Re: [go-nuts] For range loop variable passing by reference to go routine causes memory leak

[davy zhang]

Thank you so much for pointing this out. I didn't realize that map
won't shrink in go, that's pretty counter intuitive.

I also found the issue here:
https://github.com/golang/go/issues/20135

It looks like the right direction.

On Sun, Oct 9, 2022 at 2:29 PM wagner riffel  wrote:
>
> On 08/10/2022 22:56, davy zhang wrote:
> > Original post on stackoverflow:
> >
> > https://stackoverflow.com/questions/73985794/for-range-loop-variable-passing-by-reference-to-go-routine-causes-memory-leak
> >
> >
> > Code for reproducing the problem:
> >
> > https://go.dev/play/p/7Xzx1Aauzhh
> >
> > go version go1.19 darwin/amd64
> >
> > go tool pprof http://localhost:6060/debug/pprof/heap
> >
> > func1 is leaking
> >
> > https://i.stack.imgur.com/LTXHn.png 
> >
> > Is there any reason for this leaking?
> >
> >
> > Thank you for any input
> >
>
> I don't think it's related with for-range loops, both should "leak"
> the same, I bet that's tMap, currently in Go maps do not shrink, even
> if you delete keys. One way to reduce memory usage of a long-living
> map is to at some threshold copy over all its elements into a new map,
> and set the old to map to this copy, then the old map, if not
> referenced elsewhere, will eventually be gc'ed and cleaned up.
>
> -w
>

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Re: [go-nuts] For range loop variable passing by reference to go routine causes memory leak

['wagner riffel' via golang-nuts]

On 08/10/2022 22:56, davy zhang wrote:

Original post on stackoverflow:

https://stackoverflow.com/questions/73985794/for-range-loop-variable-passing-by-reference-to-go-routine-causes-memory-leak


Code for reproducing the problem:

https://go.dev/play/p/7Xzx1Aauzhh

go version go1.19 darwin/amd64

go tool pprof http://localhost:6060/debug/pprof/heap

func1 is leaking

https://i.stack.imgur.com/LTXHn.png 

Is there any reason for this leaking?


Thank you for any input



I don't think it's related with for-range loops, both should "leak"
the same, I bet that's tMap, currently in Go maps do not shrink, even
if you delete keys. One way to reduce memory usage of a long-living
map is to at some threshold copy over all its elements into a new map,
and set the old to map to this copy, then the old map, if not
referenced elsewhere, will eventually be gc'ed and cleaned up.

-w

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[go-nuts] For range loop variable passing by reference to go routine causes memory leak

[davy zhang]

Original post on stackoverflow:

https://stackoverflow.com/questions/73985794/for-range-loop-variable-passing-by-reference-to-go-routine-causes-memory-leak


Code for reproducing the problem: 

https://go.dev/play/p/7Xzx1Aauzhh

go version go1.19 darwin/amd64

go tool pprof http://localhost:6060/debug/pprof/heap

func1 is leaking

https://i.stack.imgur.com/LTXHn.png

Is there any reason for this leaking?


Thank you for any input


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