Techniques for investigating untypical Go memory leaks(cossacklabs.com)
cossacklabs.com
Techniques for investigating untypical Go memory leaks
https://www.cossacklabs.com/blog/investigating-go-memory-leaks.html
9 comments
May not have been a "decision" at all. The simplest GC just needs to hijack malloc to keep track of allocations and every now and then scan the process memory for values that look like pointers into those allocations. Of course that is both slow and leaks bad enough that early Go versions had issues with 32bit address space.
Well, it is true: it was interesting side effect that 'just worked', we were like 'hmm, if GC is able to control external memory allocation, well, fine, maybe Go is even better than we've thought initially'.
At some point in time, someone behind Go/CGo realized that automatically managing pointer math is an exercise that is being attempted for last 15 years without success (there always will be absolutely normal situations where you can't measure allocation correctly), and just limited visibility scope to things Go can control.
"This looks like a serious API break."
So thought we, being a bit annoyed. But when you think of how many problems it actually prevents,- it's a worthy move, in the end.
At some point in time, someone behind Go/CGo realized that automatically managing pointer math is an exercise that is being attempted for last 15 years without success (there always will be absolutely normal situations where you can't measure allocation correctly), and just limited visibility scope to things Go can control.
"This looks like a serious API break."
So thought we, being a bit annoyed. But when you think of how many problems it actually prevents,- it's a worthy move, in the end.
"var output = (*byte)(unsafe.Pointer(m))" This will give you the pointer to the byte slice object which may have its own structure which is opaque to you and this is not same as "getting the pointer to C byte array". It is weird that it was producing correct results at all :)
Techniques for noticing you're almost shooting yourself in the leg, then suddenly saving the situation very last moment, mi amigo :)
This remember me one of the Go Proverbs, Cgo is not Go https://www.youtube.com/watch?v=PAAkCSZUG1c&t=12m37s
But, as he says, 'sometimes you have to'. This is a time like this.
This looks like a serious API break.
To be fair, the whole idea of the runtime automagically managing external memory gives me shivers, and this looks like moving in the right direction - I just think it was not very wise to go with that initial decision in the first place.