# Error Handling / Resilience > Every principle in this category is listed as a record. Page: Ontology ยท Principles Canonical: https://banes-lab.com/ontology#arch-category-error-handling-resilience Every principle in this category is listed as a record. Each record carries its kind, its severity, the scopes it applies at and the layer it lives in, then the edge relations that join it to other records, the records that point back at it, the contracts that answer to it and the tensions it takes part in. The descriptors say how it is violated, detected, measured, repaired and enforced. Where the record carries one, an exemplar shows the shape before and after the principle is applied. Relations diagram The relations inside this category. ```mermaid flowchart LR n_defensive_programming["Defensive Programming"] n_fail_fast["Fail Fast"] n_fail_safe["Fail Safe"] n_fail_secure["Fail Secure"] n_graceful_degradation["Graceful Degradation"] n_fault_tolerance["Fault Tolerance"] n_resilience["Resilience"] n_robustness_principle["Robustness Principle"] n_error_handling["Error Handling"] n_error_boundaries["Error Boundaries"] n_fallback_pattern["Fallback Pattern"] n_retry_pattern["Retry Pattern"] n_timeout_pattern["Timeout Pattern"] n_circuit_breaker_pattern["Circuit Breaker Pattern"] n_bulkhead_pattern["Bulkhead Pattern"] n_backpressure["Backpressure"] n_defensive_programming --> n_error_handling n_defensive_programming --> n_fail_fast n_fail_fast -.-> n_graceful_degradation n_fail_safe --> n_resilience n_graceful_degradation --> n_fault_tolerance n_fault_tolerance --> n_error_handling n_fault_tolerance --> n_resilience n_resilience --> n_fault_tolerance n_error_handling --> n_resilience n_error_boundaries --> n_resilience n_fallback_pattern --> n_graceful_degradation n_retry_pattern --> n_fault_tolerance n_circuit_breaker_pattern --> n_fault_tolerance n_circuit_breaker_pattern --> n_backpressure n_backpressure --> n_resilience ``` ### Defensive Programming - Kind: [principle](https://banes-lab.com/records/kind/principle.md) - Severity: mandatory - Scope: function, module, boundary - Layer: [Correctness Core](https://banes-lab.com/records/layer/correctness-core.md) Details Requires [Input Validation](https://banes-lab.com/records/arch/input-validation.md), [Error Handling](https://banes-lab.com/records/arch/error-handling.md) Reinforces [Robustness](https://banes-lab.com/records/lex/robustness.md), [Fail Fast](https://banes-lab.com/records/arch/fail-fast.md) Enables [Safe Failure](https://banes-lab.com/records/lex/safe-failure.md) In tension with [Verbosity](https://banes-lab.com/records/lex/verbosity.md) Conflicts with [Trusting Invalid Inputs](https://banes-lab.com/records/lex/trusting-invalid-inputs.md) Tensions [Defensive Programming Verbosity](https://banes-lab.com/records/tension/defensive-programming-verbosity.md) Violated by unchecked assumptions Detected by null/empty/range unsafe access Measured by guard coverage, runtime exception rate Refactored by Add Guards, Validate Inputs Enforced by linting, [tests](https://banes-lab.com/records/lex/tests.md) Before ```typescript function renameFoo(foo: Foo, name: string) { foo.name = name.trim(); } ``` After ```typescript function renameFoo(foo: Foo | undefined, name: unknown) { if (!foo) throw new Error("Foo required"); if (typeof name !== "string" || name.trim().length === 0) throw new Error("valid name required"); return { ...foo, name: name.trim() }; } ``` ### Fail Fast - Kind: [principle](https://banes-lab.com/records/kind/principle.md) - Severity: recommended - Scope: input, startup, invariant boundary - Layer: [Correctness Core](https://banes-lab.com/records/layer/correctness-core.md) Details Requires [Preconditions](https://banes-lab.com/records/arch/preconditions.md), [Validation](https://banes-lab.com/records/arch/validation.md) Reinforces [Correctness](https://banes-lab.com/records/arch/correctness.md), [Observability](https://banes-lab.com/records/arch/observability.md) Enables [Early Defect Detection](https://banes-lab.com/records/lex/early-defect-detection.md) In tension with [Graceful Degradation](https://banes-lab.com/records/arch/graceful-degradation.md) Conflicts with [Silent Failure](https://banes-lab.com/records/lex/silent-failure.md), [Silent Data Corruption](https://banes-lab.com/records/arch/silent-data-corruption.md) Referenced by [Preconditions](https://banes-lab.com/records/arch/preconditions.md), [Defensive Programming](https://banes-lab.com/records/arch/defensive-programming.md), [Schema Validation](https://banes-lab.com/records/arch/schema-validation.md), [Input Validation](https://banes-lab.com/records/arch/input-validation.md) Tensions [Fail Fast Graceful Degradation](https://banes-lab.com/records/tension/fail-fast-graceful-degradation.md) Violated by swallowing invalid state Detected by ignored exceptions, default fallbacks masking errors Measured by late failure rate Refactored by Add Guard Clause, Throw Explicit Error Enforced by validation tests Before ```typescript const fooUrl = process.env.FOO_URL ?? "http://localhost:3000"; startFooApp(fooUrl); ``` After ```typescript const fooUrl = process.env.FOO_URL; if (!fooUrl) throw new Error("FOO_URL is required"); startFooApp(new URL(fooUrl)); ``` ### Fail Safe - Kind: [principle](https://banes-lab.com/records/kind/principle.md) - Severity: mandatory - Scope: runtime, operation, security - Layer: [Correctness Core](https://banes-lab.com/records/layer/correctness-core.md) Details Requires [Safe Defaults](https://banes-lab.com/records/lex/safe-defaults.md) Reinforces [Resilience](https://banes-lab.com/records/arch/resilience.md) Enables [Damage Limitation](https://banes-lab.com/records/lex/damage-limitation.md) In tension with [Availability](https://banes-lab.com/records/lex/availability.md) Conflicts with [Unsafe Default Continuation](https://banes-lab.com/records/lex/unsafe-default-continuation.md) Tensions [Fail Safe Availability](https://banes-lab.com/records/tension/availability-fail-safe.md) Violated by continuing in unsafe state Detected by fallback to unsafe behavior Measured by unsafe failure modes Refactored by Add Safe Fallback, Stop Unsafe Operation Enforced by failure-mode tests Before ```typescript try { await openFooGate(); } catch { fooGate.unlock(); } ``` After ```typescript try { await openFooGate(); } catch { fooGate.lock(); throw new Error("Foo gate remains locked"); } ``` ### Fail Secure - Kind: [principle](https://banes-lab.com/records/kind/principle.md) - Severity: mandatory - Scope: auth, access, infrastructure - Layer: [Correctness Core](https://banes-lab.com/records/layer/correctness-core.md) Details Requires [Secure Defaults](https://banes-lab.com/records/lex/secure-defaults.md) Reinforces [Security by Design](https://banes-lab.com/records/arch/security-by-design.md) Enables [Deny-by-Default Behavior](https://banes-lab.com/records/lex/deny-by-default-behavior.md) In tension with [Availability](https://banes-lab.com/records/lex/availability.md) Conflicts with [Fail Open](https://banes-lab.com/records/lex/fail-open.md) Referenced by [Secure by Default](https://banes-lab.com/records/arch/secure-by-default.md) Tensions [Fail Secure Availability](https://banes-lab.com/records/tension/availability-fail-secure.md) Violated by allowing access after auth/policy failure Detected by fail-open branches Measured by fail-open count Refactored by Default Deny, Add Explicit Allow Enforced by security tests, policy checks Before ```typescript function authorizeFoo(token?: string) { if (!token) return { role: "admin" }; return decodeToken(token); } ``` After ```typescript function authorizeFoo(token?: string): FooIdentity { if (!token) throw new UnauthorizedError(); const identity = verifyToken(token); if (!identity) throw new UnauthorizedError(); return identity; } ``` ### Graceful Degradation - Kind: [principle](https://banes-lab.com/records/kind/principle.md) - Severity: recommended - Scope: service, UX, system - Layer: [Correctness Core](https://banes-lab.com/records/layer/correctness-core.md) Details Requires [Fallback](https://banes-lab.com/records/lex/fallback.md), [Feature Isolation](https://banes-lab.com/records/lex/feature-isolation.md) Reinforces [Fault Tolerance](https://banes-lab.com/records/arch/fault-tolerance.md) Enables [Partial Availability](https://banes-lab.com/records/lex/partial-availability.md) In tension with [Consistency / Feature Completeness](https://banes-lab.com/records/lex/consistency-feature-completeness.md) Conflicts with [All-Or-Nothing Failure](https://banes-lab.com/records/lex/all-or-nothing-failure.md) Referenced by [Fail Fast](https://banes-lab.com/records/arch/fail-fast.md), [Fallback Pattern](https://banes-lab.com/records/arch/fallback-pattern.md) Tensions [Graceful Degradation Consistency / Feature Completeness](https://banes-lab.com/records/tension/consistency-feature-completeness-graceful-degradation.md) Violated by total outage from noncritical dependency failure Detected by critical path dependency on optional service Measured by partial availability under failure Refactored by Add Fallback, Isolate Optional Dependency Enforced by chaos tests Before ```typescript async function renderFooPage() { const foo = await fooService.get(); const bar = await barRecommendations.get(); return render(foo, bar); } ``` After ```typescript async function renderFooPage() { const foo = await fooService.get(); const bar = await barRecommendations.get().catch(() => [] as Bar[]); return render(foo, bar); } ``` ### Fault Tolerance - Kind: [quality-attribute](https://banes-lab.com/records/kind/quality-attribute.md) - Severity: contextual - Scope: service, system, infrastructure - Layer: [Correctness Core](https://banes-lab.com/records/layer/correctness-core.md) Details Requires [Redundancy](https://banes-lab.com/records/arch/redundancy.md), [Error Handling](https://banes-lab.com/records/arch/error-handling.md) Reinforces [Resilience](https://banes-lab.com/records/arch/resilience.md) Enables [Continued Operation Under Failure](https://banes-lab.com/records/lex/continued-operation-under-failure.md) In tension with [Cost](https://banes-lab.com/records/lex/cost.md) Conflicts with [Single Point of Failure](https://banes-lab.com/records/lex/single-point-of-failure.md) Referenced by [Leader Election](https://banes-lab.com/records/arch/leader-election.md), [Consensus](https://banes-lab.com/records/arch/consensus.md), [Graceful Degradation](https://banes-lab.com/records/arch/graceful-degradation.md), [Resilience](https://banes-lab.com/records/arch/resilience.md), [Retry Pattern](https://banes-lab.com/records/arch/retry-pattern.md), [Circuit Breaker Pattern](https://banes-lab.com/records/arch/circuit-breaker-pattern.md), [Redundancy](https://banes-lab.com/records/arch/redundancy.md), [Chaos Engineering](https://banes-lab.com/records/arch/chaos-engineering.md), [RAID Redundancy](https://banes-lab.com/records/arch/raid-redundancy.md) Tensions [Fault Tolerance Cost](https://banes-lab.com/records/tension/cost-fault-tolerance.md) Violated by unrecoverable dependency failure Detected by no retry/failover/fallback for critical path Measured by failure recovery rate, [availability](https://banes-lab.com/records/lex/availability.md) Refactored by Add Retry, [Failover](https://banes-lab.com/records/arch/failover.md), [Redundancy](https://banes-lab.com/records/arch/redundancy.md) Enforced by resilience tests Before ```typescript const foo = await fooReplicaA.read(id); ``` After ```typescript const foo = await firstSuccessful([ () => fooReplicaA.read(id), () => fooReplicaB.read(id), () => fooReplicaC.read(id), ]); ``` ### Resilience - Kind: [quality-attribute](https://banes-lab.com/records/kind/quality-attribute.md) - Severity: mandatory for production systems - Scope: service, system, infrastructure - Layer: [Correctness Core](https://banes-lab.com/records/layer/correctness-core.md) Details Requires [Fault Tolerance](https://banes-lab.com/records/arch/fault-tolerance.md), [Observability](https://banes-lab.com/records/arch/observability.md) Reinforces [Self-Healing](https://banes-lab.com/records/lex/self-healing.md), [Recovery](https://banes-lab.com/records/lex/recovery.md) Enables [Stability Under Stress](https://banes-lab.com/records/lex/stability-under-stress.md) In tension with [Complexity](https://banes-lab.com/records/lex/complexity.md) Conflicts with [Brittle Architecture](https://banes-lab.com/records/lex/brittle-architecture.md) Referenced by [Decentralization](https://banes-lab.com/records/arch/decentralization.md), [Autonomy](https://banes-lab.com/records/arch/autonomy.md), [Fail Safe](https://banes-lab.com/records/arch/fail-safe.md), [Fault Tolerance](https://banes-lab.com/records/arch/fault-tolerance.md), [Error Handling](https://banes-lab.com/records/arch/error-handling.md), [Error Boundaries](https://banes-lab.com/records/arch/error-boundaries.md), [Backpressure](https://banes-lab.com/records/arch/backpressure.md), [Message Queue](https://banes-lab.com/records/arch/message-queue.md), [Asynchronous Communication](https://banes-lab.com/records/arch/asynchronous-communication.md), [Compensating Transaction](https://banes-lab.com/records/arch/compensating-transaction.md), [Observability](https://banes-lab.com/records/arch/observability.md), [Service Discovery](https://banes-lab.com/records/arch/service-discovery.md), [Statelessness](https://banes-lab.com/records/arch/statelessness.md), [Self-Healing Architecture](https://banes-lab.com/records/arch/self-healing-architecture.md), [Rollback](https://banes-lab.com/records/arch/rollback.md) Tensions [Resilience Complexity](https://banes-lab.com/records/tension/complexity-resilience.md) Violated by cascading failures Detected by [failure propagation](https://banes-lab.com/records/lex/failure-propagation.md), lack of isolation Measured by MTTR, error budget, [availability](https://banes-lab.com/records/lex/availability.md) Refactored by Add Circuit Breaker, Bulkhead, [Retry](https://banes-lab.com/records/lex/retry.md), [Timeout](https://banes-lab.com/records/lex/timeout.md) Enforced by [chaos testing](https://banes-lab.com/records/reason/technique-chaos-testing.md), SLO gates Before ```typescript async function loadFoo(id: FooId) { return remoteFoo.get(id); } ``` After ```typescript async function loadFoo(id: FooId) { return circuitBreaker.execute(() => retry.withBackoff(() => remoteFoo.get(id), { attempts: 3 })); } ``` ### Robustness Principle - Kind: [principle](https://banes-lab.com/records/kind/principle.md) - Severity: contextual - Scope: protocol, API, input processing - Layer: [Correctness Core](https://banes-lab.com/records/layer/correctness-core.md) Details Requires [Strict Output](https://banes-lab.com/records/lex/strict-output.md), [Tolerant Input](https://banes-lab.com/records/lex/tolerant-input.md) Reinforces [Compatibility](https://banes-lab.com/records/lex/compatibility.md) Enables [Interoperability](https://banes-lab.com/records/arch/interoperability.md) In tension with [Strict Validation](https://banes-lab.com/records/lex/strict-validation.md) Conflicts with [Fragile Parsing](https://banes-lab.com/records/lex/fragile-parsing.md) Tensions [Robustness Principle Strict Validation](https://banes-lab.com/records/tension/robustness-principle-strict-validation.md) Violated by rejecting harmless compatible input variations Detected by parser brittleness Measured by compatibility failure rate Refactored by Normalize Input, Validate Semantics Enforced by compatibility test suite Before ```typescript function readFoo(message: any) { return { id: message.id, name: message.name }; } function writeFoo(foo: Foo) { return { ...foo, debug: globalThis }; } ``` After ```typescript function readFoo(message: unknown) { const value = FooEnvelopeSchema.parse(message); return { id: value.id, name: value.name }; } function writeFoo(foo: Foo): FooEnvelopeV1 { return { version: 1, id: foo.id, name: foo.name }; } ``` ### Error Handling - Kind: [principle](https://banes-lab.com/records/kind/principle.md) - Severity: mandatory - Scope: function, module, service - Layer: [Correctness Core](https://banes-lab.com/records/layer/correctness-core.md) Details Requires [Error Model](https://banes-lab.com/records/lex/error-model.md), [Observability](https://banes-lab.com/records/arch/observability.md) Reinforces [Resilience](https://banes-lab.com/records/arch/resilience.md), [Correctness](https://banes-lab.com/records/arch/correctness.md) Enables [Controlled Failure](https://banes-lab.com/records/lex/controlled-failure.md) In tension with [Simplicity](https://banes-lab.com/records/lex/simplicity.md) Conflicts with [Exception Swallowing](https://banes-lab.com/records/lex/exception-swallowing.md), [Exception Control Flow](https://banes-lab.com/records/arch/exception-control-flow.md) Referenced by [Defensive Programming](https://banes-lab.com/records/arch/defensive-programming.md), [Fault Tolerance](https://banes-lab.com/records/arch/fault-tolerance.md) Tensions [Error Handling Simplicity](https://banes-lab.com/records/tension/error-handling-simplicity.md) Violated by ignored errors, generic catches, lost context Detected by empty catch blocks, unchecked result errors Measured by unhandled error count Refactored by Add Error Type, Propagate Context, Handle Explicitly Enforced by linting, [tests](https://banes-lab.com/records/lex/tests.md) Before ```typescript async function loadFoo(id: FooId) { try { return await fooStore.find(id); } catch { return null; } } ``` After ```typescript type LoadFooResult = | { ok: true; value: Foo } | { ok: false; error: "NOT_FOUND" | "STORE_UNAVAILABLE" }; async function loadFoo(id: FooId): Promise { return fooStore.findResult(id); } ``` ### Error Boundaries - Kind: [pattern](https://banes-lab.com/records/kind/pattern.md) - Severity: recommended - Scope: component, UI, service boundary - Layer: [Correctness Core](https://banes-lab.com/records/layer/correctness-core.md) Details Requires [Failure Isolation](https://banes-lab.com/records/lex/failure-isolation.md) Reinforces [Resilience](https://banes-lab.com/records/arch/resilience.md) Enables [Localized Recovery](https://banes-lab.com/records/lex/localized-recovery.md) In tension with [Hidden Errors](https://banes-lab.com/records/lex/hidden-errors.md) Conflicts with [Failure Propagation](https://banes-lab.com/records/lex/failure-propagation.md) Tensions [Error Boundaries Hidden Errors](https://banes-lab.com/records/tension/error-boundaries-hidden-errors.md) Violated by uncontained failures crashing whole system Detected by uncaught exceptions crossing boundary Measured by blast radius Refactored by Add Boundary Handler, Isolate Component Enforced by failure tests Before ```typescript function renderApp() { return renderFooPanel(loadFoo()); } ``` After ```typescript function FooBoundary({ render }: { render(): View }) { try { return render(); } catch (error) { return renderFooError(toFooError(error)); } } const app = FooBoundary({ render: () => renderFooPanel(loadFoo()) }); ``` ### Fallback Pattern - Kind: [pattern](https://banes-lab.com/records/kind/pattern.md) - Severity: contextual - Scope: service, dependency call - Layer: [Correctness Core](https://banes-lab.com/records/layer/correctness-core.md) Details Requires [Alternate Behavior](https://banes-lab.com/records/lex/alternate-behavior.md) Reinforces [Graceful Degradation](https://banes-lab.com/records/arch/graceful-degradation.md) Enables [Partial Availability](https://banes-lab.com/records/lex/partial-availability.md) In tension with [Stale/Reduced Results](https://banes-lab.com/records/lex/stale-reduced-results.md) Conflicts with [Single Behavior Path](https://banes-lab.com/records/lex/single-behavior-path.md) Tensions [Fallback Pattern Stale/Reduced Results](https://banes-lab.com/records/tension/fallback-pattern-stale-reduced-results.md) Violated by no alternate path for noncritical dependency Detected by hard dependency in optional path Measured by fallback coverage Refactored by Add Fallback Response/Provider Enforced by failure injection tests Before ```typescript const foo = await primaryFooStore.find(id); ``` After ```typescript const foo = await primaryFooStore.find(id).catch(() => replicaFooStore.find(id)); if (!foo) throw new FooUnavailableError(id); ``` ### Retry Pattern - Kind: [pattern](https://banes-lab.com/records/kind/pattern.md) - Severity: contextual - Scope: network, IO, message handling - Layer: [Correctness Core](https://banes-lab.com/records/layer/correctness-core.md) Details Requires [Idempotency](https://banes-lab.com/records/arch/idempotency.md), [Timeout](https://banes-lab.com/records/lex/timeout.md), [Backoff](https://banes-lab.com/records/lex/backoff.md) Reinforces [Fault Tolerance](https://banes-lab.com/records/arch/fault-tolerance.md) Enables [Transient Failure Recovery](https://banes-lab.com/records/lex/transient-failure-recovery.md) In tension with [Load Amplification](https://banes-lab.com/records/lex/load-amplification.md) Conflicts with [Non-Idempotent Operation](https://banes-lab.com/records/lex/non-idempotent-operation.md) Tensions [Retry Pattern Load Amplification](https://banes-lab.com/records/tension/load-amplification-retry-pattern.md) Violated by blind retry without backoff/idempotency Detected by retry loops without timeout/backoff Measured by retry success rate, retry storm rate Refactored by Add Exponential Backoff, Idempotency Key Enforced by resilience libraries, policy checks Before ```typescript await remoteFoo.save(foo); ``` After ```typescript await retry.withBackoff( () => remoteFoo.save(foo), { attempts: 3, retryIf: isTransientError, jitter: true }, ); ``` ### Timeout Pattern - Kind: [pattern](https://banes-lab.com/records/kind/pattern.md) - Severity: mandatory - Scope: network, IO, dependency call - Layer: [Correctness Core](https://banes-lab.com/records/layer/correctness-core.md) Details Requires [Time Budget](https://banes-lab.com/records/lex/time-budget.md) Reinforces [Fault Isolation](https://banes-lab.com/records/lex/fault-isolation.md) Enables [Bounded Waiting](https://banes-lab.com/records/lex/bounded-waiting.md) In tension with [Slow Operation Tolerance](https://banes-lab.com/records/lex/slow-operation-tolerance.md) Conflicts with [Infinite Wait](https://banes-lab.com/records/lex/infinite-wait.md), [Timeout Omission](https://banes-lab.com/records/arch/timeout-omission.md) Tensions [Timeout Pattern Slow Operation Tolerance](https://banes-lab.com/records/tension/slow-operation-tolerance-timeout-pattern.md) Violated by external calls without timeout Detected by missing timeout config Measured by timeout coverage, latency tail Refactored by Add Timeout, Propagate Deadline Enforced by lint/config checks Before ```typescript const foo = await remoteFoo.find(id); ``` After ```typescript const foo = await withTimeout(remoteFoo.find(id), 500, () => new FooTimeoutError(id)); ``` ### Circuit Breaker Pattern - Kind: [pattern](https://banes-lab.com/records/kind/pattern.md) - Severity: contextual - Scope: dependency call, service - Layer: [Correctness Core](https://banes-lab.com/records/layer/correctness-core.md) Details Requires [Failure Threshold](https://banes-lab.com/records/lex/failure-threshold.md), [Fallback](https://banes-lab.com/records/lex/fallback.md) Reinforces [Fault Tolerance](https://banes-lab.com/records/arch/fault-tolerance.md), [Backpressure](https://banes-lab.com/records/arch/backpressure.md) Enables [Cascading Failure Prevention](https://banes-lab.com/records/lex/cascading-failure-prevention.md) In tension with [Availability of Degraded Dependency](https://banes-lab.com/records/lex/availability-of-degraded-dependency.md) Conflicts with [Unbounded Retry](https://banes-lab.com/records/lex/unbounded-retry.md), [Retry Storm](https://banes-lab.com/records/arch/retry-storm.md) Tensions [Circuit Breaker Pattern Availability of Degraded Dependency](https://banes-lab.com/records/tension/availability-of-degraded-dependency-circuit-breaker-pattern.md) Violated by continuing calls to failing dependency Detected by high failure dependency calls without breaker Measured by breaker trip rate, downstream error rate Refactored by Add Circuit Breaker Enforced by [resilience policy](https://banes-lab.com/records/algo/resilience-policy.md) Before ```typescript async function loadFoo(id: FooId) { return remoteFoo.find(id); } ``` After ```typescript const fooBreaker = new CircuitBreaker({ failureThreshold: 5, resetAfterMs: 30_000 }); async function loadFoo(id: FooId) { return fooBreaker.execute(() => remoteFoo.find(id)); } ``` ### Bulkhead Pattern - Kind: [pattern](https://banes-lab.com/records/kind/pattern.md) - Severity: contextual - Scope: resource pool, service, runtime - Layer: [Correctness Core](https://banes-lab.com/records/layer/correctness-core.md) Details Requires [Resource Isolation](https://banes-lab.com/records/lex/resource-isolation.md) Reinforces [Fault Isolation](https://banes-lab.com/records/lex/fault-isolation.md) Enables [Blast-Radius Reduction](https://banes-lab.com/records/lex/blast-radius-reduction.md) In tension with [Resource Utilization](https://banes-lab.com/records/arch/resource-utilization.md) Conflicts with [Shared Resource Pool](https://banes-lab.com/records/lex/shared-resource-pool.md) Tensions [Bulkhead Pattern Resource Utilization](https://banes-lab.com/records/tension/bulkhead-pattern-resource-utilization.md) Violated by one dependency consuming all threads/connections Detected by shared pools across critical/noncritical workloads Measured by resource saturation isolation Refactored by Split Resource Pools, Add Isolation Enforced by resource policy Before ```typescript const pool = new WorkerPool(100); pool.submit(fooTask); pool.submit(barTask); ``` After ```typescript const fooPool = new WorkerPool(20); const barPool = new WorkerPool(20); fooPool.submit(fooTask); barPool.submit(barTask); ``` ### Backpressure - Kind: [mechanism](https://banes-lab.com/records/kind/mechanism.md) - Severity: mandatory for high-load systems - Scope: stream, queue, service - Layer: [Correctness Core](https://banes-lab.com/records/layer/correctness-core.md) Details Requires [Capacity Signaling](https://banes-lab.com/records/lex/capacity-signaling.md) Reinforces [Resilience](https://banes-lab.com/records/arch/resilience.md), [Stability](https://banes-lab.com/records/lex/stability.md) Enables [Overload Protection](https://banes-lab.com/records/lex/overload-protection.md) In tension with [Throughput](https://banes-lab.com/records/arch/throughput.md) Conflicts with [Unbounded Ingestion](https://banes-lab.com/records/lex/unbounded-ingestion.md), [Missing Backpressure](https://banes-lab.com/records/arch/missing-backpressure.md) Referenced by [Circuit Breaker Pattern](https://banes-lab.com/records/arch/circuit-breaker-pattern.md), [Message Queue](https://banes-lab.com/records/arch/message-queue.md), [Rate Limiting](https://banes-lab.com/records/arch/rate-limiting.md), [Streaming Architecture](https://banes-lab.com/records/arch/streaming-architecture.md) Tensions [Backpressure Throughput](https://banes-lab.com/records/tension/backpressure-throughput.md) Violated by unbounded queues, uncontrolled producers Detected by queue growth without throttling Measured by queue depth, rejection/throttle rate Refactored by Add Rate Limit, Bounded Queue, Demand Signal Enforced by load tests, runtime policies Before ```typescript stream.on("data", foo => processFoo(foo)); ``` After ```typescript for await (const foo of stream) { await capacity.acquire(); void processFoo(foo).finally(() => capacity.release()); } ``` ## Links to - [principle](https://banes-lab.com/records/kind/principle.md) - [Correctness Core](https://banes-lab.com/records/layer/correctness-core.md) - [Input Validation](https://banes-lab.com/records/arch/input-validation.md) - [Error Handling](https://banes-lab.com/records/arch/error-handling.md) - [Robustness](https://banes-lab.com/records/lex/robustness.md) - [Fail Fast](https://banes-lab.com/records/arch/fail-fast.md) - [Safe Failure](https://banes-lab.com/records/lex/safe-failure.md) - [Verbosity](https://banes-lab.com/records/lex/verbosity.md) - [Trusting Invalid Inputs](https://banes-lab.com/records/lex/trusting-invalid-inputs.md) - [Defensive Programming / Verbosity](https://banes-lab.com/records/tension/defensive-programming-verbosity.md) - [Tests](https://banes-lab.com/records/lex/tests.md) - [Preconditions](https://banes-lab.com/records/arch/preconditions.md) - [Validation](https://banes-lab.com/records/arch/validation.md) - [Correctness](https://banes-lab.com/records/arch/correctness.md) - [Observability](https://banes-lab.com/records/arch/observability.md) - [Early Defect Detection](https://banes-lab.com/records/lex/early-defect-detection.md) - [Graceful Degradation](https://banes-lab.com/records/arch/graceful-degradation.md) - [Silent Failure](https://banes-lab.com/records/lex/silent-failure.md) - [Silent Data Corruption](https://banes-lab.com/records/arch/silent-data-corruption.md) - [Defensive Programming](https://banes-lab.com/records/arch/defensive-programming.md) - [Schema Validation](https://banes-lab.com/records/arch/schema-validation.md) - [Fail Fast / Graceful Degradation](https://banes-lab.com/records/tension/fail-fast-graceful-degradation.md) - [Safe Defaults](https://banes-lab.com/records/lex/safe-defaults.md) - [Resilience](https://banes-lab.com/records/arch/resilience.md) - [Damage Limitation](https://banes-lab.com/records/lex/damage-limitation.md) - [Availability](https://banes-lab.com/records/lex/availability.md) - [Unsafe Default Continuation](https://banes-lab.com/records/lex/unsafe-default-continuation.md) - [Fail Safe / Availability](https://banes-lab.com/records/tension/availability-fail-safe.md) - [Secure Defaults](https://banes-lab.com/records/lex/secure-defaults.md) - [Security by Design](https://banes-lab.com/records/arch/security-by-design.md) - [Deny-by-Default Behavior](https://banes-lab.com/records/lex/deny-by-default-behavior.md) - [Fail Open](https://banes-lab.com/records/lex/fail-open.md) - [Secure by Default](https://banes-lab.com/records/arch/secure-by-default.md) - [Fail Secure / Availability](https://banes-lab.com/records/tension/availability-fail-secure.md) - [Fallback](https://banes-lab.com/records/lex/fallback.md) - [Feature Isolation](https://banes-lab.com/records/lex/feature-isolation.md) - [Fault Tolerance](https://banes-lab.com/records/arch/fault-tolerance.md) - [Partial Availability](https://banes-lab.com/records/lex/partial-availability.md) - [Consistency / Feature Completeness](https://banes-lab.com/records/lex/consistency-feature-completeness.md) - [All-Or-Nothing Failure](https://banes-lab.com/records/lex/all-or-nothing-failure.md) - [Fallback Pattern](https://banes-lab.com/records/arch/fallback-pattern.md) - [Graceful Degradation / Consistency / Feature Completeness](https://banes-lab.com/records/tension/consistency-feature-completeness-graceful-degradation.md) - [quality-attribute](https://banes-lab.com/records/kind/quality-attribute.md) - [Redundancy](https://banes-lab.com/records/arch/redundancy.md) - [Continued Operation Under Failure](https://banes-lab.com/records/lex/continued-operation-under-failure.md) - [Cost](https://banes-lab.com/records/lex/cost.md) - [Single Point of Failure](https://banes-lab.com/records/lex/single-point-of-failure.md) - [Leader Election](https://banes-lab.com/records/arch/leader-election.md) - [Consensus](https://banes-lab.com/records/arch/consensus.md) - [Retry Pattern](https://banes-lab.com/records/arch/retry-pattern.md) - [Circuit Breaker Pattern](https://banes-lab.com/records/arch/circuit-breaker-pattern.md) - [Chaos Engineering](https://banes-lab.com/records/arch/chaos-engineering.md) - [RAID Redundancy](https://banes-lab.com/records/arch/raid-redundancy.md) - [Fault Tolerance / Cost](https://banes-lab.com/records/tension/cost-fault-tolerance.md) - [Failover](https://banes-lab.com/records/arch/failover.md) - [Self-Healing](https://banes-lab.com/records/lex/self-healing.md) - [Recovery](https://banes-lab.com/records/lex/recovery.md) - [Stability Under Stress](https://banes-lab.com/records/lex/stability-under-stress.md) - [Complexity](https://banes-lab.com/records/lex/complexity.md) - [Brittle Architecture](https://banes-lab.com/records/lex/brittle-architecture.md) - [Decentralization](https://banes-lab.com/records/arch/decentralization.md) - [Autonomy](https://banes-lab.com/records/arch/autonomy.md) - [Fail Safe](https://banes-lab.com/records/arch/fail-safe.md) - [Error Boundaries](https://banes-lab.com/records/arch/error-boundaries.md) - [Backpressure](https://banes-lab.com/records/arch/backpressure.md) - [Message Queue](https://banes-lab.com/records/arch/message-queue.md) - [Asynchronous Communication](https://banes-lab.com/records/arch/asynchronous-communication.md) - [Compensating Transaction](https://banes-lab.com/records/arch/compensating-transaction.md) - [Service Discovery](https://banes-lab.com/records/arch/service-discovery.md) - [Statelessness](https://banes-lab.com/records/arch/statelessness.md) - [Self-Healing Architecture](https://banes-lab.com/records/arch/self-healing-architecture.md) - [Rollback](https://banes-lab.com/records/arch/rollback.md) - [Resilience / Complexity](https://banes-lab.com/records/tension/complexity-resilience.md) - [Failure Propagation](https://banes-lab.com/records/lex/failure-propagation.md) - [Retry](https://banes-lab.com/records/lex/retry.md) - [Timeout](https://banes-lab.com/records/lex/timeout.md) - [Chaos Testing](https://banes-lab.com/records/reason/technique-chaos-testing.md) - [Strict Output](https://banes-lab.com/records/lex/strict-output.md) - [Tolerant Input](https://banes-lab.com/records/lex/tolerant-input.md) - [Compatibility](https://banes-lab.com/records/lex/compatibility.md) - [Interoperability](https://banes-lab.com/records/arch/interoperability.md) - [Strict Validation](https://banes-lab.com/records/lex/strict-validation.md) - [Fragile Parsing](https://banes-lab.com/records/lex/fragile-parsing.md) - [Robustness Principle / Strict Validation](https://banes-lab.com/records/tension/robustness-principle-strict-validation.md) - [Error Model](https://banes-lab.com/records/lex/error-model.md) - [Controlled Failure](https://banes-lab.com/records/lex/controlled-failure.md) - [Simplicity](https://banes-lab.com/records/lex/simplicity.md) - [Exception Swallowing](https://banes-lab.com/records/lex/exception-swallowing.md) - [Exception Control Flow](https://banes-lab.com/records/arch/exception-control-flow.md) - [Error Handling / Simplicity](https://banes-lab.com/records/tension/error-handling-simplicity.md) - [pattern](https://banes-lab.com/records/kind/pattern.md) - [Failure Isolation](https://banes-lab.com/records/lex/failure-isolation.md) - [Localized Recovery](https://banes-lab.com/records/lex/localized-recovery.md) - [Hidden Errors](https://banes-lab.com/records/lex/hidden-errors.md) - [Error Boundaries / Hidden Errors](https://banes-lab.com/records/tension/error-boundaries-hidden-errors.md) - [Alternate Behavior](https://banes-lab.com/records/lex/alternate-behavior.md) - [Stale/Reduced Results](https://banes-lab.com/records/lex/stale-reduced-results.md) - [Single Behavior Path](https://banes-lab.com/records/lex/single-behavior-path.md) - [Fallback Pattern / Stale/Reduced Results](https://banes-lab.com/records/tension/fallback-pattern-stale-reduced-results.md) - [Idempotency](https://banes-lab.com/records/arch/idempotency.md) - [Backoff](https://banes-lab.com/records/lex/backoff.md) - [Transient Failure Recovery](https://banes-lab.com/records/lex/transient-failure-recovery.md) - [Load Amplification](https://banes-lab.com/records/lex/load-amplification.md) - [Non-Idempotent Operation](https://banes-lab.com/records/lex/non-idempotent-operation.md) - [Retry Pattern / Load Amplification](https://banes-lab.com/records/tension/load-amplification-retry-pattern.md) - [Time Budget](https://banes-lab.com/records/lex/time-budget.md) - [Fault Isolation](https://banes-lab.com/records/lex/fault-isolation.md) - [Bounded Waiting](https://banes-lab.com/records/lex/bounded-waiting.md) - [Slow Operation Tolerance](https://banes-lab.com/records/lex/slow-operation-tolerance.md) - [Infinite Wait](https://banes-lab.com/records/lex/infinite-wait.md) - [Timeout Omission](https://banes-lab.com/records/arch/timeout-omission.md) - [Timeout Pattern / Slow Operation Tolerance](https://banes-lab.com/records/tension/slow-operation-tolerance-timeout-pattern.md) - [Failure Threshold](https://banes-lab.com/records/lex/failure-threshold.md) - [Cascading Failure Prevention](https://banes-lab.com/records/lex/cascading-failure-prevention.md) - [Availability of Degraded Dependency](https://banes-lab.com/records/lex/availability-of-degraded-dependency.md) - [Unbounded Retry](https://banes-lab.com/records/lex/unbounded-retry.md) - [Retry Storm](https://banes-lab.com/records/arch/retry-storm.md) - [Circuit Breaker Pattern / Availability of Degraded Dependency](https://banes-lab.com/records/tension/availability-of-degraded-dependency-circuit-breaker-pattern.md) - [Resilience Policy](https://banes-lab.com/records/algo/resilience-policy.md) - [Resource Isolation](https://banes-lab.com/records/lex/resource-isolation.md) - [Blast-Radius Reduction](https://banes-lab.com/records/lex/blast-radius-reduction.md) - [Resource Utilization](https://banes-lab.com/records/arch/resource-utilization.md) - [Shared Resource Pool](https://banes-lab.com/records/lex/shared-resource-pool.md) - [Bulkhead Pattern / Resource Utilization](https://banes-lab.com/records/tension/bulkhead-pattern-resource-utilization.md) - [mechanism](https://banes-lab.com/records/kind/mechanism.md) - [Capacity Signaling](https://banes-lab.com/records/lex/capacity-signaling.md) - [Stability](https://banes-lab.com/records/lex/stability.md) - [Overload Protection](https://banes-lab.com/records/lex/overload-protection.md) - [Throughput](https://banes-lab.com/records/arch/throughput.md) - [Unbounded Ingestion](https://banes-lab.com/records/lex/unbounded-ingestion.md) - [Missing Backpressure](https://banes-lab.com/records/arch/missing-backpressure.md) - [Rate Limiting](https://banes-lab.com/records/arch/rate-limiting.md) - [Streaming Architecture](https://banes-lab.com/records/arch/streaming-architecture.md) - [Backpressure / Throughput](https://banes-lab.com/records/tension/backpressure-throughput.md) ## Linked from - [The layer topology](https://banes-lab.com/ontology/schema/the-layer-topology.md) - [The membership](https://banes-lab.com/ontology/schema/the-membership.md)