Garbage collection unexpected results

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•

charlie in reply to @Gordon

So it's 8x slower than just using an Array, and honestly I'm amazed
it's that good.

At first I did just use an array but I need to limit the size otherwise the mem is very quickly consumed (think wanting to sample gps data, but only recent as you want to reduce noise). You are speed testing two different things. You are saying pushing to an array is quicker than pushing to an array and then pruning it. Which is obviously true. If you have a quicker way of pushing and then resizing that would be more constructive.

On Espruino as far as I can see you could just use Array directly, and
if you really need to limit the size of the queue you could override
.push to just call splice after it to limit the length.

I am literally doing the same thing as splice after push (via shift). Originally I extended Array rather than having an internal array variable but the espruino compiler isn't releasing memory when splice or shift.

I mean, you look at isEmpty, it's calling this.any() which calls
_this.length which is a getter which calls this.internalArray.length. It's just a nightmare - it's like someone wrote the code specifically
to waste CPU cycles - even on Node.js it's going to suck
If I want to know if my array is empty I need to do a check in my code. I still need to call array.length. I could repeat this code every time I want to check, it wouldn't speed up the processing, or I can add an additional layer which can be individually unit tested and optimised further in future.

Ultimately you might save some cpu time with large chunks of repeated code. It will limit you from creating good stable apps which are easy to maintain and extend. Most of the apps in the current app library are not extendable or maintainable. You need to be able to split the code into small segments to unit test. Otherwise you are taking a step back to pre object orientated test driven development.

•

fanoush in reply to @charlie

but the espruino compiler isn't releasing memory when splice or shift.

it is interpreter, compilers are supposed to compile, not manage runtime memory

Just tried slice, splice, shift and also pop, at least in simple cases it works


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>a=[];i=0
=0
>process.memory()
={ free: 13978, usage: 22, total: 14000, history: 9,
  gc: 0, gctime: 2.469, blocksize: 18 }
>for (var i=0;i<100;i++)a.push(i)
=undefined
>process.memory()
={ free: 13878, usage: 122, total: 14000, history: 13,
  gc: 0, gctime: 2.435, blocksize: 18 }
>while(a.length)a.shift()
=undefined
>process.memory()
={ free: 13978, usage: 22, total: 14000, history: 16,
  gc: 0, gctime: 1.872, blocksize: 18 }
>for (var i=0;i<100;i++)a.push(i)
=undefined
>process.memory()
={ free: 13878, usage: 122, total: 14000, history: 16,
  gc: 0, gctime: 1.664, blocksize: 18 }
>for (i=0;i<100;i++)a.push(i)
=undefined
>process.memory()
={ free: 13778, usage: 222, total: 14000, history: 20,
  gc: 0, gctime: 0.697, blocksize: 18 }
>while(a.length)a.shift()
=undefined
>process.memory()
={ free: 13978, usage: 22, total: 14000, history: 20,
  gc: 0, gctime: 2.424, blocksize: 18 }
>for (i=0;i<100;i++)a.push(i)
=undefined
>process.memory()
={ free: 13878, usage: 122, total: 14000, history: 20,
  gc: 0, gctime: 2.41, blocksize: 18 }
>while(a.length)a.pop()
=undefined
>process.memory()
={ free: 13978, usage: 22, total: 14000, history: 23,
  gc: 0, gctime: 0.525, blocksize: 18 }
>for (i=0;i<100;i++)a.push(i)
=undefined
>a=a.slice(50)
=[ 50, 51, 52, 53, 54,  ... 95, 96, 97, 98, 99 ]
>process.memory()
={ free: 13928, usage: 72, total: 14000, history: 25,
  gc: 0, gctime: 0.528, blocksize: 18 }
>while(a.length)a.pop()
=undefined
>process.memory()
={ free: 13978, usage: 22, total: 14000, history: 25,
  gc: 0, gctime: 0.687, blocksize: 18 }
>
>a=[1,2,3,4,5]
=[ 1, 2, 3, 4, 5 ]
>process.memory()
={ free: 13973, usage: 27, total: 14000, history: 30,
  gc: 0, gctime: 0.812, blocksize: 18 }
>a.splice(3,2,10,11)
=[ 4, 5 ]
>a
=[ 1, 2, 3, 10, 11 ]
>process.memory()
={ free: 13973, usage: 27, total: 14000, history: 30,
  gc: 0, gctime: 2.526, blocksize: 18 }
>a.splice(3,2)
=[ 10, 11 ]
>process.memory()
={ free: 13975, usage: 25, total: 14000, history: 34,
  gc: 0, gctime: 2.294, blocksize: 18 }
>a
=[ 1, 2, 3 ]
>

check usage, goes up and down as expected

It will limit you from creating good stable apps

For me good and stable app is not bloated app that runs slow (=drains more battery) and needs lot of memory.

which are easy to maintain and extend. Most of the apps in the current app library are not extendable or maintainable.

This is debatable. Smaller code without unneeded abstractions can be easy to maintain and extend too. Someone else may see your perfectly testable and extensible code hard too. Also the size of typical watch app is not that big and people write it for fun and for free so extendable and maintainable may not be even the goal here.

Garbage collection unexpected results

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