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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.
 
 
 
 
 
 
 

time
spent
cheap
memory
expensive
memory
cheap
disk
expensive
disk
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.

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3 comments

  1. 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.

  2. 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.

  3. So you call this paragraph an article ! Great

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