**High-level approach**- Central Scheduler maintains DAG, worker pool, retry policies, and stable-failure aggregation.- Workers execute test tasks, report status and flaky evidence.- Retry manager applies intelligent backoff and quarantines truly flaky tests.- Aggregator consolidates final stable-failure report (tests failing consistently across retries and workers).**Components**- Scheduler: dependency resolution, task assignment, concurrency limits.- Worker: fetch task, run test, capture logs/metrics, send outcome.- Retry Manager: per-test state (attempts, last-fail-timestamp, flaky-score).- Aggregator: combine results, mark stable vs flaky.**Scheduler pseudocode**python
# simplified Python-like pseudocode
class Scheduler:
def __init__(self, dag, workers, retry_policy):
self.dag = dag # nodes: tests, edges: dependencies
self.ready = set(nodes with no unmet deps)
self.inflight = {}
self.results = {}
self.retry_policy = retry_policy
def schedule_loop(self):
while not done():
for worker in available_workers():
task = select_ready_test()
if task:
assign(worker, task)
self.inflight[task.id] = worker.id
handle_reports()
sleep(short_interval)
def handle_reports(self):
for report in collect_reports():
self.inflight.pop(report.test_id, None)
if report.status == "PASS":
mark_done(report.test_id)
else:
decision = RetryManager.decide(report.test_id, report)
if decision.retry:
enqueue_with_backoff(report.test_id, decision.delay)
else:
mark_failed(report.test_id, stable=decision.stable)
**Retry & failure semantics**- RetryManager tracks attempt_count, failure_variance, worker_affinity.- Intelligent retry rules: - Quick re-run on different worker if environment-specific failure suspected. - Exponential backoff between retries. - Stop retry when failure is reproduced N times across different workers -> mark stable. - If failure appears flaky (passes after 1-2 retries, high variance), mark flaky and quarantine test for deeper investigation.**Worker responsibilities**- Pull task, provision environment, run test with timeout, collect exit code, logs, screenshots.- Attach meta: environment id, container image, resource metrics.- Return structured report: status, artifacts, nondeterminism signals (timing, network errors).**Aggregation & reporting**- Aggregator merges attempts: stable-failure if >= M failures across K distinct environments/workers.- Report includes: final status, attempt history, logs links, flaky probability score, suggested owner.**Scalability & resilience**- Use distributed queue (e.g., Kafka/RabbitMQ), persistent state store (etcd/Postgres), idempotent assignments, leader election for scheduler HA, and heartbeat-based worker liveness.