# Tracing a Memory-leak in a Long Running Eventmachine Application
author
: P.S.V.R
allotted-time
: 30m
theme
: debian
# gist
* What's Eventmachine and How was it used in HuantengSmart
* Memory-leak Symptom
* Diagnosis
* Treatment
# What's Eventmachine
* event-processing library, provides event-driven I/O using the Reactor pattern (反应堆模式)
* single-threaded, scalability limited by _calling request handlers synchronously_ & _demultiplexer_
* not to be confused with Actor model, ex. erlang/celluloid
* not to be confused with Proactor pattern, ex. Boost.Asio
# What's Eventmachine (cont.)
{:relative_height='80' reflect_ratio='0.5'}
# nonblocking handler sample (by Longyi)
http = EventMachine::HttpRequest.new(@@url).put :body => @@post_params[@@request_count%2]
http.callback { received http.response if http.response }
{: lang="ruby"}
# blocking handler sample
uri = URI(@@url)
res = Net::HTTP.get_response(uri)
received res
{: lang="ruby"}
# How was EM used in HuantengSmart
* Connecting all TelePort routers
* Hosting a HTTP server for internal Rails to send requests
* Hosting a WebSocket server for mobile apps
* Hosting (yet another) WebSocket server for web pages
# Memory-leak Symptom
| Uptime | Observed Memory Footprint |
|---------|--------|
| Startup | 73M |
| 34min | 84M |
| 1h | 92M |
| 1h44m | 106M |
| 3h10m | 130M |
| 30h | 3.47G |
# Memory-leak...
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