bug: 500 error when bench limit-count plugin

[UnderTreeTech]

limit count conf:
policy: redis
count: 100
time_window: 60
key: remote_addr
os: CentOS 7.6
benchmark tool: apache benchmark

I got runtime error which result in 500 response when i bench 1million request, 1k concurrency by ab.It seems red:ttl(key) return nil in limit-count-redis.lua. The follow snippet is runtime error detail:

lua entry thread aborted: runtime error: .../apisix/apisix/plugins/limit-count/limit-count-redis.lua:76: attempt to compare nil with number
stack traceback:
coroutine 0:
        .../apisix/apisix/plugins/limit-count/limit-count-redis.lua: in function 'incoming'
        /usr/local/apisix/apisix/plugins/limit-count.lua:121: in function 'phase_fun'
        /usr/local/apisix/apisix/init.lua:147: in function 'run_plugin'
        /usr/local/apisix/apisix/init.lua:385: in function 'http_access_phase'
        access_by_lua(nginx.conf:161):2: in main chunk

Is it a bug? @membphis @moonming

[membphis]

yes, that is a bug. we need to check the return value first.
welcome PR ^_^

[UnderTreeTech]

Another issue: in my bench scenario, the redis connections is much more than pool size, there are many timewait , close wait connections, Is pool connection is not reusable long connection? BTW, my pool size is 100 and keepalive timeout is 10 minutes. @membphis

[membphis]

one issue focus on one thing. if you have another question, please create a new issue.

[shuaijinchao]

I will deal with this problem.