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PASSEDcache / thread_pool_exhaustion
Varnish 7.5 Thread Pool Exhausted — All Workers Busy on Debian 12 Bookworm
Varnish 7.5 has exhausted its thread pool. All worker threads are blocked on slow operations. New requests queuing indefinitely.
Pattern
TIMEOUT
Severity
HIGH
Confidence
60%
Remediation
Auto-Heal
Test Results
| Metric | Expected | Actual | Result |
|---|---|---|---|
| Pattern Recognition | TIMEOUT | TIMEOUT | |
| Severity Assessment | HIGH | HIGH | |
| Incident Correlation | N/A | None | |
| Cascade Escalation | N/A | No | |
| Remediation | — | Auto-Heal — Corax resolves autonomously |
Scenario Conditions
Debian 12 Bookworm. Varnish 7.5 thread pool at 369/369. All threads blocked on I/O. Accept queue growing. New requests timeout after 30s.
Injected Error Messages (1)
Varnish 7.5 on Debian 12 Bookworm — all worker threads busy, new requests ETIMEDOUT, timeout after 30s, thread pool 369/369 exhausted, accept queue overflow
Neural Engine Root Cause Analysis
Request timed out — service may be under heavy load, experiencing network issues, or behind a slow upstream.
Remediation Plan
Check server resource utilization (CPU/memory/disk). Investigate network path. Consider scaling if load-related.
Tested: 2026-04-02Monitors: 1 | Incidents: 1Test ID: cmnhnvc5v00v8lijggrov7736