fix: fix too short timeout causing cascading failures #4133
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the 2 second timeout on liveness probes it way too short. it is causing cascading failures when the container is busy and cannot reply immediately. this is especially bad if you have cpu limits configured on the ray pods. in addition to that, TCP takes 2-3 seconds to detect a lost packet and retry. you should NEVER have a timeout below 5 seconds in any production software. Signed-off-by: morotti <[email protected]>
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Screenshot from production, this is your ray software failing in production ;) You can see the ray pod has been up for few hours and it is failing checks sporadically, because the timeout is too short. 
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Longer term, we really need to remove dependency to exec probes, I believe that once we are using HTTP probes, we can use shorter timeouts with significantly better reliability. There's a PR for using http probes (#2360), however, it's blocked on Ray unifiying health check endpoints ray-project/ray#56204 |
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| - -c | ||
| - wget -T 2 -q -O- http://localhost:52365/api/local_raylet_healthz | grep success && wget -T 10 -q -O- http://localhost:8443/api/gcs_healthz | grep success | ||
| - wget -T 10 -q -O- http://localhost:52365/api/local_raylet_healthz | grep success && wget -T 10 -q -O- http://localhost:8443/api/gcs_healthz | grep success |
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it's not enough to increase wget timeout, you need to also increase probeTimeout in the container's probe config
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btw, this is just an example manifest, you need to update the controller logic if you want to change default behavior
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Why are these changes needed?
Hello,
The 2 second timeout on liveness probes it way too short. it is causing cascading failures when the container is busy and cannot reply immediately. this is especially bad if you have cpu limits configured on the ray pods, which restricts how much cpu the container can use.
In addition to that, TCP takes 2-3 seconds to detect a lost packet and retry. You should NEVER have a timeout below 5 seconds in any production software.
Checks