help request: keeping redis connection alive

[mayeter]

Description

Hello, I've been working on the limit-req plugin with redis and I realized apisix creates a new connection for every single request, so I think maybe I can alter this behaviour and if I can keep a single connection, it could perform faster after getting rid of three-way handshake.

Maybe you tried it already and it is a bad idea but I really need to get higher numbers 🙏

I've played a little in apisix/plugins/limit-req/limit-req-redis.lua

function _M.new(plugin_name, conf, rate, burst)
    local red, err = redis.new(conf)
    if not red then
        return red, err
    end
    local self = {
        red = red,
        conf = conf,
        plugin_name = plugin_name,
        burst = burst * 1000,
        rate = rate * 1000,
    }

    return setmetatable(self, mt)
end


function _M.incoming(self, key, commit)
    local conf = self.conf
    local red = self.red
    if not red then
        return red, err
    end

    return util.incoming(self, red, key, commit)
end

So it creates a connection once and keeps it under "self". My problem here is that it somehow terminates this connection after first request and the rest throws this error:

2024/06/25 18:29:23 [error] 242482#242482: *3933 [lua] limit-req.lua:171: phase_func(): failed to limit req: closed, client: x.x.x.x, server: _, request: "GET /test1/x HTTP/2.0", host: "xyz.com"

I failed to find the trigger that closes connection. Could you guide me please?

Environment

• APISIX version (run apisix version): 3.9
• Operating system (run uname -a): Ubuntu 22.04
• OpenResty / Nginx version (run openresty -V or nginx -V): openresty/1.21.4.1
• etcd version, if relevant (run curl http://127.0.0.1:9090/v1/server_info):
• APISIX Dashboard version, if relevant:
• Plugin runner version, for issues related to plugin runners:
• LuaRocks version, for installation issues (run luarocks --version):