http - 请求计数的增加以“错误:套接字挂起”结束
问题描述
当请求数量增加时,后端服务/nginx 代理开始响应“错误:套接字挂起”。设置如下。
操作系统:CentOS 6
Express JS 服务 -> nginx 作为代理 -> Gunicorn 运行的烧瓶应用程序
JS 应用程序同时向另一个服务发送多个请求,当请求计数超过 ~100 时,它开始返回错误响应。如果计数较低,则一切正常。
我遵循了 Gunicorn 文档中的 nginx 示例配置 + 增加超时限制 + 增加 nginx 打开文件限制。我也尝试过keepalive选项,但问题仍然存在。Gunicorn 没有显示任何错误。
nginx配置片段:
upstream app_server {
server 127.0.0.1:8000 fail_timeout=0;
keepalive 100;
}
server {
listen 5001;
client_max_body_size 4G;
keepalive_timeout 300;
root /path/to/app/current/public; # static files
location / {
try_files $uri @proxy_to_app;
}
location @proxy_to_app {
# Timeouts
proxy_read_timeout 300;
proxy_connect_timeout 300;
proxy_send_timeout 300;
send_timeout 300;
proxy_http_version 1.1;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_set_header X-Forwarded-Proto $scheme;
proxy_set_header Host $http_host;
proxy_redirect off;
proxy_pass http://app_server;
}
}
从代理收到的错误响应:
{ RequestError: Error: socket hang up
at new RequestError (/home/pm2deploy/apps/app-backend/source/node_modules/request-promise-core/lib/errors.js:14:15)
at Request.plumbing.callback (/home/pm2deploy/apps/app-backend/source/node_modules/request-promise-core/lib/plumbing.js:87:29)
at Request.RP$callback [as _callback] (/home/pm2deploy/apps/app-backend/source/node_modules/request-promise-core/lib/plumbing.js:46:31)
at self.callback (/home/pm2deploy/apps/app-backend/source/node_modules/request/request.js:185:22)
at Request.emit (events.js:160:13)
at Request.onRequestError (/home/pm2deploy/apps/app-backend/source/node_modules/request/request.js:881:8)
at ClientRequest.emit (events.js:160:13)
at Socket.socketOnEnd (_http_client.js:423:9)
at Socket.emit (events.js:165:20)
at endReadableNT (_stream_readable.js:1101:12)
at process._tickCallback (internal/process/next_tick.js:152:19)
name: 'RequestError',
message: 'Error: socket hang up',
cause: { Error: socket hang up
at createHangUpError (_http_client.js:330:15)
at Socket.socketOnEnd (_http_client.js:423:23)
at Socket.emit (events.js:165:20)
at endReadableNT (_stream_readable.js:1101:12)
at process._tickCallback (internal/process/next_tick.js:152:19) code: 'ECONNRESET' },
error: { Error: socket hang up
at createHangUpError (_http_client.js:330:15)
at Socket.socketOnEnd (_http_client.js:423:23)
at Socket.emit (events.js:165:20)
at endReadableNT (_stream_readable.js:1101:12)
at process._tickCallback (internal/process/next_tick.js:152:19) code: 'ECONNRESET' },
options:
{ method: 'PUT',
uri: 'http://localhost:5001/transformers/segmentAvg',
qs:
{ stdMultiplier: 2,
segmentLeft: 1509366682333,
segmentRight: 1509367401685 },
body: { index: [Array], values: [Array] },
headers: {},
json: true,
callback: [Function: RP$callback],
transform: undefined,
simple: true,
resolveWithFullResponse: false,
transform2xxOnly: false },
response: undefined }
添加:
在 OS 日志中记录了以下条目:
possible SYN flooding on port X. Sending cookies.
解决方案
内核套接字积压达到限制并丢弃了以下请求。
原因:在 Red Hat Enterprise Linux 中,由于 LISTEN 套接字缓冲区已满,内核丢弃 TCP 连接
增加内核套接字积压限制
检查当前值:
# sysctl net.core.somaxconn
net.core.somaxconn = 128
增加值:
# sysctl -w net.core.somaxconn=2048
net.core.somaxconn = 2048
通过再次查看确认更改:
# sysctl net.core.somaxconn
net.core.somaxconn = 2048
坚持改变:
echo "net.core.somaxconn = 2048" >> /etc/sysctl.conf
增加应用程序套接字侦听积压
uWSGI的配置参数
listen=1024
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