Will the 4GB heap size limit ever be increased?

[kayicp]

Since I want to calculate how filled is my canister’s heap memory, I need to know if I should compare rts_heap_size() divide by 4000000000 or some other variable that my canister can provide. If I have to use some other variable, what variable or function i can use to get the fixed allocated/maximum heap memory for my Motoko canister?

Thank you.

[claudio]

You probably want to divide by rts_memory_size() which is the number of Wasm memory bytes currently used by the canister (i.e. Wasm MemorySize instruction (Wasm page count) x 65536 (Wasm page size, in bytes)), currently limited by 4GiB since we are using 32-bit wasm.

Some more explanation is here:

Motoko, Array, Memory

First of all, let me point out that constructing an array by repeated concatenation is not something you should do in production code. Since both operands need to be copied for each append, the cost of doing this is quadratic in the size of the final array. Assuming you want an immutable array, a more appropriate way is to create the complete array as mutable, initialise it via mutation, and then freeze it. As for the rts values: memory_size is the current size of the Wasm memory array (mostly…

[kayicp]

Hi claudio

@claudio

currently used by the canister

@rossberg

As for the rts values: memory_size is the current size of the Wasm memory array (mostly the same as the canister memory size). This can only grow, never shrink in Wa

Thank you, claudio, for the reply. If i understand correctly, the value of rts_memory_size keeps on increasing based on how much a canister use. I did test this on Motoko Playground and keep inserting 1 million Nats, and everytime the heap_size about to reach the memory_size, the memory_size increased, which is behaving as what you guys described.

So does this mean if i want to get how filled my canister is, i should rts_heap_size divide with 4294967296. If so, then this heap size limit is fixed forever yes? Also thanks for correcting me that it’s 4 GiB, not 4GB.

[kayicp]

oh nevermind!
i found this

@akhilesh.singhania

Currently, the wasm heap is capped at 4GiB so we cannot expand it further.

So i can actually used the fixed number to check if my canister is almost filled like so:

public func isFilled() : Bool {
  return rts_heap_size() / 4294967296 * 100 > 99;
}

thanks for your time, claudio