Memory Playgrounds

Goal of these two programs is to allocate memory and free it in various ways. C version is making a rough attempt to allocate and de-allocate in a similar way to the go runtime.

Modes

There are 2 modes that this program operates in.

Interactive

The default (ie, without arguments) is to run in "interactive" mode. This version starts and waits for keyboard input.

See the printed help messages for the commands accepted.

Up-front

There are 3 arguments taken via env var, and each must be specified and valid in order for the program to run in "up-front" mode.

• NUM_ALLOCS - (int) - The number of allocations to perform of the given size
• ALLOC_SIZE - (int) - The number of bytes to request during each allocation
• INITIAL_SLEEP - (int) - The number of seconds to sleep before allocating anything. This can be useful to determine a "baseline" for the process.

Both the C and Go version take the same arguments.

C Usage

Build

cd c_version
make
./cmadv

Run via docker

# To run in interactive mode
docker run --rm -it ghcr.io/scottopell/madv:c-latest

# To run in up-front mode
docker run --rm -e ALLOC_SIZE=10000000 -e NUM_ALLOCS=5 -e INITIAL_SLEEP=5 ghcr.io/scottopell/madv:c-latest

Go Usage

Build

cd go_version
go build -o gomadv main.go
./gomadv

Run via docker

# To run in interactive mode
docker run --rm -it ghcr.io/scottopell/madv:c-latest

# To run in up-front mode
docker run --rm -e ALLOC_SIZE=10000000 -e NUM_ALLOCS=5 -e INITIAL_SLEEP=5 ghcr.io/scottopell/madv:go-latest

Results

To "view the results" the idea is to check the OS level RSS reported.

hwatch 'ps e -o "rss,vsz,pid" -p $(pidof gomadv)'

In the C version, a free operation appears to be pretty immediate and correctly reduces the RSS.

In the Go version, the RSS goes down immediately post FreeOsMemory. It seems to take ~1min for the scavenger to return the memory otherwise.