A tool for creating subsecond offset heatmaps for ICMP echo (ping) replies
I noticed that occasionally my MacBook Pro's wifi latency would become spiky. It was most noticeable when I was using interactive sessions like SSH, but it was degrading my download throughput too. Using ICMP echo (ping) requests and plotting their response time on a subsecond offset heatmap, I could visualize the latency and confirm that it spiked from ~5ms to ~300ms (or more) every half second. I eventually traced it to a specific VirtualBox VM. In the process, this tool was born.
Most of the interesting bits happen in the pinger module, which continuously sends ICMP echo packets to a host with a frequency that you specify. When the responses arrive, the pinger records the timestamp and the delay (latency), and then that data is sent to the dataPointPartitioner to be divided into one-second buckets. Those buckets are then displayed as a heatmap.
Visually, it's important to understand that both axes are displaying time. The x-axis shows a rolling window of passing time, which is common, but the y-axis shows the latency at various points within each second. If you're dealing with a problem that occurs very briefly and/or more frequently than once per second, as I was, then this extra resolution is critical.
If you have the Go toolchain installed, go get should work:
go get -u github.com/acj/pingrok
Clone this repository, and then:
go build
and optionally:
go test ./...
This has been tested on a Linux host but may have issues in other environments like Docker for Mac.
sudo docker build -f docker/Dockerfile -t pingrok .
sudo docker run --network=host --rm -it pingrok [options]
$ ./pingrok --help
Usage of ./pingrok:
-h string
the host to ping (default "192.168.1.1")
-l string
Log file path (default "pingrok.log")
-o Overlay latency numbers on heatmap
-r int
number of pings per second (default 10)
-t int
seconds of data to display (default 30)