Andrew Bogott has uploaded a new change for review. ( 
https://gerrit.wikimedia.org/r/375823 )

Change subject: rabbitmq: increase vm_memory_high_watermark_paging_ratio
......................................................................

rabbitmq: increase vm_memory_high_watermark_paging_ratio

There are two different bad things that might be happening with
rabbit memory.  We might be hitting 50% of vm_memory_high_watermark limit,
which would result in rabbit blocking incoming messages entirely,
or we might be hitting increase vm_memory_high_watermark_paging_ratio
which would not block messages but would cause rabbit to start
frantically paging things out to swap.

We don't really have the option of lifting vm_memory_high_watermark by much
(it's at .4 which means that during garbage collection we could be using
80% of RAM just for rabbit) but this change may improve performance
in the not-quite-worst-case scenario.

This is based on a suggestion in:

https://groups.google.com/forum/#!topic/rabbitmq-users/c0yinUGcAU0

Oddly, that page suggests lifting vm_memory_high_watermark over
.5 which is worrying...

Bug: T170492
Change-Id: I6596f439353ef7a3ed1a8bca2c6a754aeb011754
---
M modules/rabbitmq/files/rabbitmq.config
1 file changed, 1 insertion(+), 1 deletion(-)


  git pull ssh://gerrit.wikimedia.org:29418/operations/puppet 
refs/changes/23/375823/1

diff --git a/modules/rabbitmq/files/rabbitmq.config 
b/modules/rabbitmq/files/rabbitmq.config
index 77b7df7..33d6f29 100644
--- a/modules/rabbitmq/files/rabbitmq.config
+++ b/modules/rabbitmq/files/rabbitmq.config
@@ -249,7 +249,7 @@
    %% persistent and transient) to disk as quickly
    %% as possible, see http://www.rabbitmq.com/lazy-queues.html.
    %%
-   %% {vm_memory_high_watermark_paging_ratio, 0.5},
+   {vm_memory_high_watermark_paging_ratio, 0.8}
 
    %% Selects Erlang VM memory consumption calculation strategy. Can be `rss` 
or `erlang`,
    %% `rss` is the default. Introduced in 3.6.11.

-- 
To view, visit https://gerrit.wikimedia.org/r/375823
To unsubscribe, visit https://gerrit.wikimedia.org/r/settings

Gerrit-MessageType: newchange
Gerrit-Change-Id: I6596f439353ef7a3ed1a8bca2c6a754aeb011754
Gerrit-PatchSet: 1
Gerrit-Project: operations/puppet
Gerrit-Branch: production
Gerrit-Owner: Andrew Bogott <[email protected]>

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