Add memory fix post

_posts/2024-01-17-i-once-reduced-response-time-by-80-percent-with-one-line-change.md

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+---
+layout: post
+title:  I once reduced response time by 80% with one line change
+date:   2024-01-17
+image: /assets/img/memory-fix.png
+---
+
+Shortly after I started a job I noticed we were storing, for each of our customers, Stripe customer data as JSON in 
+the DB. I actually said in a meeting that I thought it would be better to just store only the attributes we needed 
+as columns instead, but I was told that _I should not worry about it and that it worked beautifully_. It was 
+actually worse than that because Stripe allows to expand responses when querying their API so we were storing 
+customer data with their subscriptions; after that when we wanted to read this information we would hydrate Stripe 
+objects from the [Stripe ruby gem](https://github.com/stripe/stripe-ruby).
+
+So a few months go by and I'm asked to investigate some memory issues on production. I start chasing down the issue 
+on my development machine, run some memory profiling and notice the Stripe gem is doing a lot of memory allocations. 
+Thought that couldn't be the issue so I start looking somewhere else. The actual pages with the biggest memory 
+usage allowed embedding custom images and CSS so I thought the issue would be there. I spent 
+some time looking into that, but I couldn't find what was the cause. So I started commenting out one piece of code at 
+a time until I noticed it was those Stripe JSON objects that were causing these huge memory spikes. 
+
+Everytime we wanted to check what type of Stripe subscription the customer had or if it was active we would hydrate 
+a Stripe object with the subscription data from the DB. The temporary fix I did was to memoize the hydrated Stripe 
+subscription so this inefficient process was done only once per request and not many times, I think I counted 6 
+times in a single request.
+
+On my development machine I noticed an 84% reduction in memory allocation, so I knew it would improve things. When 
+we pushed the code to production I couldn't believe what I was seeing. I was looking at our APM tool to check 
+performance and had to refresh the page a few times because I thought it wasn't working right, mean response time 
+had dropped 80%, it also looked flat now instead of having lots of peaks and valleys. 
+
+<p class='center'>
+  <img src='/assets/img/memory-fix.png' alt='Memory Fix' />
+  The pink solid line represents new response time and the pink dotted line old response time
+</p>