The redis command ‘blpop’ can't block the programme about lua-resty-redis HOT 4 CLOSED

@leeguevara Thank you for the report but I have several comments for you first:

1. I cannot reproduce this issue on my side. Please provide a minimal and still complete example that I can run locally. I have no idea how your InitializeRedis and KeepAliveRedis are actually defined.

2. You should do proper error handling for the blpop call in your Lua code, that is, do something like this:

   local msg, err = redis_handle:blpop("list1", "0");
   if not msg then
       ngx.log(ngx.ERR, "blpop failed: ", err)
       return ngx.exit(500)
   end
   

3. The ngx_lua cosocket read operations have a different timeout guard of 60 seconds: https://github.com/chaoslawful/lua-nginx-module#lua_socket_read_timeout You need to adjust this by configuring this directive or call the set_timeout method of your resty.redis objects.

from lua-resty-redis.

Thank you.

The original test code as follow:

the conf file:

#user  nobody;
worker_processes 4;
worker_cpu_affinity 0001 0010 0100 1000;

#pid        logs/nginx.pid;

events {
    worker_connections  3072;
}

http {
    include       mime.types;
    default_type  application/octet-stream;

    sendfile        on;
    #tcp_nopush     on;

    keepalive_timeout  75s;

    #gzip  on;

    server {
        listen 80 backlog=1024;
        server_name  localhost;

        location / {
            root   html;
            index  index.html index.htm;
        }

    location /TestRedis {
        content_by_lua_file 'lua/AppStore/Test_Redis.lua';
    }

        error_page   500 502 503 504  /50x.html;
        location = /50x.html {
            root   html;
        }
    }
}

Test_Redis.lua

cjson=require "cjson";
redis=require "resty.redis";

function InitializeRedis(host, port, timeout)
    local handle=redis:new();

    if timeout
    then
        handle:set_timeout(timeout);
    end

    if handle
    then
        local ok, err=handle:connect(host, port);
    end
    return handle, err;
end

function KeepAliveRedis(db_handle, timeout)
    if timeout==nil
    then
        db_handle:set_keepalive(10000, 100);
    else
        db_handle:set_keepalive(timeout, 100);
    end
end

function Testblpop()
    local count=1;
    local msg=nil;
    local err='';
    local redis_handle, err=InitializeRedis(redis_host, redis_port);

    while true
    do
        ngx.log(ngx.NOTICE, string.format("count: %d", count));

        msg, err=redis_handle:blpop("list1", '0');

        ngx.log(ngx.NOTICE, string.format("msg: %s", cjson.encode(msg)));

        count=count+1;

        ngx.sleep(1);
    end

    KeepAliveRedis(redis_handle);
end


Testblpop();

I access Testblpop using curl

curl "http://localhost/TestRedis"

Thanks a lot ^_^

from lua-resty-redis.

Sorry. It's not a problem. It's my fault.

The "blpop" blocks my connect. After a while, the redis connection will be timeout. Then an error will occur, the "blpop" function return. So it seems that the "blpop" function couldn't block the programme.

I also have a question.

"how to make the redis connection never be timeout?"

I have tried the "set_timeout" function.

Thanks a lot.

from lua-resty-redis.

Hello!

On Tue, Dec 31, 2013 at 2:54 AM, leeguevara [email protected] wrote:

I also have a question.

"how to make the redis connection never be timeout?"

I have tried the "set_timeout" function.

Well, you can just use a very large timeout value, like 1576800000000
for 50 years :)

-agentzh

from lua-resty-redis.