[rabbitmq-discuss] Possible memory leak in the management plugin

[Pavel]

Hi again,

I finally got back to these tests and have some results to share.

TL/DR: baring some oddities there is a clear change of pattern in agg_stats
table growth when using 3.3.4 comparing to 3.1.5. While in 3.1.5 it grows
seemingly unbounded, 3.3.4 keeps it stable at certain level. More details
below.

I have two identical boxes in the lab one running Erlang 15B + RabbitMQ
3.1.5 and other one on Erlang 17 +  RabbitMQ 3.3.4. In both environments I
run my load generation test (slightly modified from what was shared earlier
in this thread) using JDK7 + com.rabbitmq:amqp-client:3.3.4 with the
following parameters:

RabbitSmasher 500 100 10000000 499 false false

What this does is:
- creates 499 exchanges
- creates 499 queues and binds them 1-1 to exchanges
- creates 1 connection with 500 channels
- publishes messages at the rate of 100/s rotating through 500 channels and
picking exchange/routing key sequentially (so that each of 249500
channel/queue permutations is hit once every ~40 minutes)

During the test I'm sampling mgmt_db memory on both boxes every 5 seconds
using this query:

/usr/sbin/rabbitmqctl eval
'{process_info(global:whereis_name(rabbit_mgmt_db),memory),[{T,
ets:info(T,size), ets:info(T,memory)} || T <-lists:sort(ets:all()),
rabbit_mgmt_db <- [ets:info(T, name)]]}.'

Running this for 24+ hours produced these results:

- Box running 3.1.5 crashed after ~38 hours, it's unclear though what caused
the crash (could be unrelated to the test)
- Box running 3.3.4 continued to execute the test after ~69 hours 

- 3.1.5 had agg_stats memory constantly growing for the entire test duration
(38h), ending at ~269K words
- 3.3.4 had agg_stats memory stabilized around ~65K words at ~5 hours mark
-- that said, 3.3.4 had a few huge outliers, reaching up to ~600K words

There are also quite interesting observations for total mgmt_db memory in
both tests:

- In 3.1.5 mgmt_db had a ~2 hour long spike/plateau at 2.5Gb, then went back
to under 1Gb for the remainder of the test
- In 3.3.4 mgmt_db never went above 700Mb, but after ~60 hours of run
dramatically changed the pattern staying under 100Mb for the remainder of
the test (except few outliers)

The most odd thing in these results is number of records in agg_stats table
in 3.3.4: after reaching certain limit (which remained stable for the entire
duration of test on 3.1.5), it began to jump between 253642 and
500046.

Attaching excel file with data, will post images next.

Test_5_-_charts.zip
<http://rabbitmq.1065348.n5.nabble.com/file/n36797/Test_5_-_charts.zip>  



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