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x/crypto/scrypt: memory not released after hash is calculated #40687

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cheng762 opened this issue Aug 11, 2020 · 2 comments
Closed

x/crypto/scrypt: memory not released after hash is calculated #40687

cheng762 opened this issue Aug 11, 2020 · 2 comments
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@cheng762
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What version of Go are you using (go version)?

$ go version
go version go1.14.1 linux/amd64

What did you do?

when I concurrent call scrypt.Key ,the memory not released after FreeOSMemory,here is the code

package main

import (
	"fmt"
	"log"
	"runtime/debug"
	"time"

	"golang.org/x/crypto/scrypt"
)

func main() {
	for i := 0; i < 30; i++ {
		go func() {
			key, _ := scrypt.Key(
				[]byte(""), // Input data.
				[]byte(""), // Salt.
				1<<18,      // Scrypt parameter N.
				16,         // Scrypt parameter r.
				1,          // Scrypt parameter p.
				64)         // Output hash length.

			fmt.Println(key)
		}()
	}

	time.Sleep(20 * time.Second)
	log.Println("free")
	debug.FreeOSMemory()

	// Keep the process running.
	time.Sleep(500 * time.Second)
}
@gopherbot gopherbot added this to the Unreleased milestone Aug 11, 2020
@davecheney
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davecheney commented Aug 11, 2020 •
edited

@cheng762 under linux we can only ask the operating system to take back memory from the processes address space, we cannot tell the operating system to do this. The operating system can, and often does, ignore this request unless it is under memory pressure from other processes.

You can verify that the scavenger ran by exporting this environment variable GODEBUG=gctrace=1 and running your process again. You will probably have to increase the amount of time to wait.

@andybons
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@davecheney is correct. Closing for now as there does not seem to be anything to do. Please feel free to comment if you feel otherwise.

@golang golang locked and limited conversation to collaborators Aug 11, 2021
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@davecheney @andybons @gopherbot @cheng762