Before You Move All Your Scrapers onto a New Proxy Network, Which Performance and Stability Checks Should You Run First?
1. Introduction: “It Works in Tests—So Why Does Production Fall Apart?”
On paper, the new proxy network looks fine.
IPs connect.
Latency looks acceptable.
Sample requests succeed.
So you flip the switch and move all scrapers over.
Then problems appear:
- success rates slowly decline
- retries spike without clear errors
- some targets degrade while others look normal
- throughput becomes unstable under real load
This is the core pain point:
most teams test proxies in isolation, but scrapers fail at system scale, not at “one request” scale.
Here is the short direction:
Before migrating scrapers, you must test not just raw performance, but behavior under concurrency, retries, and long-running load.
This article explains exactly which checks matter most, and in what order to run them, before you trust a new proxy network with production scraping.
2. Why Basic “Does It Connect?” Tests Are Misleading
A single request test answers only one question:
“Can I reach the target right now?”
It does not tell you:
- how the network behaves under sustained load
- how exits degrade over time
- how retries amplify traffic
- how routing behaves when some exits fail
- whether success rate collapses at scale
Most proxy failures happen after minutes or hours, not on the first request.
3. Check #1: Latency Distribution, Not Average Latency
3.1 Why averages lie
Average latency hides:
- long-tail slow requests
- jitter spikes
- region-specific degradation
Scrapers suffer when tail latency grows, because:
- workers block longer
- concurrency pressure increases
- retries trigger sooner
3.2 What to measure
For a realistic test, record:
- p50 / p90 / p95 / p99 latency
- latency by region or pool
- latency drift over time (15–60 minutes)
If p95/p99 grows steadily, the pool will not hold up under production load.
4. Check #2: Success Rate Under Sustained Concurrency
4.1 Burst success is not stability
Many proxy pools handle:
- small bursts
- short tests
But fail when:
- concurrency is sustained
- connections stay open
- workers run continuously
4.2 How to test properly
Run a test that matches:
- your real concurrency
- your real request rate
- your real duration (at least 30–60 minutes)
Track:
- success rate over time
- error types (timeouts vs blocks vs connection errors)
If success decays over time, exits are burning or being deprioritized.
5. Check #3: Retry Amplification Behavior
Retries are where many migrations fail.
5.1 What to observe
Measure:
- average attempts per successful request
- retry clustering (bursts of retries)
- whether retries hit new exits or the same exit
A “working” proxy network can still be dangerous if retries multiply load.
5.2 Red flags
- attempts per success steadily rising
- retries causing higher latency for later requests
- retries spreading failures across the pool
This indicates the network will become unstable at scale.
6. Check #4: Exit Churn and Route Stability
6.1 Why exit churn matters
If exits change too often:
- sessions break
- cookies lose value
- target sites see fragmented behavior
This is less visible in scraping than in logins, but it still hurts:
- pagination chains
- follow-up requests
- cache reuse
6.2 What to log
If possible, log:
- exit IP per request
- exit change frequency
- correlation between exit changes and failures
High churn under load often explains “random” scrape failures.
7. Check #5: Pool Contamination Between Workloads
Before migrating everything, ask:
- will all scrapers share one pool?
- are different targets mixed together?
- do aggressive scrapers share exits with gentle ones?
7.1 Why this matters
Noisy targets can:
- burn exits faster
- increase global block rates
- degrade unrelated scrapers
Test pools per workload if possible, even temporarily, to see burn rates.
8. Check #6: Degradation and Recovery Behavior
Failures are inevitable. What matters is recovery.
8.1 Test partial failure scenarios
During testing:
- intentionally push concurrency
- allow some exits to fail
- observe how the pool recovers
Key questions:
- does success rate recover after pressure drops?
- do exits stay degraded permanently?
- does routing overreact and churn?
A pool that cannot recover will force frequent manual intervention.
9. A Simple Pre-Migration Test Plan You Can Copy
Run these tests in order:
(1) Baseline test
Low concurrency, short duration
→ verifies basic compatibility
(2) Sustained load test
Real concurrency, 30–60 minutes
→ reveals burn and drift
(3) Retry stress test
Enable normal retries
→ measures amplification risk
(4) Mixed workload test
Combine multiple targets
→ exposes pool contamination
(5) Cooldown test
Stop traffic, then resume
→ checks recovery behavior
If a proxy network passes all five, it is safe to migrate scrapers gradually.
10. Where YiLu Proxy Helps During Scraper Migration
During migration, the biggest risk is moving too much, too fast.
YiLu Proxy helps reduce that risk because:
- you can create separate pools per scraper or per target class
- noisy, experimental jobs can be isolated from stable workloads
- exit behavior is easier to observe per pool
- you can migrate scraper-by-scraper instead of all at once
A practical migration setup:
SCRAPER_TEST_POOL: new network, limited scopeSCRAPER_STABLE_POOL: existing network- shift traffic gradually and compare metrics side by side
This turns migration into an experiment instead of a gamble.
Before moving all scrapers to a new proxy network, don’t ask:
“Does it work?”
Ask:
- does it stay stable under real load?
- do retries stay under control?
- does performance degrade predictably?
- can pools be isolated and observed?
If you answer those questions first, migration becomes a measured rollout—not an outage waiting to happen.