# Threads

Agora que entendemos como funciona o forking de processos, vamos explorar as **threads**. Threads são uma forma mais leve de concorrência, permitindo que múltiplas tarefas sejam executadas dentro do mesmo processo, compartilhando o mesmo espaço de memória.

Conforme explicado no módulo de C, conseguimos criar POSIX Threads através da chamada de função `pthread_create`. Na linguagem Ruby, conseguimos manipular kernel threads [através da classe Thread.](https://ruby-doc.org/core-3.0.0/Thread.html)

<figure><img src="/files/mIbCMIxb7flXRlCbORAu" alt="" width="563"><figcaption></figcaption></figure>

```ruby
# Função que será executada pela thread
def handle
  puts "Hello from thread!"
end

# Cria uma thread
thread = Thread.new do
  handle
end

puts "Hello from main thread!"

# Aguarda a thread terminar
thread.join
```

```
Hello from main thread!
Hello from thread!
```

*Simples, não?* Podíamos também passar qualquer código Ruby pra dentro do bloco da thread, não precisa ser necessariamente um método:

```ruby
# Cria uma thread
thread = Thread.new do
  puts "Hello from thread!"
end

puts "Hello from main thread!"

# Aguarda a thread terminar
thread.join
```

## Um exemplo mais robusto

Agora vamos fazer um exemplo mais complexo com threads, assim como fizemos com forking de processos:

```ruby
def handle(thread_id)
  puts "Thread #{thread_id} is running..."
  sleep(2) # Simula uma tarefa que leva 2 segundos
  puts "Thread #{thread_id} is finished."
end

threads = []

# Criação das threads
3.times do |i|
  threads << Thread.new(i + 1) do |thread_id|
    handle(thread_id) # Passa o ID da thread como argumento
  end
end

# Aguarda todas as threads finalizarem
threads.each_with_index do |thread, i|
  thread.join
  puts "Thread #{i + 1} has been finished."
end

puts "All threads are finished."
```

```
Thread 1 is running...
Thread 2 is running...
Thread 3 is running...
Thread 1 is finished.
Thread 3 is finished.
Thread 2 is finished.
Thread 1 has been finished.
Thread 2 has been finished.
Thread 3 has been finished.
All threads are finished.
```

*Ruby dispensa comentários, não?*

***

Vamos agora ver como Ruby resolve problemas de **race condition.**


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://concorrencia101.leandronsp.com/parte-ii-concorrencia-em-diferentes-linguagens/concorrencia-em-ruby/threads.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.