diff options
| -rw-r--r-- | src/rabbit_memory_monitor.erl | 37 |
1 files changed, 3 insertions, 34 deletions
diff --git a/src/rabbit_memory_monitor.erl b/src/rabbit_memory_monitor.erl index 03b3bfdec2..7237b82559 100644 --- a/src/rabbit_memory_monitor.erl +++ b/src/rabbit_memory_monitor.erl @@ -34,40 +34,6 @@ %% It receives statistics from all queues, counts the desired %% queue length (in seconds), and sends this information back to %% queues. -%% -%% Normally, messages are exchanged like that: -%% -%% (1) (2) (3) -%% Timer | | -%% v v -%% Queue -----+--------+-----<***hibernated***>-------------> -%% | ^ | ^ ^ -%% v | v | | -%% Monitor X--*-+--X---*-+--X------X----X-----X+-----------> -%% -%% Or to put it in words. Queue periodically sends (casts) 'push_queue_duration' -%% message to the Monitor (cases 1 and 2 on the asciiart above). Monitor -%% _always_ replies with a 'set_queue_duration' cast. This way, -%% we're pretty sure that the Queue is not hibernated. -%% Monitor periodically recounts numbers ('X' on asciiart). If, during this -%% update we notice that a queue was using too much memory, we send a message -%% back. This will happen even if the queue is hibernated, as we really do want -%% it to reduce its memory footprint. -%% -%% -%% The main job of this module, is to make sure that all the queues have -%% more or less the same number of seconds till become drained. -%% This average, seconds-till-queue-is-drained, is then multiplied by -%% the ratio of Total/Used memory. So, if we can 'afford' more memory to be -%% used, we'll report greater number back to the queues. In the out of -%% memory case, we are going to reduce the average drain-seconds. -%% To acheive all this we need to accumulate the information from every -%% queue, and count an average from that. -%% -%% real_queue_duration_avg = avg([drain_from_queue_1, queue_2, queue_3, ...]) -%% memory_overcommit = allowed_memory / used_memory -%% desired_queue_duration_avg = real_queue_duration_avg * memory_overcommit - -module(rabbit_memory_monitor). @@ -231,6 +197,9 @@ internal_update(State = #state{memory_limit = Limit, callbacks = Callbacks}) -> %% available memory / used memory MemoryRatio = Limit / erlang:memory(total), + %% if all queues are pushed to disk, then Sum will be 0. If memory + %% then becomes available, unless we do the following, we will + %% never allow queues to come off disk. Sum1 = case MemoryRatio > 1.05 of true -> Sum + 1; false -> Sum |