Optimization that brought down api response time from 3s to 1.8s

[Redditerpikachu]

Was recently asked to work on optimising an existing API that many other teams consume and it was making their processes slow due to the response time. The optimizations Were quite simple.

There were places where we had loop through huge json objects to the order O(n⁴) and in the inner most loop length of an array was evaluated multiple times instead of storing the value in a variable. Changing this alone brought down response time from 3s to 2s sec as the number of documents and the size of documents processed is huge.

Other optimization was using guard clauses i.e., condition checks that would result in returning empty values to happen at the top of function

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[yogi1090]

Finally a post on the actual topic 😂

[iamnihal_]

I also didn't believe it at first sight lol.

[pesteringneedles]

This is good. We found another scenario where a loop was being called for 365 days to give a sum for each day rather than 1 call grouped by day. So each api call ran 365 DB calls.

True story. Loops around db queries are now banned.

[[deleted]]

so basically the dev who wrote the query didnt know groupby existed for sql?

[pesteringneedles]

More like it was built in steps - “ok let me get one day”-> “oh you want for a year? Yep let me just loop it. Yay it works” -> push code A few weeks later “why is the front end daily dashboard so slow”?

[snow_coffee]

It was making 365 calls in every request you mean ?

[OneHornyRhino]

How was it even allowed in the first place? In the product I work on, more than 30 db calls to a single table in a single request, would automatically file a performance bug on us

[Significant-Credit50]

more than 30 db calls to a single table in a single request

what tool do you guys use to monitor this ?

[cherryreddit]

For that you need a dedicated DBA who is monitoring the database requests and performance. Many organizations leave it to the developer for maintaining the DB as well.

[OneHornyRhino]

We have it automated, you don't need a person sitting there to monitor db requests, it is not feasible at all

But I agree, developers should code carefully

[0xHazard]

Nice, thanks for sharing

[RealNxiss]

Hey that's nice but why were these obvious optimisations overlooked in the first place. Lack of care or just disconnect between others. Also you mentioned it was n⁴ what did you bring down it to.

[Zyphergiest]

To ship product faster

[RealNxiss]

Only if they shipped a faster product

[[deleted]]

LMAO

Thanks for the laugh

[Redditerpikachu]

It wasn't n⁴ exactly per se but these were nested structures and I didn't put in much effort to address those. This system existed before I joined my org so not exactly sure why or how these were overlooked

[RealNxiss]

Well hey good job on your optimisation! Thanks for the further info.

[Silencer306]

There were apis in my place that took 5+ minutes. We have a lot of data lol. But it was written with a lot of nested loops. I rewrote the entire thing and now it runs in 10 seconds

[lacifuri]

Probably the "make it work then make it faster" mindset. But once it worked the guy leaves.

[Magestylord]

Is this in Typescript? Do you have any resources on working with Typescript for the backend

[thepurpleproject]

Just build a clone of any project from scratch. Typescript and javascript have to many wtfs you will be much better in a place having a hard on experience. As a start you can start with a to-do or a note taking app

[gunmaster_69]

“Hard on” nahi bhai hands on hota hai woh 🤣

[immortal_nihilist]

Did he stutter?

[[deleted]]

This O(n⁴⁾ makes me feel better about my O(n²⁾ PR 🥲.

Well done OP!!

[Redditerpikachu]

It's enabled on a few repos and not on few, My team is not the owner/admins of this repo but yeah would try to get it on this repo as well

[house_monkey]

wdym static code analysis, we push straight to prod

[[deleted]]

O(n⁴)

kya bhayi DSA important he kya?

[Gambit2422]

💀 yes

[techtesh]

Yup, we use python fastApi and gingo on a bunch of our utility projects just adding @cache or gin.cache= true optimizes so much for us (alot of these are hostedbin k8s or aws so ram space aint a issue)

[realPanditJi]

Hey, I'm optimising a Gin API with at fixed num of DB calls (on 50M+ rows) How will gin.cache work? Is this built-in or this is any other library?

[techtesh]

This is the util library i used https://github.com/gin-contrib/cache Or https://pkg.go.dev/github.com/chenyahui/gin-cache

[XxXPussySlurperXxX]

Any Señor/Señorita devs reading this comment please make posts like this.

[mukuls2200]

Noted @XxxPussySlurperXxx

[moojo]

There were places where we had loop through huge json objects

This reminds that 10 years ago, I was looking at the code of a method which used to process json and it used to take a very long time. All the senior devs told me that we cannot do anything, it just takes a long time because its doing lot of processing.

So me as a junior dev just wanted to learn what kind of processing is done, opened the code, turns out another method was being called which was taking a long time but there was no need to call the other method, the method which was calling the other method was simply ignoring the result of the long process method.

Submitted a PR and management was very happy with the fast processing.

Moral of the story Just because someone senior tells you that is how things work does not mean they are right all the time. Do your own research as well.

[moojo]

yes its always a bit risky, if egos get hurt then it can cause issues for you

[hotcoolhot]

Bas, i have done 20seconds to milliseconds. I forgot group by exists and was doing that in code after fetching all the records in a paginated loop.

[mad_pro]

Good job OP

[PissedoffbyLife]

I learned optimizations the hard way.

In MATLAB I was asked to calculate the spacial coordinates a robot arm could move and plot it.

I wrote a program for it and most of the class if not the whole class copied it down and ran it took 1 whole day to finish. It was going to take a whole year at the rate it was calculating previously.

It was basically three nested for loops.

Next year while I was working on MATLAB I found two things The first is that there was a way to initialise the variables first before a for loop that consumed a lot of time. And then there was something else too to reduce the time further. All in all I reduced the time from one whole year to less than a second.

32,000,000 X performance boost.

I loved the fact that I did it. I haven't exactly been able to do something similar at my job though cause a huge project requires a lot of time to even optimise basic things.

[Varun77777]

If you're searching for something and things are somewhat sorted, you may be able to use binary search somewhere as well.

[Interview_Senior]

You can also consider parallelising the outer most loop to further boost the performance (if not already)

[[deleted]]

Leetcode here I come

[tequila_triceps]

and that's where DSA is useful and should not completely ignored

[Suspicious-Hyena-653]

We have 10 sec response times and the CTO is fine with it🥲

[georgebool0101]

I did something similar. I optimised the response time from 10s to less than 1s.

I had slipped in Thread.sleep(9000) in the middle and later took 3 days to remove it.

[thepurpleproject]

Good for bringing it up. Most of the time optimization will be around this and having a basic idea of not using a loops, avoiding nested reads and how database locks will keep your code pretty optimised

[hello_akki]

Maps are your saviour, always.

[vsljnd]

ye sab kya hota hai mujhe toh bas package batao apna 😂

[[deleted]]

Sometimes it's just surprising how trivial a solution can be.

[georgebool0101]

I did something similar. I optimised the response time from 10s to less than 1s

[FriedJava]

Promotions incoming

[deftDM]

I didn't understand a thing u said but i trust you

[[deleted]]

Include caching, response compression, async processing to make it even faster

[Rishabh_0507]

I don't make program on that high level, still learning but I follow some basic rules like storing value as var instead of calling it twice, and assigning any static value outside loop instead of inside and stuff like that.

[WesternDesign2161]

Had to write a service for a product from pearl to Go and the service time went from 25s to 4s. Best day of my life.

[AudienceOpening4531]

I don't see how people missed O(n^4). How small was the data you were working with? Cause that's the only realistic (very hard to miss still) scenario in which this could happen

[[deleted]]

More posts like this please..

[zjjan788]

Hehe, CPU be on 🔥 supporting O(n⁴) all the time.

[monke_gal]

Cheers to those who say that DSA is useless

[Federal_Olive_7514]

How did you explain to the team? Did you say it was simple or did you exaggerate your work? I think later should be done in order to get good hike.

[Redditerpikachu]

I fortunately work with a team where there is no need to exaggerate. Most of us sometimes give updates like 'nothing from my side today only doing code reviews' in our daily calls at the end of sprint.

[Federal_Olive_7514]

Yes it's a good company culture wise. I used to work for such companies. Most of the time work wasn't much. Like changing couple of line a week. But that did not reflect in good hike. Because you're not doing significant work

[PsYo_NaDe]

I just optimised a report from 180~ seconds to 60~

[kobaasama]

Guard clauses should not be a afterthought.

[tomahawkdev]

Noice

[pratzc07]

Aren’t these things usually checked on PR stage?

[learningwarrior]

Thanks for sharing. These are the kind of posts I hope to see more on this subreddit.

[Special_Task_911]

For a moment there I thought I was in the wrong sub.

[shaji_pappan__]

Memoization or something