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PASSEDcache / thread_pool_exhaustion
Varnish 7.5 Thread Pool Exhausted — All Workers Busy on RHEL 9
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
RHEL 9. Varnish 7.5 thread pool at 176/176. All threads blocked on I/O. Accept queue growing. New requests timeout after 30s.
Injected Error Messages (1)
Varnish 7.5 on RHEL 9 — all worker threads busy, new requests ETIMEDOUT, timeout after 30s, thread pool 176/176 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: cmnhnvc5v00v9lijg71hx4oat