Race Condition

✅ Race Condition

when several processes need shared resource at the same time, can affect the result value
when accessed at concurrent time, data integrity ⬇️

• several process attempt shared resource
• timing, order can affect result

✅ When Race Condition occurs

1. Interrupt while kernel

• using data in kernel mode
• interrupt
• alter data
• global variable in kernel is shared resource

• prone to race condition
  

• 💊 while working in kernel mode, disable interrupt
• interrupt cannot take CPU control

2. System call

• process makes system call
• enter kernel mode

• context switching occurs
  

• Process 1 in kernel mode, modifying data
• CPU timeout

• CPU control goes over to Process 2
  

• 💊 If process is working in kernel mode, even if timeout, CPU control should not go over to next process

3. Multi Process environment, while accessing shared memory kernel data

• In multi processing environment

• two CPUs enter kernel for shared data, alter data
  

• 💊 lock data when shared data is accessed