That’s the interim solution I am using right now (manually precompiling most
functions), but I generate quite a lot of closures dynamically in my code and
the potential performance loss is a bit worrying… I don’t think the current
behavior is expected based on what the documentation says.
Cheers,
Taras
> On 18 Aug 2021, at 16:36, Duncan Murdoch <murdoch.dun...@gmail.com> wrote:
>
> Forgot to add: you could define f_env like this to get it compiled:
>
> f_env <- local({
> cmpfun(function(x) {
> for(i in 1:10000) x <- x + 1
> x
> })
> })
>
> Not as convenient as JIT, but it gets the job done...
>
> Duncan Murdoch
>
> On 18/08/2021 10:33 a.m., Duncan Murdoch wrote:
>> On 18/08/2021 9:00 a.m., Taras Zakharko wrote:
>>> I have encountered a behavior of R’s JIT compiler that I can’t quite figure
>>> out. Consider the following code:
>>>
>>>
>>> f_global <- function(x) {
>>> for(i in 1:10000) x <- x + 1
>>> x
>>> }
>>>
>>> f_env <- local({
>>> function(x) {
>>> for(i in 1:10000) x <- x + 1
>>> x
>>> }
>>> })
>>>
>>> compiler::enableJIT(3)
>>>
>>> bench::mark(f_global(0), f_env(0))
>>> # 1 f_global(0) 103µs 107.61µs 8770. 11.4KB 0 4384 0
>>> # 2 f_env(0) 1.1ms 1.42ms 712. 0B 66.3 290 27
>>> Inspecting the closures shows that f_global has been byte-compiled while
>>> f_env has not been byte-compiled. Furthermore, if I assign a new
>>> environment to f_global (e.g. via environment(f_global) <- new.env()), it
>>> won’t be byte-compiled either.
>>>
>>> However, if I have a function returning a closure, that closure does get
>>> byte-compiled:
>>>
>>> f_closure <- (function() {
>>> function(x) {
>>> for(i in 1:10000) x <- x + 1
>>> x
>>> }
>>> })()
>>>
>>> bench::mark(f_closure(0))
>>> # 1 f_closure(0) 105µs 109µs 8625. 0B 2.01 4284
>>> 1 497ms
>>>
>>> What is going on here? Both f_closure and f_env have non-global
>>> environments. Why is one JIT-compiled, but not the other? Is there a way to
>>> ensure that functions defined in environments will be JIT-compiled?
>> About what is going on in f_closure: I think the anonymous factory
>> function() {
>> function(x) {
>> for(i in 1:10000) x <- x + 1
>> x
>> }
>> }
>> got byte compiled before first use, and that compiled its result. That
>> seems to be what this code indicates:
>> f_closure <- (function() {
>> res <- function(x) {
>> for(i in 1:10000) x <- x + 1
>> x
>> }; print(res); res
>> })()
>> #> function(x) {
>> #> for(i in 1:10000) x <- x + 1
>> #> x
>> #> }
>> #> <bytecode: 0x7fb43ec3aa70>
>> #> <environment: 0x7fb441117ac0>
>> But even if that's true, it doesn't address the bigger question of why
>> f_global and f_env are treated differently.
>> Duncan Murdoch
>
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