fix: improve http connection pooling for smtp notifications #20605
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spikecurtis
reviewed
Nov 10, 2025
cli/exp_scaletest_notifications.go
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| smtpHTTPTransport := &http.Transport{ | ||
| MaxConnsPerHost: 512, | ||
| MaxIdleConnsPerHost: 512, | ||
| MaxIdleConns: 2048, |
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What's the purpose of setting both this and a per-host value?
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That was left over from my earlier tests. I forgot that MaxIdleConns is unlimited by default, so MaxIdleConnsPerHost is enough. Fixed.
spikecurtis
approved these changes
Nov 10, 2025
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This change updates how SMTP notifications are polled during scale tests.
Before, each of the ~2,000 pollers created its own http.Client, which opened thousands of short-lived TCP connections.
Under heavy load, this ran out of available network ports and caused errors like
connect: cannot assign requested addressNow, all pollers share one HTTP connection pool. This prevents port exhaustion and makes polling faster and more stable.
If a network error happens, the poller will now retry instead of stopping, so tests keep running until all notifications are received.
The
SMTPRequestTimeoutis now applied per request using a context, instead of being set on thehttp.Client.