Home » Software Development » Wasting time by saving memory

About Peter Lawrey

Peter Lawrey

Wasting time by saving memory

You might say that at my company, the hard ware is 10x more expensive, but it also likely you time is costing the company about the same more.

In any case, this article attempts to demonstate that there is a tipping point where it no longer makes sense to spend time saving memory, or even thinking about it.

a screen refresh
20 ms
      27 KB150 bytes       1 MB  24 KB
one trivial change
~1 sec
     1.4 MB  7.6 KB     60 MB    1.2 MB
one command
~5 sec
        7 MB  50 KB   400 MB    6 MB
a line of code
~1 min
      84 MB 460 KB  3,600 MB  72 MB
a small change
~20 min
  1600 MB    9 MB72,000 MB    1.4 GB
a significant change
~1 day
       40 GB  0.2 GB  1,700 GB  35 GB
a major change
~2 weeks
      390 GB  2 GB17,000 GB 340 GB

Your mileage may vary, but just today some one asked how to save a few bytes by passing short instead of int as method arguments (Java doesn’t save any memory if you do) Even if it did save as much as it might, the time taken to ask the question, let alone implement and test it, could have been worth 10,000,000 times the cost of memory it could have saved.

In short; don’t fall into the trap of a mind boggling imbalance of scale.

Reference: Wasting time by saving memory from our JCG partner Peter Lawrey at the Vanilla Java blog.

(0 rating, 0 votes)
You need to be a registered member to rate this.
4 Comments Views Tweet it!
Do you want to know how to develop your skillset to become a Java Rockstar?
Subscribe to our newsletter to start Rocking right now!
To get you started we give you our best selling eBooks for FREE!
1. JPA Mini Book
2. JVM Troubleshooting Guide
3. JUnit Tutorial for Unit Testing
4. Java Annotations Tutorial
5. Java Interview Questions
6. Spring Interview Questions
7. Android UI Design
and many more ....
I agree to the Terms and Privacy Policy

Leave a Reply

4 Comment threads
0 Thread replies
Most reacted comment
Hottest comment thread
4 Comment authors
KelvinkgSamTom WAn0nym0usC0ward Recent comment authors

This site uses Akismet to reduce spam. Learn how your comment data is processed.

newest oldest most voted
Notify of

It all depends. If you absolutely need to run your code on a mem-constrained machine, or your code will run in ten million instances (for example being run on ten million mobile phones), spending a day to save a kilobyte might be time well spent.

Tom W

Yes, it’s amazing how people (even in the software industry) waste time worrying about bytes, on big systems perfectly able to handle the data.

I’ve seen such focus on the trivial add tens of thousands of dollars in costs, and get designs wrong. Normally for decent-sized hardware the metric should be “cost of integration” & “cost of future adaptability/ maintenance”, low-level metrics emphasize the wrong design goals.


So you call this paragraph an article ! Great


Do you have experience on supporting a real production system?
If all members in a team don’t have such a mindset of resourse usage, including memorry, the system would be great…..