使用Ruby可以写出简短而又功能强大的代码
下面的方法用来完成两个矩阵的乘积
def matrix_mul(matrix1,matrix2)
result=[]
(0...matrix1.length).each{|i|
temp=[]
(0...matrix2[0].length).each{|j|
tmp=0
(0...matrix1[0].length).each{|k|
tmp+=matrix1[i][k]*matrix2[k][j]
}
temp<<tmp
}
result<<temp
}
return result
end
注：ruby标准库中已包含矩阵库 Matrix
Ruby 多线程
# 线程 #1 代码部分
Thread.new {
# 线程 #2 执行代码
}
# 线程 #1 执行代码
实例
以下实例展示了如何在Ruby程序中使用多线程：
#!/usr/bin/ruby
def func1
i=0
while i<=2
puts "func1 at: #{Time.now}"
sleep(2)
i=i+1
end
end
def func2
j=0
while j<=2
puts "func2 at: #{Time.now}"
sleep(1)
j=j+1
end
end
puts "Started At #{Time.now}"
t1=Thread.new{func1()}
t2=Thread.new{func2()}
t1.join
t2.join
puts "End at #{Time.now}"
Started At Wed May 14 08:21:54 -0700 2014
func1 at: Wed May 14 08:21:54 -0700 2014
func2 at: Wed May 14 08:21:54 -0700 2014
func2 at: Wed May 14 08:21:55 -0700 2014
func1 at: Wed May 14 08:21:56 -0700 2014
func2 at: Wed May 14 08:21:56 -0700 2014
func1 at: Wed May 14 08:21:58 -0700 2014
End at Wed May 14 08:22:00 -0700 2014
线程状态
线程有5种状态：
| 线程状态 | 返回值 |
|---|---|
| Runnable | run |
| Sleeping | Sleeping |
| Aborting | aborting |
| Terminated normally | false |
| Terminated with exception | nil |
begin
t = Thread.new do
Thread.pass # 主线程确实在等join
raise "unhandled exception"
end
t.join
rescue
p $! # => "unhandled exception"
end
通过Mutex类实现线程同步
通过Mutex类实现线程同步控制，如果在多个线程钟同时需要一个程序变量，可以将这个变量部分使用lock锁定。 代码如下：
#encoding:gbk
require "thread"
puts "Synchronize Thread"
@num=200
@mutex=Mutex.new
def buyTicket(num)
@mutex.lock
if @num>=num
@num=@num-num
puts "you have successfully bought #{num} tickets"
else
puts "sorry,no enough tickets"
end
@mutex.unlock
end
ticket1=Thread.new 10 do
10.times do |value|
ticketNum=15
buyTicket(ticketNum)
sleep 0.01
end
end
ticket2=Thread.new 10 do
10.times do |value|
ticketNum=20
buyTicket(ticketNum)
sleep 0.01
end
end
sleep 1
ticket1.join
ticket2.join
Synchronize Thread
you have successfully bought 15 tickets
you have successfully bought 20 tickets
you have successfully bought 15 tickets
you have successfully bought 20 tickets
you have successfully bought 15 tickets
you have successfully bought 20 tickets
you have successfully bought 15 tickets
you have successfully bought 20 tickets
you have successfully bought 15 tickets
you have successfully bought 20 tickets
you have successfully bought 15 tickets
sorry,no enough tickets
sorry,no enough tickets
sorry,no enough tickets
sorry,no enough tickets
sorry,no enough tickets
sorry,no enough tickets
sorry,no enough tickets
sorry,no enough tickets
sorry,no enough tickets
除了使用lock锁定变量，还可以使用try_lock锁定变量，还可以使用Mutex.synchronize同步对某一个变量的访问。
监管数据交接的Queue类实现线程同步
Queue类就是表示一个支持线程的队列，能够同步对队列末尾进行访问。不同的线程可以使用统一个对类，但是不用担心这个队列中的数据是否能够同步，另外使用SizedQueue类能够限制队列的长度
SizedQueue类能够非常便捷的帮助我们开发线程同步的应用程序，应为只要加入到这个队列中，就不用关心线程的同步问题。
经典的生产者消费者问题：
#!/usr/bin/ruby
require "thread"
puts "SizedQuee Test"
queue = Queue.new
producer = Thread.new do
10.times do |i|
sleep rand(i) # 让线程睡眠一段时间
queue << i
puts "#{i} produced"
end
end
consumer = Thread.new do
10.times do |i|
value = queue.pop
sleep rand(i/2)
puts "consumed #{value}"
end
end
consumer.join
SizedQuee Test
0 produced
1 produced
consumed 0
2 produced
consumed 1
consumed 2
3 produced
consumed 34 produced
consumed 4
5 produced
consumed 5
6 produced
consumed 6
7 produced
consumed 7
8 produced
9 produced
consumed 8
consumed 9
#!/usr/bin/ruby
count = 0
arr = []
10.times do |i|
arr[i] = Thread.new {
sleep(rand(0)/10.0)
Thread.current["mycount"] = count
count += 1
}
end
arr.each {|t| t.join; print t["mycount"], ", " }
puts "count = #{count}"
8, 0, 3, 7, 2, 1, 6, 5, 4, 9, count = 10
线程优先级
线程的优先级是影响线程的调度的主要因素。其他因素包括占用CPU的执行时间长短，线程分组调度等等。
可以使用 Thread.priority 方法得到线程的优先级和使用 Thread.priority= 方法来调整线程的优先级。
线程的优先级默认为 0 。 优先级较高的执行的要快。
一个 Thread 可以访问自己作用域内的所有数据，但如果有需要在某个线程内访问其他线程的数据应该怎么做呢？ Thread 类提供了线程数据互相访问的方法，你可以简单的把一个线程作为一个 Hash 表，可以在任何线程内使用 []= 写入数据，使用 [] 读出数据。
athr = Thread.new { Thread.current["name"] = "Thread A"; Thread.stop }
bthr = Thread.new { Thread.current["name"] = "Thread B"; Thread.stop }
cthr = Thread.new { Thread.current["name"] = "Thread C"; Thread.stop }
Thread.list.each {|x| puts "#{x.inspect}: #{x["name"]}" }
可以看到，把线程作为一个 Hash 表，使用 [] 和 []= 方法，我们实现了线程之间的数据共享。
线程互斥
Mutex(Mutal Exclusion = 互斥锁)是一种用于多线程编程中，防止两条线程同时对同一公共资源（比如全局变量）进行读写的机制。
不使用Mutax的实例
#!/usr/bin/ruby
require 'thread'
count1 = count2 = 0
difference = 0
counter = Thread.new do
loop do
count1 += 1
count2 += 1
end
end
spy = Thread.new do
loop do
difference += (count1 - count2).abs
end
end
sleep 1
puts "count1 : #{count1}"
puts "count2 : #{count2}"
puts "difference : #{difference}"
count1 : 9712487
count2 : 12501239
difference : 0
使用Mutax的实例
#!/usr/bin/ruby
require 'thread'
mutex = Mutex.new
count1 = count2 = 0
difference = 0
counter = Thread.new do
loop do
mutex.synchronize do
count1 += 1
count2 += 1
end
end
end
spy = Thread.new do
loop do
mutex.synchronize do
difference += (count1 - count2).abs
end
end
end
sleep 1
mutex.lock
puts "count1 : #{count1}"
puts "count2 : #{count2}"
puts "difference : #{difference}"
count1 : 1336406
count2 : 1336406
difference : 0
死锁
两个以上的运算单元，双方都在等待对方停止运行，以获取系统资源，但是没有一方提前退出时，这种状况，就称为死锁。
例如，一个进程 p1占用了显示器，同时又必须使用打印机，而打印机被进程p2占用，p2又必须使用显示器，这样就形成了死锁。
当我们在使用 Mutex 对象时需要注意线程死锁。
#!/usr/bin/ruby
require 'thread'
mutex = Mutex.new
cv = ConditionVariable.new
a = Thread.new {
mutex.synchronize {
puts "A: I have critical section, but will wait for cv"
cv.wait(mutex)
puts "A: I have critical section again! I rule!"
}
}
puts "(Later, back at the ranch...)"
b = Thread.new {
mutex.synchronize {
puts "B: Now I am critical, but am done with cv"
cv.signal
puts "B: I am still critical, finishing up"
}
}
a.join
b.join