Ruby - Main Thread and Sub-threads

1. Introduction

Threading in Ruby allows for the concurrent execution of tasks. While many are familiar with the creation of sub-threads, it's essential to recognize that a program also has a main thread, which is where the execution starts. In this post, we will demonstrate the main thread and how it interacts with sub-threads in Ruby.

The main thread is the initial thread of execution when a program starts. Every Ruby program has at least the main thread, and it can spawn additional sub-threads to perform tasks concurrently. These sub-threads run in parallel with the main thread and with each other, allowing for efficient multitasking.

2. Program Steps

1. Start the main program.

2. Print a message from the main thread.

3. Create and start multiple sub-threads.

4. Optionally, wait for the sub-threads to finish using the join method.

5. Print a concluding message from the main thread.

3. Code Program

# Starting the main program (main thread starts by default)
# Step 2: Print a message from the main thread
puts "Main thread starts."
# Step 3: Create and start sub-threads
sub_thread1 = Thread.new do
  3.times do |i|
    puts "Sub-thread 1 printing: #{i}"
    sleep(1)
  end
end
sub_thread2 = Thread.new do
  3.times do |i|
    puts "Sub-thread 2 printing: #{i}"
    sleep(1.5)
  end
end
# Step 4: Wait for sub-threads to finish
sub_thread1.join
sub_thread2.join
# Step 5: Print concluding message from the main thread
puts "Main thread concludes."

Output:

Main thread starts.
Sub-thread 1 printing: 0
Sub-thread 2 printing: 0
Sub-thread 1 printing: 1
Sub-thread 2 printing: 1
Sub-thread 1 printing: 2
Sub-thread 2 printing: 2
Main thread concludes.

Explanation:

1. Main thread: This is the primary thread of execution in any Ruby program. In our example, the main thread starts by default when the program runs and prints the initial and concluding messages.

2. Sub-thread: These are threads spawned from the main thread to carry out tasks concurrently. We've created two sub-threads in our example, sub_thread1 and sub_thread2.

3. Thread.new: This method creates a new thread and starts its execution. The code inside the block is what the thread will execute.

4. sleep: This method pauses the thread for a specified number of seconds. It's used here to simulate time-consuming tasks and to make the output easier to read.

5. join: This method is called on a thread object (like sub_thread1) and causes the main thread to wait for the sub-thread to finish its execution.

By understanding and properly managing the main thread and sub-threads, developers can harness the power of concurrent execution in Ruby.


Related Ruby Examples:

Ruby - Print Hello World Ruby - Get User Input Ruby - Display Current Date and Time Ruby - Print Environment Variables Ruby - Explain Variable Scopes Ruby - Calculate the Sum of Two Numbers Ruby - Find the Factorial of a Number Ruby - Check If a Number is Even or Odd Ruby - Generate a Random Number Ruby - Implement the Pythagorean Theorem Ruby - Calculate the Square Root of a Number Ruby - Check if a Number is Prime Ruby - Find the Greatest Common Divisor (GCD) Ruby - Check Leap Year Ruby - Print Power of a Number Ruby - Print Fibonacci Series Ruby - Count the Number of Digits in a Number Ruby - Unary operators Ruby - Arithmetic operators Ruby - Bitwise operators Ruby - Logical operators Ruby - Ternary operator Ruby - Assignment operators Ruby - Comparison operators Ruby - Convert a String to Uppercase and Lowercase Ruby - Reverse a String Ruby - Count Vowels in a String Ruby - Find the Length of a String Ruby - Replace Substrings Ruby - Split a String into Words Ruby - Join an Array into a String Ruby - Check if a String Starts with Another String Ruby - Check if a String is a Palindrome Ruby - Find the Length of an Array Ruby - Find the Maximum Element in an Array Ruby - Find the Minimum Element in an Array Ruby - Search for an Element in an Array Ruby - Sort an Array Ruby - Reverse an Array Ruby - Array Create, Add, and Remove Example Ruby - Merge Two Arrays Ruby - Create and Use a Hash Ruby - Find the Size of a Hash Ruby - Check if a Key Exists in a Hash Ruby - Merge Two Hashes Ruby - Iterate Over a Hash Ruby - If-Else Condition Ruby - Case Statement Ruby - While Loop Ruby - For Loop Ruby - OOPs Concepts Ruby - Define and Instantiate a Simple Class Ruby - Instance Variables Ruby - Class Methods and Variables Ruby - Inheritance Example Ruby - Polymorphism Example Ruby - Abstraction Example Ruby - Modules and Mixins Ruby - Encapsulation Example Ruby - Association Example Ruby - Composition Example Ruby - Aggregation Example Ruby - method_missing Example Ruby - define_method Example Ruby - Create Custom Exception Class Ruby - Create a New File and Write Content Ruby - Open and Read from a File Ruby - Append Data to an Existing File Ruby - Delete a File Ruby - Different File Modes Ruby - Read a File Line by Line Ruby - Create a New Directory Ruby - Rename a Directory Ruby - Delete a Directory Ruby - Check if a File Exists Ruby - Get a File Size Ruby - Check if a Path is a File or a Directory Ruby - Get File Modification Time Ruby - Count Number of Words in a File Ruby - Count Occurrences of a Specific Word in a File Ruby - Compress a File using Gzip Ruby - Extract a Gzip Compressed File Ruby - Create a Tar Archive Ruby - Handle Division by Zero Exception Ruby - Handle NoMethodError by Using begin-rescue-end Ruby - Handle Custom Exceptions using rescue Ruby - Handle Custom Exceptions using rescue Ruby - Handle Multiple Exceptions Using Multiple rescue Blocks Ruby - Print the Backtrace of an Exception Ruby - Define Global Exception Handling using at_exit

Ruby Tutorials

Ruby Hash Tutorial Ruby String Tutorial Ruby Array Tutorial Ruby - Match a Pattern in a String Ruby - map Function Example Ruby - reduce Function Example Ruby - select Function Example Ruby - Date and Time Example Ruby - Create and Execute a Basic Thread Ruby - Main Thread and Sub-threads Ruby - Pause Execution of Thread Using sleep Ruby - Terminate a Thread Using Thread.kill Ruby - Check Status of a Thread Using alive? Ruby - Thread Priority Example Ruby - Use Thread.pass for Thread Scheduling Ruby - Thread Local Variables Ruby Convert String to Hash Ruby Convert String to JSON Ruby Convert String to Integer Ruby Convert String to Array Ruby Convert String to Date Ruby Convert String to CamelCase Ruby Convert String to Boolean Ruby Convert String to Float Ruby Convert String to DateTime Ruby Convert Number to String Ruby Convert Number to Binary Ruby Convert Number to Boolean Ruby Convert List to Set Ruby Convert List to String Ruby Convert List to Hash Ruby Convert List to Map Ruby Convert Array to List Ruby Convert Array to Hash Ruby Convert Array to Hash With Index as Key Ruby Convert Array to Set Ruby Convert Array to String Comma Separated Ruby Convert Array of Strings to Integers Ruby Convert Array to JSON Ruby Convert Array of Hashes to JSON Ruby Convert Hash to JSON Ruby Convert Hash to String Ruby Convert Hash to Array Convert Hash Keys to Strings Ruby Convert Date to DateTime Ruby Convert Date to Epoch Ruby Convert Date to TimeStamp Ruby Convert Date to Milliseconds

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