sqlite3_busy_timeout.rb

require 'bundler/inline'
require "thread"
require "tempfile"

gemfile do
  source 'https://rubygems.org'
  gem 'sqlite3', '1.3.13'
  gem 'pry'
end

puts 'Gems installed and loaded!'
puts "The SQLite3 version #{SQLite3::SQLITE_VERSION}"

begin
  database_path = Tempfile.open("testdb")
  db = SQLite3::Database.new(database_path.path)
  db.transaction do
    db.execute("CREATE TABLE `test_1` (connection_role VARCHAR (255))")
    db.execute("INSERT INTO test_1 VALUES ('main-1')")
  end

  thread = Thread.new do
    begin
      thread_db = SQLite3::Database.new(database_path.path)
      thread_db.transaction(:immediate) do
        puts "puts:bg:1 #{thread_db.execute("SELECT * FROM test_1")}"
        thread_db.execute("INSERT INTO test_1 VALUES ('bg-1')")
        puts "puts:bg:2 #{thread_db.execute("SELECT * FROM test_1")}"
        sleep 2
        thread_db.execute("INSERT INTO test_1 VALUES ('bg-2')")
        puts "puts:bg:3 #{thread_db.execute("SELECT * FROM test_1")}"
      end
      puts "puts:bg:4 transaction closed"
    ensure
      thread_db.close if thread_db
    end
  end

  puts "puts:main:1 #{db.execute("SELECT * FROM test_1")}"

  sleep 1

  puts "puts:main:2 #{db.execute("SELECT * FROM test_1")}"

  db.busy_timeout 3000 # <-- raises: .rbenv/versions/2.6.1/lib/ruby/gems/2.6.0/gems/sqlite3-1.3.13/lib/sqlite3/statement.rb:108:in `step': database is locked (SQLite3::BusyException)

  # busy_handler works as expected
  # db.busy_handler do
  #   true
  # end

  puts "puts:main:3 #{db.execute("SELECT * FROM test_1")}"

  db.execute("INSERT INTO test_1 VALUES ('main-2')")

  puts "puts:main:4 #{db.execute("SELECT * FROM test_1")}"

  thread.join
ensure
  database_path.close
  database_path.unlink
end