How to make it easier to identify wasted memory and identify bad scripts / applications

Hi awesome community,

In this article, I would like to share with you a small tips and tricks related to analyzing heap dump using Yourkit.

First of all, disclaimer: all things should be tested on test environment. 

 

Let's do investigation. 

1. You need to take a heap dump. Let's follow https://dzone.com/articles/how-to-capture-java-heap-dumps-7-options 

Actually, I use jcmd for take heap_dump. Because jmap is mostly affected my prod instance. ;)  Time to time JVisualVM helps to me as well.

2. Then upload to your PC. (scp, rsync, nc)

2. Let's Open snapshot 

image.png

 

3. Let's click to Class and package in Right Sidebar and check your apps just for double check. 

image.pngAnd easier you can investigate your classes and packages. Also, you can see Check which objects mostly used and wasted. 

image.png

That article helps to me https://dzone.com/articles/preventing-your-java-collections-from-wasting-memo

4. Well, let's investigate a biggest objects

image.png

 

5. Let's investigate what is this? Just click calculate GC root paths. image.png

6. Finally, it was no needed caching which was in app from marketplace.

7. Let's review "Inspections" tab. To me it is very interesting area. image.pngBecause after waiting all calculation you can find wasted data structures in your platform, app from vendor and your apps. 

8. Interesting to review your groovy scripts, maybe time to optimize. ;) 

image.png

9. Also, I found interesting app which used so much Regex. 

image.png

 

A small conlusion

0. Changed GC strategy

1. Rewrote own app 

Using that artile as start https://dzone.com/articles/preventing-your-java-collections-from-wasting-memo , I have changed the initialize the data structure values and change somewhere the data structure. e.g. Somewhere replace Hashmap into ArrayList, or with predictable init size. 

2. Noticed a few app vendors about problems. 

3. Updates to latest one or reconfigured

4. Completely removed/disabled a few apps

5. Optimized groovy scripts ( a few things was removed)

And last good thing is opening issues with integration starting so faster from 32s to ~ 6s as average. that info based on HAR files from end of users. About searching I can't provide because I don't have metrics.  VM resources I can provide also as well.

 

 

Thanks

I hope this one will be helpful for you. Next time I will share another story with other tool :)

 

Cheers,

Gonchik Tsymzhitov

3 comments

Vasil'ev Nickolay
Contributor
March 28, 2019

Sounds like a great tool! Thanks for sharing. 

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Bohdan Belokur March 29, 2019

thanks!

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Gonchik Tsymzhitov
Community Leader
Community Leader
Community Leaders are connectors, ambassadors, and mentors. On the online community, they serve as thought leaders, product experts, and moderators.
May 10, 2021

@Bohdan Belokur  @Vasil'ev Nickolay  Thank you! Do you have some stories where you can share your knowledge?

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