Mutex Implementation

Mutex Synchronization Control
Mutex State: UNLOCKED
Step: 0
Waiting: 0
Mutex Lock
UNLOCKED
Critical Section Available
No process in critical section

Threads/Processes

T1
T2
T3
T4
Waiting Queue Count: 0
No threads waiting
operation Timeline
Mutex simulation initialized
Select a scenario and click Start to begin simulation

About Mutex

A mutex (mutual exclusion) is a synchronization primitive that ensures only one thread can access a critical section at a time.

  • Lock: Acquire exclusive access to the critical section
  • Unlock: Release the critical section for other threads
  • Blocking: Threads wait if mutex is already locked
  • Ownership: Only the thread that locked can unlock

Mutex Operations

mutex_lock(mutex m) { while (m.locked) { // Wait in queue block_thread(); } m.locked = true; m.owner = current_thread; } mutex_unlock(mutex m) { if (m.owner != current_thread) { return ERROR; } m.locked = false; m.owner = NULL; wakeup_waiting_thread(); }

Scenarios

Basic Mutex:

  • Simple critical section protection
  • One thread at a time access
  • FIFO waiting queue

Bank Account:

  • Protect account balance updates
  • Prevent race conditions in transactions
  • Ensure data consistency

Printer Queue:

  • Serialize access to shared printer
  • Prevent job interference
  • Maintain print order

File Access:

  • Coordinate file read/write operations
  • Prevent data corruption
  • Ensure atomic file operations

Key Concepts

  • Atomicity: Lock/unlock operations are indivisible
  • Ownership: Only lock owner can unlock
  • Blocking: Threads wait when mutex is locked
  • Fairness: FIFO ordering prevents starvation
  • Deadlock Prevention: Proper lock ordering

How to Use

  1. Select a scenario from the dropdown
  2. Click Start to initialize the simulation
  3. Click on threads to attempt lock/unlock operations
  4. Use Step to execute one operation at a time
  5. Try Auto Demo for continuous execution
  6. Click Reset to start over

Watch how threads compete for mutex access and observe synchronization patterns!