[Solved] Find the problem in this Ruby code:mutex = Mutex.new counter = 0 threads = 2.times.map do Thread.new do 3.times do mutex.lock counter += 1 end mutex.unlock end end threads.each(&:join) puts counter | Ruby

Ruby - Concurrent Programming

Find the problem in this Ruby code:

mutex = Mutex.new
counter = 0
threads = 2.times.map do
  Thread.new do
    3.times do
      mutex.lock
      counter += 1
    end
    mutex.unlock
  end
end
threads.each(&:join)
puts counter

ACounter is incremented outside the lock

BMutex is never locked

CMutex is unlocked only once after multiple locks, causing deadlock

DThreads are not joined properly

Step-by-Step Solution

Solution:

Step 1: Check lock/unlock pairing
Mutex is locked 3 times inside loop but unlocked only once after loop.
Step 2: Identify consequence
This causes deadlock because locks are not properly released.
Final Answer:
Mutex is unlocked only once after multiple locks, causing deadlock -> Option C
Quick Check:
Lock/unlock must match count [OK]

Quick Trick: Unlock Mutex as many times as you lock it [OK]

Common Mistakes:

Unlocking once after multiple locks
Assuming one unlock frees all locks
Not locking Mutex before increment

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More Ruby Quizzes

Find the problem in this Ruby code:

Step 1: Check lock/unlock pairing

Step 2: Identify consequence

Final Answer:

Quick Check:

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