Practical QA course

Performance Engineering: JMeter, k6 and System Diagnosis

From measurement fundamentals to an independent performance investigation: JMeter and k6, JVM and garbage collection, CPU, databases, pools and queues, Prometheus, Grafana, logs, tracing and profiling. Beginner explanations, diagrams, local laboratories, quizzes and an evidence-based capstone.

20 learning sessionsFull course · free

Course overview

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Course curriculum

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Lesson 1What Performance Testing measures

Theory and practice

ArticleWhat Performance Testing measures

Lesson 2Workload models

Theory and practice

ArticleWorkload models

Lesson 3Your first k6 test

Theory and practice

ArticleYour first k6 test
Knowledge checkCheck your understanding

Lesson 4Experiment types and recovery

Theory and practice

ArticleExperiment types and recovery

Lesson 5Diagnosis and hypothesis testing

Theory and practice

ArticleDiagnosis and hypothesis testing

Lesson 6Comparison and the capstone

Theory and practice

ArticleComparison and the capstone
Knowledge checkCheck your understanding

Lesson 7JMeter: from the first launch to a correct journey

Theory and practice

ArticleJMeter without mystery: installation and test anatomy
ArticleHTTP in JMeter: address, body, headers and timing
ArticleThreads, ramp-up and loops: what work are we scheduling?
ArticleDebugging a business journey: login to an order retry
Knowledge checkApplied checkpoint: test your conclusions

Lesson 8JMeter: data, correlation, assertions and user pacing

Theory and practice

ArticleCSV and data ownership: independent users
ArticleCorrelation: tokens, cookies and dependent requests
ArticleAssertions and Groovy: verify meaning without unnecessary cost
ArticleThink time, pacing and timers: defining behavior
Knowledge checkApplied checkpoint: test your conclusions

Lesson 9JMeter: CLI, results and generator reliability

Theory and practice

ArticleFrom GUI to CLI: reproducible runs and JTL
ArticleReading a JMeter report: from tables to a defensible conclusion
ArticleWhen the load generator is the bottleneck
ArticleDistributed JMeter: what multiplies and what must be partitioned
Knowledge checkApplied checkpoint: test your conclusions

Lesson 10k6: scenario code, lifecycle and criteria

Theory and practice

Articlek6 as a program: init, setup, VU and teardown
ArticleAn HTTP journey in k6: correlation and business validation
ArticleSharedArray, VU and iteration: who owns the data?
ArticleChecks, custom metrics and thresholds: when a test actually fails
Knowledge checkApplied checkpoint: test your conclusions

Lesson 11k6: workload models, VU capacity and the browser

Theory and practice

ArticleExecutors: choose a model for the experiment question
ArticleDropped iterations: why a fast test can miss its objective
ArticleTags, groups and per-operation criteria
ArticleBrowser k6 and CI: different levels of evidence
Knowledge checkApplied checkpoint: test your conclusions

Lesson 12How the system works: requests, CPU, networking and containers

Theory and practice

ArticleThe request path and latency budget
ArticleProcesses, threads, CPU and event loops without confusion
ArticleNetworking: DNS, TCP, TLS, KeepAlive and measurement boundaries
ArticleOS and container resources: quotas, RSS, disk and queues
Knowledge checkApplied checkpoint: test your conclusions

Lesson 13JVM and garbage collection: memory, mechanisms and tradeoffs

Theory and practice

ArticleWhat is a garbage collector? Objects, references and live memory
ArticleHow GC finds and reclaims memory: generations, pauses and barriers
ArticleG1, Serial, Parallel and ZGC: choosing an experiment
ArticleTuning heap, CPU and pauses: change a cause, not a flag collection
Knowledge checkApplied checkpoint: test your conclusions

Lesson 14Memory diagnosis: GC logs, JFR, leaks and other runtimes

Theory and practice

ArticleReading GC logs and post-collection trends
Articlejcmd, JFR and thread dumps: match the tool to the question
ArticleRetention and leaks: establishing that data lives too long
ArticleGC in Node.js and Python: what transfers and what does not
Knowledge checkApplied checkpoint: test your conclusions

Lesson 15Prometheus and Grafana: from measurement to a readable dashboard

Theory and practice

ArticleObservability architecture: metrics, logs, traces and profiles
ArticleCounters, gauges and histograms: modeling a metric correctly
ArticlePromQL: rates, aggregation, p95 and the correct denominator
ArticleGrafana: a dashboard that supports investigation
Knowledge checkApplied checkpoint: test your conclusions

Lesson 16Logs, traces, profiles and telemetry reliability

Theory and practice

ArticleStructured logs, Loki and LogQL
ArticleOpenTelemetry and Tempo: reading a trace beyond a long bar
ArticleProfiles and cross-signal analysis: testing an explanation
ArticleTelemetry gaps, alerts and observability cost
Knowledge checkApplied checkpoint: test your conclusions

Lesson 17Bottleneck diagnosis: from symptoms to mechanism

Theory and practice

ArticleCPU and locks: why threads stop making progress
ArticleSQL: plans, indexes, statistics and locks
ArticleConnection pools, queues and backpressure
ArticleCaches, I/O and dependencies: bottlenecks beyond CPU
Knowledge checkApplied checkpoint: test your conclusions

Lesson 18Overload, capacity and recovery

Theory and practice

ArticleLoad, stress, spike, endurance and data volume
ArticleTimeouts, deadlines, retries and idempotency
ArticleCapacity, scaling and resource headroom
ArticleRecovery, degradation and experiment boundaries
Knowledge checkApplied checkpoint: test your conclusions

Lesson 19Statistics, SLOs and evidence-based decisions

Theory and practice

ArticlePercentiles, histograms and sample adequacy
ArticleWarm-up, repeatability and fair A–B comparison
ArticleSLIs, SLOs, error budgets and release criteria
ArticleExperiment reports and CI checks
Knowledge checkApplied checkpoint: test your conclusions

Lesson 20Capstone: an independent performance investigation

Theory and practice

ArticleDesigning the capstone investigation
ArticleInvestigating an initially unknown slowdown
ArticleA change, repeated comparison and recovery verification
ArticleTechnical defense, portfolio and competence criteria
Knowledge checkApplied checkpoint: test your conclusions