Concurrency Issues

When working with concurrent programs, there are several common issues that can arise. Two of the most prevalent issues are race conditions and deadlocks.

Race Conditions

A race condition occurs when the outcome of a program depends on the relative timing of events, which can lead to unpredictable and incorrect results. Race conditions typically occur when multiple threads access and modify shared resources concurrently.

Let's consider an example of a bank account balance where multiple threads can withdraw money simultaneously:

1const accountBalance = 1000;
2
3function withdraw(amount) {
4  if (amount <= accountBalance) {
5    // Simulate some processing time
6    setTimeout(() => {
7      accountBalance -= amount;
8      console.log('Withdraw successful. Remaining balance:', accountBalance);
9    }, 1000);
10  } else {
11    console.log('Insufficient funds.');
12  }
13}
14
15withdraw(500);
16withdraw(700);

xxxxxxxxxx

const accountBalance = 1000;

​

function withdraw(amount) {

  if (amount <= accountBalance) {

    // Simulate some processing time

    setTimeout(() => {

      accountBalance -= amount;

      console.log('Withdraw successful. Remaining balance:', accountBalance);

    }, 1000);

  } else {

    console.log('Insufficient funds.');

  }

}

​

withdraw(500);

withdraw(700);