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PERF: message_bus will be deferred by server when flooded

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The message_bus performs a fair amount of work prior to hijacking requests
this change ensures that if there is a situation where the server is flooded
message_bus will inform client to back off for 30 seconds + random(120 secs)

This back-off is ultra cheap and happens very early in the middleware.

It corrects a situation where a flood to message bus could cause the app
to become unresponsive

MessageBus update is here to ensure message_bus gem properly respects
Retry-After header and status 429.

Under normal state this code should never trigger, to disable raise the
value of DISCOURSE_REJECT_MESSAGE_BUS_QUEUE_SECONDS, default is to tell
message bus to go away if we are queueing for 100ms or longer
This commit is contained in:
Sam Saffron
2019-08-09 17:47:44 +10:00
parent b500ef77d7
commit 1f47ed1ea3
5 changed files with 49 additions and 6 deletions
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16
lib/middleware/request_tracker.rb
View File

@ -139,17 +139,23 @@ class Middleware::RequestTracker
end
def self.populate_request_queue_seconds!(env)
if !env['REQUEST_QUEUE_SECONDS']
if queue_start = env['HTTP_X_REQUEST_START']
queue_start = queue_start.split("t=")[1].to_f
queue_time = (Time.now.to_f - queue_start)
env['REQUEST_QUEUE_SECONDS'] = queue_time
end
end
end
def call(env)
result = nil
log_request = true
# doing this as early as possible so we have an
# accurate counter
if queue_start = env['HTTP_X_REQUEST_START']
queue_start = queue_start.split("t=")[1].to_f
queue_time = (Time.now.to_f - queue_start)
env['REQUEST_QUEUE_SECONDS'] = queue_time
end
::Middleware::RequestTracker.populate_request_queue_seconds!(env)
request = Rack::Request.new(env)