iRule for rate limit unexpected behaviour

iRule 2 https://devcentral.f5.com/questions/irule-rate-limiting-with-queuing-of-requests-57583comment64016:

when RULE_INIT {

         Tweak the request limit and interval 
        set static::request_limit 30                ;count
        set static::request_interval 1              ;sec

         Tweak the queue size, timeout and retry interval
        set static::queue_size 250                  ;count
        set static::queue_timeout 5                 ;sec
        set static::queue_retry_interval 1000       ;msec
    }

    when HTTP_REQUEST {

         Enforce limits only on GET requests...

        if { [HTTP::method] eq "GET" } then {

             Calculate a unique request ID to track the request...
            set request_id "[TMM::cmp_unit][clock clicks]"

             Compute table labels for request and queued limiter...
            set request_label "R_[HTTP::host]:[IP::client_addr]"
            set queue_label "Q_[HTTP::host]"

             Checking if request limit has been reached...

            if { [set request_rate [table keys -count -subtable $request_label]] < $static::request_limit } then {

                 Max request rate is not exceeded. Insert a new entry to request limiter table...
                table set -subtable $request_label $request_id "1" indef $static::request_interval 
                log local0.debug "Debug: $request_id : Allow: Request rate for $request_label is $request_rate / $static::request_interval seconds"
                 Allowing the request to pass...

            } else {

                 Max request rate is exceeded. Holding the request to check queue slots...
                log local0.debug "Debug: $request_id : Hold: Request rate for $request_label is $request_rate / $static::request_interval seconds"

                 Checking if queue has a free slot....
                if { [set queue_size [table keys -count -subtable $queue_label]] < $static::queue_size } then {

                     Queue is not exceeded. Insert a new entry to queue limiter table...
                    table set -subtable $queue_label $request_id "1" indef $static::queue_timeout 
                    log local0.debug "Debug: $request_id : Queued: Queue counter for $queue_label is $queue_size"

                     Initialize queue timer...
                    set queue_time 0

                     Enforcing the queue loop timeout timer...
                    while { $static::queue_timeout * 1000 > $queue_time } {

                         Pausing the ongoing HTTP request for queue retry interval
                        after $static::queue_retry_interval

                         Checking if request limit has been lowered...
                        if { [set request_rate [table keys -count -subtable $request_label]] < $static::request_limit } then {

                             Max request rate has been lowered. Insert a new entry to our request rate limiter...
                            table set -subtable $request_label $request_id "1" indef $static::request_interval 
                            log local0.debug "Debug: $request_id : Queue Release: Requests rate for $request_label is now $request_rate / $static::request_interval seconds"

                             Removing this request from request queue
                            table delete -subtable $queue_label $request_id

                             Exiting this iRule and allowing the request to pass...
                            return

                        } else {

                             Max request rate is still exceeded. Queueing the request another cycle...

                            log local0.debug "Debug: $request_id : Queue Retry: Requests rate for $request_label is now $request_rate / $static::request_interval seconds"
                            incr queue_time $static::queue_retry_interval

                        }
                    }

                     Queued request has been timed out. Dropping the request...
                    log local0.debug "Debug: $request_id : Queue Fail: Requests rate for $request_label is now $request_rate / $static::request_interval seconds"
                    HTTP::respond 429 content "Request Denied: Exceeded requests/sec limits"

                } else {

                     Maximum queue size has been exceeded. Dropping the request...
                    log local0.debug "Debug: $request_id : Queue Exceeded: Queue counter for $queue_label is $queue_size"
                    HTTP::respond 429 content "Request Denied: Exceeded requests/sec limits"

                }
            }
        }
    }