Build fluency in the vocabulary of preventing many concurrent requests from overwhelming an origin at once.
0 / 5 completed
1 / 5
At standup, a dev mentions a popular cache entry expiring and dozens of concurrent requests all missing the cache at once, each one hitting the slow origin database simultaneously to regenerate the exact same value. What is this problem called?
A cache stampede, or dogpile effect, happens when a popular cache entry expires and dozens of concurrent requests all miss the cache at once, each hitting the slow origin database simultaneously to regenerate the exact same value. Every request finding a valid cached value describes the opposite, normal case with no stampede at all. This simultaneous regeneration is what can suddenly overwhelm an origin database the moment a heavily requested cache entry expires.
2 / 5
During a design review, the team wants only the first request that misses the cache to actually regenerate the value, while every other concurrent request waits for that result instead of independently hitting the origin. Which capability supports this?
Request coalescing, sometimes called single-flight locking, lets only the first request that misses the cache actually regenerate the value, while every other concurrent request waits for that same result instead of independently querying the origin. Letting every concurrent request hit the origin independently multiplies the load on it by however many requests happened to arrive during that same cache-miss window. This coalescing is what keeps a cache miss from turning into a multiplied hit on the origin.
3 / 5
In a code review, a dev notices a cache entry is refreshed slightly before its expiration by a background process, so a request never actually experiences the moment the entry is fully expired and missing. What does this represent?
Early or background refresh updates a cache entry slightly before its expiration through a background process, so a request never actually experiences the moment the entry is fully expired and missing. Letting an entry sit expired until the next request arrives to regenerate it reintroduces exactly the window where a stampede of concurrent requests can pile onto the origin simultaneously. This proactive refresh is another common defense against a stampede, complementary to request coalescing.
4 / 5
An incident report shows the origin database was overwhelmed for several minutes right after a heavily requested cache entry expired, because every one of dozens of concurrent requests independently queried the database to regenerate the exact same value. What practice would prevent this?
Coalescing concurrent requests so only the first one regenerates the value, or refreshing the entry proactively before it expires, prevents exactly the kind of overwhelming, simultaneous origin load this incident describes. Letting every concurrent request independently query the origin multiplies that load by however many requests happen to arrive during the cache-miss window. This coalescing or proactive-refresh approach is a standard defense for any cache entry that's popular enough for its expiration to matter.
5 / 5
During a PR review, a teammate asks why the team adds request coalescing on top of caching instead of just trusting that a cache miss is rare enough not to need any special handling. What is the reasoning?
A popular cache entry's expiration can cause many concurrent requests to miss at exactly the same moment, especially for a heavily requested value, and without coalescing, each one independently overwhelms the origin regenerating the same result. Trusting that a miss is rare enough to ignore misses exactly this predictable failure mode for a popular entry. The tradeoff is the added implementation complexity of coordinating concurrent requests around a single in-flight regeneration rather than letting each one proceed independently.
What does the "Cache Stampede Vocabulary" vocabulary exercise cover?
This exercise tests real IT vocabulary related to cache stampede vocabulary through 5 multiple-choice questions, each built from realistic workplace sentences rather than abstract definitions.
Is this vocabulary exercise free to use?
Yes. Every exercise on CoderSlingo, including this one, is completely free — no account, sign-up, or payment required.
How many questions does this exercise have?
This exercise has 5 questions. Each one shows a real-world sentence or scenario with multiple-choice options and an explanation once you answer.
What happens after I answer a question?
You'll see immediate feedback showing whether your answer was correct, along with a short explanation of why — then a button to move to the next question, and a full results screen at the end.
Can I retry the exercise if I get questions wrong?
Yes. Once you reach the results screen, click "Try again" to reset your answers and go through the exercise from the start as many times as you like.
Do I need to create an account to take this exercise?
No account is needed. Your answers are scored in your browser during the session — nothing is saved to a server, so you can jump straight in.
Is my progress saved if I leave the page?
No — progress within an exercise resets if you navigate away or reload. Each exercise is short enough to complete in a few minutes in one sitting.
Are these vocabulary exercises connected to other topics?
Yes — this module shares real-world context with 11 other vocabulary modules. See "Related vocabulary" below to keep building a connected skill set.
How is this different from reading a glossary or blog article?
Exercises like this one are active recall drills — you have to choose the correct term or phrasing yourself, which builds retention faster than passively reading a definition.
Where can I find more vocabulary exercises?
Browse the full Vocabulary exercises hub for hundreds of modules covering Agile, DevOps, security, databases, architecture, and more — organised by IT role and skill.