[Serverless] Improve the adaptive flush strategy of the serverless extension #11166
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nhinsch
previously approved these changes
Mar 4, 2022
tianchu
reviewed
Mar 7, 2022
| // something reliable. | ||
| if len(d.lastInvocations) < 3 { | ||
| // with less than 20 invocations, we may switch to periodical flushing prematurely. | ||
| if len(d.lastInvocations) < 20 { |
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How about line 75? if freq.Seconds() < 60*5, could/should we also tighten up that rule? Delaying metric for 5 mins is not a good idea to me. The only reason we want the periodic flushing instead of the per invocation flushing is to avoid hefty cost overhead, but according to my estimates, flushing once per minute, assuming the flushing adds 1s duration, with memorysize 1GB, the cost overhead < $1/month.
nhinsch
reviewed
Mar 7, 2022
nhinsch
reviewed
Mar 7, 2022
| assert.Equal((&flush.AtTheEnd{}).String(), d.AutoSelectStrategy().String(), "not the good strategy has been selected") | ||
| assert.True(d.StoreInvocationTime(now.Add(-time.Second * 70))) | ||
| assert.True(d.StoreInvocationTime(now.Add(time.Second * 19))) | ||
| assert.Equal((&flush.AtTheEnd{}).String(), d.AutoSelectStrategy().String(), "not the good strategy has been selected") | ||
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| // add a third invocation, after this, we have enough data to decide to switch |
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Looks like this comment is out of date now, probably best to just remove it and let the code speak for itself.
nhinsch
reviewed
Mar 7, 2022
| @@ -87,15 +93,14 @@ func TestInvocationInterval(t *testing.T) { | |||
| // first scenario, validate that we're not computing the interval if we only have 2 invocations done | |||
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Likewise this comment is also wrong now
nhinsch
approved these changes
Mar 7, 2022
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What does this PR do?
Increases the amount of invocations required from for the extension to transition into a periodic flush strategy.
Motivation
Hand testing a lambda function was transitioning the extension into a periodic flush strategy too quickly since users would often times invoke the function more than 3 times. This could lead to confusion since not all invocations would appear on the serverless page until reaching the flush interval of 20 seconds.
Additional Notes
Possible Drawbacks / Trade-offs
Describe how to test/QA your changes
Tested by manually deploying the extension and hand testing.
Reviewer's Checklist
Triagemilestone is set.major_changelabel if your change either has a major impact on the code base, is impacting multiple teams or is changing important well-established internals of the Agent. This label will be use during QA to make sure each team pay extra attention to the changed behavior. For any customer facing change use a releasenote.changelog/no-changeloglabel has been applied.qa/skip-qalabel is not applied.team/..label has been applied, indicating the team(s) that should QA this change.need-change/operatorandneed-change/helmlabels have been applied.