Timeout Select errors by up to 1s to avoid callers pinning CPU and filling /var/log

[mdhoff-ms]

I have noticed two instances of filled /var/log on DUTs with many repeated lines:

2026 Jul 21 01:47:00.605758 ERR caclmgrd: :- poll_descriptors: readData error: Unable to read redis reply
2026 Jul 21 01:47:00.605776 ERR healthd: :- poll_descriptors: readData error: Unable to read redis reply
2026 Jul 21 01:47:00.605793 ERR featured: :- poll_descriptors: readData error: Unable to read redis reply

these repeat immediately, leading to /var/log partition being filled very quickly. It seems that the error case of common/select.cpp (e.g. if redis is down) returns immediately, leading to callers who call in loops spinning indefinitely and filling the log partition.

To fix this I propose the following change:
On the Select::ERROR path, we should enforce the timeout requested by the caller (often 1ms, 100ms, etc) up to a cap of 1 second, to avoid pinning the CPU in a hot loop. Additionally the readData error log should be rate limited to once per second, to avoid flooding /var/log/syslog and filling the partition.

[mssonicbld]

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[Copilot]

Pull request overview

This PR updates the core swss::Select event loop implementation to throttle repeated Select::ERROR returns, reducing CPU pinning and runaway log growth when underlying selectables (e.g., Redis-backed ones) repeatedly fail to readData().

Changes:

• Adds a 1-second backoff when Select::select() returns Select::ERROR.
• Refactors the early-return logic in Select::select() to make return conditions more explicit.
• Adds <chrono> / <thread> includes to support the new throttling sleep.

[mssonicbld]

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[mssonicbld]

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[mdhoff-ms]

maybe a good idea is to sleep only for the timeout that's passed in, then add a separate backoff (equal to 1s) to the actual logging statement. This would preserve the exact contract the caller is expecting while also mitigating the log spam.

[mssonicbld]

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