30.34 Multiple Instances Without Synchronization

Multiple concurrent instances of a task run in parallel; the process continues without waiting for all instances to complete. Results are written to a shared output as each instance finishes — no synchronization barrier exists.


Motivating Scenario

An AI news monitoring system ingests 50 news sources simultaneously. At 06:00 each morning, a spawn task launches one News Monitor agent per source. Each agent fetches, summarizes, and scores articles from its assigned source. As each agent completes, its articles are appended to the shared feed immediately. The main process does not wait — it advances to the Publish Feed step right after spawning all monitors, regardless of how many have finished.

The key insight: timeliness matters more than completeness. A feed published at 06:05 with 30 sources is more valuable than one published at 06:30 with all 50. Readers who open the feed early get partial but fresh coverage. Late-completing monitors append to the live feed as they finish. No synchronization gate means no latency penalty for slow sources.

Structure

Zoom and pan enabled · Concrete example: AI news monitoring feed

Key Metrics

MetricSignal
Monitor completion rate Fraction of spawned instances that complete within the cycle window — tracks reliability across sources
Feed latency (first article) Time from spawn to first article in the shared feed — primary user-facing latency signal
Feed coverage at publish Fraction of sources represented at publication time — monitors the timeliness/completeness tradeoff
Write conflict rate Concurrent write failures per cycle — signals storage backend saturation
NodeWhat it doesWhat it receivesWhat it produces
Spawn Monitors Reads source list; fires one News Monitor instance per source via AND split. Does not wait for completions. Source list (50 URLs) 50 parallel agent activations
News Monitor Fetches source, extracts articles, scores relevance, summarizes each item. Writes directly to shared feed on completion. Single source URL + scoring criteria Scored article batch appended to shared feed
Publish Feed Publishes the current state of the shared feed to subscribers. Triggered immediately after spawn — not gated on monitor completions. Shared feed (partially populated) Published feed snapshot

When to Use

Use when
Avoid when

Value Profile

Origin of ValueWhere it appearsHow it is captured
Future Cashflow Published feed quality over time More sources processed per cycle compounds coverage. Each monitor that completes adds incremental value to the feed.
Conditional Action Each News Monitor instance Every monitor consumes compute only while running. Failed or slow instances do not block cost recovery on fast completions.
Risk Exposure Shared feed (write contention) Concurrent writes to a shared accumulator can corrupt order or deduplicate incorrectly. Append semantics with idempotent keys mitigate this.
Pattern contrast. 30.34 is the fire-and-forget variant of multiple instances. Value is extracted from each instance independently. 30.35 and 30.36 extract value only after all instances complete — appropriate when the aggregate matters, not the individual.

Dynamics and Failure Modes

Phantom completions

A monitor agent crashes silently after partial execution and writes incomplete data to the shared feed. Because there is no sync gate, the incomplete entry is published. Fix: require each monitor to write a completion marker before its results are accepted by the feed. Entries without a marker are excluded from publication.

Write storm on spawn

All 50 monitors complete within the same 100ms window and simultaneously attempt to write to the shared feed. Depending on the storage backend, this produces lock contention or write failures. Fix: use an append-only log with keyed writes, or route results through a lightweight queue that serializes feed writes.

Downstream consumers see inconsistent state

The Publish Feed step snapshots the feed immediately after spawn, when zero monitors have completed. Subscribers see an empty or near-empty feed. Fix: introduce a minimum threshold — wait for at least K monitors to complete before triggering publish, or publish on a polling interval rather than a single post-spawn trigger.

Variants

VariantModificationWhen to use
Threshold-Gated Publish Publish step waits for at least K instances to complete before triggering Minimum coverage is required for the feed to be useful; full synchronization is unnecessary
Rolling Publish Feed is published on a fixed interval (every 30s) rather than triggered once Subscribers poll frequently; publish frequency matters more than event-driven triggering
Prioritized Spawn High-priority sources spawn first; lower-priority sources spawn after Source quality is heterogeneous; early-completing high-value sources should dominate the initial feed state

Related Patterns

PatternRelationship
60.62 MI Design-TimeThe synchronized counterpart — use when all instances must complete before proceeding
60.63 MI RuntimeWhen instance count is determined at runtime rather than design time
60.64 MI No RuntimeWhen instance count is not known even at execution start — dynamic creation
10.11 PipelineIf monitor results feed into a sequential post-processing chain, wrap with a Pipeline