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All fields Software Mathematics Physics Chemistry Biology Engineering Astronomy Environmental Other Software Software groups

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Search the community's STEM library — free to study, yours to make your own.

Software

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Software: explore STEM content (page 19 of 25) · openstem

Flashcards10 cards

What is the MongoDB aggregation pipeline?1 / 10

A sequence of stages that transform documents, where each stage's output feeds the next. Common stages include `$match`, `$group`, `$project`, and `$sort`.

Software

Aggregation Framework

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Aggregation Framework

Collection2 items

01Unsafe, FFI & Raw Pointers

02Async Internals, Pin & Variance

Software

Software · L4 · Rust

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Software · L4 · Rust

Collection2 items

01Rebase & Rewriting History

02Internals & Recovery

Software

Software · L3 · Git & Dev Workflow

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Software · L3 · Git & Dev Workflow

Note~94 words · 1 min

One Loop, Five Phases Node's event loop cycles through a fixed sequence of phases every tick. Libuv drives this loop, dispatching queued callbacks in each phase before moving to the next. `process.nextTick()` callbacks and resolved Promise

Software

Software · L1 · Node.js: Event Loop Walkthrough

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Software · L1 · Node.js: Event Loop Walkthrough

Collection2 items

01Kernel Internals

02Advanced OS Concepts

Software

Software · L4 · Operating Systems

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Software · L4 · Operating Systems

Note~138 words · 1 min

Why Two Concurrent Applies Are Dangerous State is Terraform's single source of truth for what it manages. If two applies write to it at once, the file can end up corrupted or missing resources — a remote backend with locking exists specific

Software

Software · L2 · Terraform: Safe Applies with Remote State & Locking

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Software · L2 · Terraform: Safe Applies with Remote State & Locking

Collection4 items

01Regular Expressions & Text Parsing

02Software · L3 · Regular Expressions & Text Parsing

03Software · L3 · Regex or Real Parser?

+1 more

Software

Software · L3 · Regex & Text Parsing

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Software · L3 · Regex & Text Parsing

Flashcards9 cards

When should you use threading vs multiprocessing vs asyncio in Python?1 / 9

Threading: I/O-bound concurrent tasks (GIL released on I/O). Multiprocessing: CPU-bound tasks (each process has its own GIL and memory). asyncio: high-concurrency I/O with a single thread via cooperative coroutines — best for network servers handling thousands of connections.

Software

Concurrency

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Concurrency

Flowchart13 objects

Software

Software · L2 · Git & Dev Workflow: Resolving a Merge Conflict · flowchart

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Software · L2 · Git & Dev Workflow: Resolving a Merge Conflict · flowchart

Note~125 words · 1 min

When Something Goes Wrong Prevention fails sometimes, no matter how strong your defenses. Incident response is the practiced sequence a team follows once an attack or breach is confirmed, so the reaction is fast and consistent rather than i

Software

Software · L2 · Security & Auth: Incident Response Basics

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Software · L2 · Security & Auth: Incident Response Basics

Collection2 items

01Async & Networking

02Rendering Pipeline

Software

Software · L3 · Flutter

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Software · L3 · Flutter

Flashcards8 cards

What is the essential difference between LL(1) and LR(1) parsing?1 / 8

LL(1) builds a parse tree top-down, predicting which production to expand next using one lookahead token — it requires a grammar with no left recursion and disjoint FIRST sets per alternative. LR(1) builds the tree bottom-up, shifting tokens onto a stack and reducing by a production once a right-hand side is fully recognized on top of it; LR(1) accepts a strictly larger class of grammars, including left-recursive ones, at the cost of a more complex, table-driven parser generator.

Software

Software · L5 · Compiler Construction Theory

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Software · L5 · Compiler Construction Theory

Quiz3 questions

Which of the following correctly characterises the class NP?

AProblems solvable in non-deterministic polynomial time, equivalently with polynomial-time verifiable certificatesBProblems solvable in polynomial time by a deterministic Turing machineCProblems whose complements are in PDProblems requiring exponential time in the worst case

Software

Software · L5 · Complexity Theory

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Software · L5 · Complexity Theory

Flashcards7 cards

Define a one-way function (OWF), and explain its role in modern cryptography.1 / 7

A function f: {0,1}* → {0,1}* is one-way if it is efficiently computable (in polynomial time) but hard to invert: for every probabilistic polynomial-time (PPT) adversary A, the probability that A(f(x)) outputs some x′ with f(x′) = f(x), over a uniformly random x, is negligible. OWFs are the minimal cryptographic primitive — Impagliazzo and Luby (1989) showed that essentially all of private-key cryptography (pseudorandom generators, pseudorandom functions, digital signatures, commitment schemes) can be built from OWFs, and conversely most of these primitives imply the existence of an OWF, making OWF existence the foundational assumption of the field.

Software

Software · L5 · Cryptographic Foundations

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Software · L5 · Cryptographic Foundations

Quiz5 questions

Which annotation maps 'many orders belong to one customer'?

A@ManyToOne on the Order entity's customer fieldB@OneToMany on the Order entityC@ManyToMany on both entitiesD@Entity on the Customer only

Software

Software · L2 · Spring Boot: Data Access & Transactions

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Software · L2 · Spring Boot: Data Access & Transactions

Flashcards9 cards

Which files does Spring Boot read external configuration from by default?1 / 9

application.properties or application.yml on the classpath (and config locations). Spring Boot binds these values into beans and supports profile-specific variants like application-dev.yml.

Software

Configuration & Properties

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Configuration & Properties

Collection2 items

01K8s Scheduling, Operators & CRDs

02Service Mesh & GitOps

Software

Software · L4 · Docker & Kubernetes

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Software · L4 · Docker & Kubernetes

Flashcards10 cards

What is the difference between a taint (on a node) and a toleration (on a Pod)?1 / 10

A taint repels Pods from a node unless the Pod has a matching toleration. Taints/tolerations work together to keep Pods OFF nodes (e.g. dedicated GPU nodes); they do not, by themselves, attract Pods — that's node affinity's job.

Software

K8s Scheduling, Operators & CRDs

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K8s Scheduling, Operators & CRDs

Note~186 words · 1 min

One Thread, Two Queues JavaScript runs on a single thread: only one piece of code executes at a time, tracked on the call stack. Asynchronous work — timers, promises, I/O — doesn't run inline; it gets scheduled onto one of two queues that t

Software

Software · L2 · JavaScript: The Event Loop

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Software · L2 · JavaScript: The Event Loop

Flashcards10 cards

What is the difference between `rem` and `em` units?1 / 10

`em` is relative to the font-size of the current element (compounds with nesting). `rem` is relative to the root (<html>) font-size — predictable and not affected by parent sizes. Prefer `rem` for consistent, scalable typography and spacing.

Software

Responsive & Modern CSS

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Responsive & Modern CSS

Flashcards10 cards

What language do you write Terraform configuration in?1 / 10

HCL (HashiCorp Configuration Language), a declarative language for describing infrastructure in .tf files. Terraform can also accept equivalent JSON.

Software

Terraform Fundamentals

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Terraform Fundamentals

Flashcards10 cards

Recite the exact order of the request pipeline, including where exception filters sit.1 / 10

Middleware → guards → interceptors (before `next.handle()`) → pipes → route handler → interceptors (after, operating on the returned stream) → response. Exception filters wrap the whole flow: any error thrown in a guard, pipe, handler, or interceptor is routed to the matching filter. Pipes run after guards because authorization should fail fast, before spending work parsing/validating input.

Software

Interceptors, Guards, Pipes & Microservices

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Interceptors, Guards, Pipes & Microservices

Flashcards11 cards

How does a replica set election decide which member becomes primary?1 / 11

Members run a Raft-like protocol: a candidate requests votes and needs a strict majority of voting members to win. Only members whose oplog is current enough are eligible, and `priority`/`votes` settings influence eligibility — so a member with stale data cannot be elected.

Software

Replication, Sharding & Consistency

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Replication, Sharding & Consistency

Flashcards10 cards

What is the difference between `&&` and `&` for booleans?1 / 10

`&&` is short-circuiting: it stops evaluating once the result is known (right side skipped if left is false). `&` always evaluates both operands. Use `&&` to guard against side effects like null checks.

Software

Syntax & Control Flow

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Syntax & Control Flow

Collection4 items

01Message Queues & Event-Driven Communication

02Software · L3 · Message Queues & Event-Driven Communication

03Software · L3 · Message Delivery and Failure Handling

+1 more

Software

Software · L3 · Message Queues & Event-Driven Communication

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Software · L3 · Message Queues & Event-Driven Communication

Quiz5 questions

Which isolation level prevents dirty, non-repeatable, and phantom reads?

ARead UncommittedBRead CommittedCRepeatable ReadDSerializable

Software

Software · L2 · SQL: Isolation Levels & Locking

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Software · L2 · SQL: Isolation Levels & Locking

Flashcards10 cards

Which S3 storage class is cheapest for rarely accessed archival data with retrieval delays acceptable?1 / 10

S3 Glacier Deep Archive offers the lowest storage cost for long-term archives where retrieval times of hours are acceptable.

Software

Storage & Content Delivery

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Storage & Content Delivery

Flashcards10 cards

What problem does the Observer pattern solve?1 / 10

It establishes a one-to-many dependency so that when a subject changes state, all registered observers are notified automatically.

Software

Behavioral Patterns

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Behavioral Patterns

Quiz5 questions

Multiple goroutines need exclusive access to a shared in-memory counter. What's the simplest fit?

AAn unbuffered channelBsync.MutexCsync.WaitGroupDselect

Software

Software · L2 · Go: Concurrency Primitives

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Software · L2 · Go: Concurrency Primitives

Flashcards10 cards

What transport-layer problem does HTTP/3 solve that HTTP/2 still has?1 / 10

HTTP/2 multiplexes streams over one TCP connection, so a single lost packet stalls ALL streams (TCP head-of-line blocking). HTTP/3 runs over QUIC (on UDP), where streams are independent, so loss on one stream doesn't block the others.

Software

HTTP/2, HTTP/3 & QUIC

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HTTP/2, HTTP/3 & QUIC

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