on;
         }
    }
	}

node.js中的接收上传文件的部分代码如下

     module.exports.uploadfile = function (req, res) {
	 var software_version = {};
    var source = req.files.uploadingfile.path;
    var size = req.files.uploadingfile.size;
    var minetype = req.files.uploadingfile.type;
    var suffix = getExtension(req.files.uploadingfile.name);
    software_version.minetype = minetype;
    async.series([
        // 计算文件HASH
        function(callback){
            var sha1 = crypto.createHash('sha1');
            var s = fs.ReadStream(source);
            s.on('data', function (d) {
                sha1.update(d);
            });
            s.on('end', function () {
                var hash = sha1.digest('hex');
                callback(null, hash);
            });
        },
        // 获取文件大小
        function(callback){
            fs.stat(source, function(err, stats){
                if(err) throw err;
                callback(null, stats.size);
            });
        }
    ], function(err, results){
        var hash = results[0];
        var size = results[1];
		//查询数据库中是否有记录
        db.software_version.find({
            where: {
                id: req.body.id
            }
        }).success(function(item){
            if(item == null)
            {
                // 创建
                db.software_version.create({
                    hash: hash,
                    size: size,
                    suffix: suffix,
                    minetype: minetype,
                    url: '/softwares/'+hash+suffix
                }).success(function (software_version) {
                    res.json({
                        status: 'ok',
                        result: software_version
                    });
                }).failure(function (error) {
                    res.json({
                        status: 'error',
                        result: {
                            msg: '数据库错误,请联系管理员'
                        }
                    })
                });
            }else{
                // 更新
                db.software_version.update({
                    hash: hash,
                    size: size,
                    suffix: suffix,
                    minetype: minetype,
                    url: '/softwares/'+hash+suffix
                }, {
                    id: item.id
                }).success(function (affected_rows) {
                    db.software_version.find(item.id).success(function(row){
                        res.json({
                            status: 'ok',
                            result: row.dataValues
                        });
                    });
                }).failure(function (error) {
                    res.json({
                        status: 'error',
                        result: {
                            msg: '数据库错误,请联系管理员'
                        }
                    })
                });;
            }
        });
    });
     };

最后求各位大神看下能否有什么办法解决这个问题