pandora

README

Pandora

A load generator in Go language.

How to start

Binary releases

Download available.

Building from sources

We use glide for package management. Install it before compiling Pandora Compile a binary with go tool (use go >= 1.8):

go get github.com/yandex/pandora
cd $GOPATH/src/github.com/yandex/pandora
glide install
go build

You can also cross-compile for other arch/os:

GOOS=linux GOARCH=amd64 go build

Running your tests

Run the binary with your config (see config examples at examples):

# $GOBIN should be added to $PATH
pandora myconfig.yaml

Or use Pandora with Yandex.Tank and Overload.

Example

load.yaml:

pools:
  - id: HTTP pool                    # Pool name
    gun:
      type: http                     # Gun type
      target: example.com:80         # Gun target
    ammo:
      type: uri                      # Ammo format                        
      file: ./ammo.uri               # Ammo File
    result:
      type: phout                    # Report format (phout is for Yandex.Tank)
      destination: ./phout.log  # Report file name

    rps:                             # RPS Schedule
      type: periodic                 # shoot periodically
      period: 0.1s                   # ten batches each second
      max: 30                        # thirty batches total
      batch: 2                       # in batches of two shoots

    startup:                         # Startup Schedule
      type: periodic                 # start Instances periodically
      period: 0.5s                   # every 0.5 seconds
      batch: 1                       # one Instance at a time
      max: 5                         # five Instances total

ammo.uri:

/my/first/url
/my/second/url

Run your tests:

pandora load.yaml

The results are in phout.log. Use Yandex.Tank and Overload to plot them.

Basic concepts

Architectural scheme

See architectural scheme source in docs/architecture.graphml. It was created with YeD editor.

Pandora is a set of components talking to each other through the channels. There are different types of components.

Component types

Ammo Provider

Ammo Provider knows how to make an ammo object from an ammo file or other external resource. Instances get ammo objects from Ammo Provider.

Instances Pool

Instances Pool manages the creation of Instances. You can think of one Instance as a single user that sends requests to a server sequentially. All Instances from one Instances Pool get their ammo from one Ammo Provider. Instances creation times are controlled by Startup Scheduler. All Instances from one Instances Pool also have Guns of the same type.

Scheduler

Scheduler controls other events' times by pushing messages to its underlying channel according to the Schedule. It can control Instances startup times, RPS amount (requests per second) or other processes.

By combining two types of Schedulers, RPS Scheduler and Instance Startup Scheduler, you can simulate different types of load. Instace Startup Scheduler controls the level of parallelism and RPS Scheduler controls throughput.

If you set RPS Scheduler to 'unlimited' and then gradually raise the number of Instances in your system by using Instance Startup Scheduler, you'll be able to study the scalability of your service.

If you set Instances count to a big, unchanged value (you can estimate the needed amount by using Little's Law) and then gradually raise the RPS by using RPS Scheduler, you'll be able to simulate Internet and push your service to its limits.

You can also combine two methods mentioned above. And, one more thing, RPS Scheduler can control a whole Instances Pool or each Instance individually.

Schedule types

periodic

Shoot in batches with fixed intervals. Parameters:

• period – interval between batches, example: 0.1s – 10 batches in a second
• batch – batch size, default: 1
• max – total number of batches, default: unlimited

linear

RPS (requests per second) will grow linearly during test.

• duration – schedule part duration
• start-rps – RPS on the left side of the schedule
• end-rps – RPS on the right side of the schedule

unlimited

Produces ticks without any limits.

Instances and Guns

Instances takes an ammo, waits for a Scheduler tick and then shoots with a Gun it has. Gun is a tool that sends a request to your service and measures the parameters (time, error codes, etc.) of the response.

Aggregator

Aggregator collects measured samples and saves them somewhere.