tonyc

Using strace and lsof to debug blocked processes

You can use strace on a specific pid to figure out what a specific process is doing, e.g.:

strace -fp <pid>

You might see something like:

select(9, [3 5 8], [], [], {0, 999999}) = 0 (Timeout)

tonyc

defmodule App.Service do

  @spec parse() :: {:ok, String.t()}, | {:error, String.t()}
  def parse do
    url = "https://example.com/foo.txt"
    
    case HTTPoison.get(url) do
      {:ok, %HTTPoison.response{status_code: 200, body: body}} ->
        body   # Note: Not {:ok, body}
      _ ->

tonyc

function lb() {
  local_bundle_ver=$(grep -A1 "BUNDLED WITH" Gemfile.lock | grep -v BUNDLED | tr -d '[:space:]')

  if [ -n "$local_bundle_ver" ]; then
    echo "Using bundler ${local_bundle_ver}"
    bundle _${local_bundle_ver}_ $*
  else
    echo "Could not determine correct version of bundler to use. Sorry!"
  fi
}

tonyc

function local_bundle() {
  local_bundle_ver=$(grep -A1 "BUNDLED WITH" Gemfile.lock | grep -v BUNDLED | tr -d '[:space:]')
  if [ -n "$local_bundle_ver" ]; then
    echo "Using bundler ${local_bundle_ver}"
    bundle _${local_bundle_ver}_ $*
  else
    echo "Could not determine correct version of bundler to use. Sorry!"
  fi
}

tonyc

          ___
        /\__  _\/\ \      __            /\__  _\            /\  _  \
        \/_/\ \/\ \ \___ /\_\    ____   \/_/\ \/     ____   \ \ \L\ \
           \ \ \ \ \  _ `\/\ \  /',__\     \ \ \    /',__\   \ \  __ \
            \ \ \ \ \ \ \ \ \ \/\__, `\     \_\ \__/\__, `\   \ \ \/\ \
             \ \_\ \ \_\ \_\ \_\/\____/     /\_____\/\____/    \ \_\ \_\
              \/_/  \/_/\/_/\/_/\/___/      \/_____/\/___/      \/_/\/_/

                                               ____    __
       /'\_/`\                  __            /\  _`\ /\ \

tonyc

iex(30)> flush
{:circuits_uart, "ttyACM0", "BY 0,1"}
{:circuits_uart, "ttyACM0", "BY 0,0"}
:ok
iex(31)> flush
{:circuits_uart, "ttyACM0", "FQ 0,0146985000"}
{:circuits_uart, "ttyACM0", "FQ 0,0147030000"}
{:circuits_uart, "ttyACM0", "FQ 0,0147060000"}
{:circuits_uart, "ttyACM0", "FQ 0,0147120000"}
{:circuits_uart, "ttyACM0", "FQ 0,0147165000"}

tonyc

iex(8)> flush
{:circuits_uart, "ttyACM0", "$GPRMC,,V,,,,,,,,,,N*53\r\n"}
{:circuits_uart, "ttyACM0", "$GPGGA,,,,,,0,,,,,,,,*66\r\n"}
{:circuits_uart, "ttyACM0", "$GPRMC,,V,,,,,,,,,,N*53\r\n"}
{:circuits_uart, "ttyACM0", "$GPGGA,,,,,,0,,,,,,,,*66\r\n"}
{:circuits_uart, "ttyACM0", "$GPRMC,,V,,,,,,,,,,N*53\r\n"}
{:circuits_uart, "ttyACM0", "$GPGGA,,,,,,0,,,,,,,,*66\r\n"}
{:circuits_uart, "ttyACM0", "$$CRC6CCE,W8SXT>API510,DSTAR*:"}
{:circuits_uart, "ttyACM0", "$GPRMC,,V,,,,,,,,,,N*53\r\n"}
{:circuits_uart, "ttyACM0", "$GPGGA,,,,,,0,,,,,,,,*66\r\n"}

tonyc

iex(3)> Nerves.UART.enumerate()
%{
  "ttyACM0" => %{
    description: "TH-D74",
    manufacturer: "JVC KENWOOD",
    product_id: 24587,
    vendor_id: 8550
  },
  "ttyS0" => %{}
}

tonyc

#!/usr/bin/env bash

set -e

BASE_DIR="${HOME}/Pictures/uploads"
BUCKET="your-s3-bucket-name"

FILENAME=$(uuidgen).png
FULL_PATH="${BASE_DIR}/${FILENAME}"

tonyc

#!/usr/bin/env bash

get_latest_sha () {
  heroku releases --num 1 --remote $1 2> /dev/null | grep -v === | awk '{print $3}'
}

STAGING_SHA=$(get_latest_sha "staging")
PRODUCTION_SHA=$(get_latest_sha "production")

echo "Staging: $STAGING_SHA, Production: $PRODUCTION_SHA"