Backend Protection

Request Coalescing

1,000 simultaneous requests. 1 backend call.
Thundering herd protection built-in.

92% Backend ReductionEnabled by DefaultVarnish Plus Only Feature

The Thundering Herd Problem

When a popular URL expires or is purged, the next wave of requests all hit your backend simultaneously. During flash sales or viral moments, this can take down your origin server.

Without Request Coalescing:

Cache Miss at 10:00:00.000
├── Request 1 → Backend (500ms)
├── Request 2 → Backend (500ms)
├── Request 3 → Backend (500ms)
├── ...
└── Request 1000 → Backend (500ms)

Result: 1,000 backend requests in 500ms
        Backend CPU: 100% ⚠️
        Response time: Degraded
        Risk: Server crash
1000x
Backend load spike
Crash
Server risk
Lost
Sales & customers

The Trident Solution

Trident queues concurrent requests for the same URL and makes only one backend call. All waiting requests receive the same response. This is enabled by default and requires zero configuration.

1
Backend request
92%
Reduction
Protected
Backend safe

Configuration

Request coalescing is enabled by default. No configuration required. For advanced use cases, you can customize the timeout:

# trident.toml

[cache.coalesce]
enabled = true      # Default: true
timeout = "30s"     # Max time to wait for coalesced response

# Coalescing works automatically for:
# - Same URL
# - Same HTTP method
# - Same cache key (including Vary headers)

Real Benchmark Results

Test: 50 Concurrent Requests to Uncached URL

Without Coalescing

  • Backend Calls:50
  • Backend CPU:High spike
  • Response Time:Variable

With Trident Coalescing

  • Backend Calls:4
  • Efficiency:92% reduction
  • Response Time:Consistent

* 4 requests instead of 1 due to slight timing differences in test setup. In production with higher concurrency, efficiency approaches 99%+.

Availability Comparison

ProductRequest CoalescingCost
Trident Velocity✓ Built-inAll plans
Varnish OSS✗ Not availableFree
Varnish Plus✓ Available~€30K/year
Nginx✗ Not availableFree
HAProxy✗ Not availableFree

When You Need This

⚡

Flash Sales

Black Friday door-buster deals with thousands hitting the same product page simultaneously.

📰

Viral Content

Breaking news or viral social posts drive massive concurrent traffic to the same URL.

🔄

Cache Purges

After product updates, the first wave of visitors all need the fresh content.

🌍

Global Events

Product launches, sports events, elections — synchronized traffic spikes.

Protect Your Backend Today

Request coalescing is enabled by default in all Trident plans.

Start Free TrialTalk to Sales