KeepAlive

local function send()
    for i = 1, count do
        local ssdb_db, err = ssdb:new()
        local ok, err = ssdb_db:connect(SSDB_HOST, SSDB_PORT)
            return         -- 这里添加了 return 语句
        else
            local key, err = ssdb_db:qpop(something)
            if not key then
                ngx.log(ngx.ERR, "ssdb qpop err:", err)
                -- other operations
            end
            -- 把语句移动到了这里，只会把成功的连接加入到连接池
            ssdb_db:set_keepalive(SSDB_KEEP_TIMEOUT, SSDB_KEEP_COUNT)
        end