posener

Be Careful with Table Driven Tests and t.Parallel()

We Gophers, love table-driven-tests, it makes our unittesting structured, and makes it easy to add different test cases with ease.

Let’s create our table driven test, for convenience, I chose to use t.Log as the test function. Notice that we don't have any assertion in this test, it is not needed to for the demonstration.

func TestTLog(t *testing.T) {
	t.Parallel()

bobrik

Overly aggressive CFS

We're looking at CPU bandwidth control via CFS:

• https://www.kernel.org/doc/Documentation/scheduler/sched-bwc.txt

Reproduction program

Program does number of iterations, in each iteration we burn CPU in small chunks until we get 5ms of real time spent. On each iteration we also print how much

siddharthkp

This proposal is not longer active. Context: https://twitter.com/siddharthkp/status/909818777314902016

---

kamilhristov

apiVersion: kops/v1alpha2
kind: Cluster
metadata:
  name: kube.kamilhristov.com
spec:
  cloudProvider: aws
  etcdClusters:
  - etcdMembers:
    - instanceGroup: master-1
      name: master-1

kizbitz

#!/bin/bash

# Example for the Docker Hub V2 API
# Returns all images and tags associated with a Docker Hub organization account.
# Requires 'jq': https://stedolan.github.io/jq/

# set username, password, and organization
UNAME=""
UPASS=""
ORG=""

jboner

Latency Comparison Numbers (~2012)
----------------------------------
L1 cache reference                           0.5 ns
Branch mispredict                            5   ns
L2 cache reference                           7   ns                      14x L1 cache
Mutex lock/unlock                           25   ns
Main memory reference                      100   ns                      20x L2 cache, 200x L1 cache
Compress 1K bytes with Zippy             3,000   ns        3 us
Send 1K bytes over 1 Gbps network       10,000   ns       10 us
Read 4K randomly from SSD*             150,000   ns      150 us          ~1GB/sec SSD