Race conditions

Race conditions occur when a program depends on the timing of other concurrent events such that an unexpected code path finishes before a expected code path expected to finish earlier.

Bank account example

You can consider a bank account (with $0 balance) as an example and you wanted to:

• A friend adds $10 to the account
• You make a payment of $5 to a merchant

Assuming these operations occur simultaneously, there are two code paths here.

Code Path A

1. The incoming funds is transferred from your friend
2. The payment to the merchant is successful

Code Path B

1. The payment to the merchant gets rejected
2. The incoming funds is transferred from your friend

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For more information, see the following reference note on Race Conditions.