HDFS-16678. RBF should supports disable getNodeUsage() in RBFMetrics #4606
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goiri
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Jul 21, 2022
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What is the expensive part of this whole block? this?
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I guess is rpcServer.getDatanodeReport() actually.
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Yes, rpcServer.getDatanodeReport() is expensive. As the number of DNs or downstream nameservices in the cluster increases, it will become more and more expensive. such as 1w+ DNs, 5w+ DNs, 20+ NSs, 50+ NSs.
...doop-hdfs-rbf/src/main/java/org/apache/hadoop/hdfs/server/federation/metrics/RBFMetrics.java
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Apache commons math has a nice StandardDeviation utility.
It might be good to use this directly.
https://commons.apache.org/proper/commons-math/javadocs/api-3.6/org/apache/commons/math3/stat/descriptive/moment/StandardDeviation.html
...op-hdfs-rbf/src/main/java/org/apache/hadoop/hdfs/server/federation/router/RBFConfigKeys.java
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@goiri Sir, I have updated the patch and added some UTs, please help me review it again. Thanks |
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goiri
approved these changes
Jul 24, 2022
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@goiri Hi, master, can you help me merge it into the trunk? |
slfan1989
reviewed
Jul 28, 2022
| dev = deviation.evaluate(usages); | ||
| } | ||
| } catch (IOException e) { | ||
| LOG.error("Cannot get the live nodes: {}", e.getMessage()); |
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I feel it would be better this way.
LOG.error("Cannot get the live nodes.", e).
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I feel it would be better this way.
LOG.error("Cannot get the live nodes.", e).
Do we want to have the full stack trace? I think it is pretty clear what the error is here without it.
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Thanks @slfan1989 @goiri for your review. I think e.getMessage() is enough. @slfan1989 Do you have some cases that need the full stack?
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@goiri @slfan1989 Master, can help me merge this RP into trunk? Thanks. |
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@slfan1989 please take another look |
ferhui
approved these changes
Aug 10, 2022
slfan1989
approved these changes
Aug 12, 2022
LGTM. @ZanderXu thanks for your contribution! @goiri @goiri Thanks for helping review the code! |
tomscut
approved these changes
Aug 12, 2022
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@goiri @slfan1989 @ferhui @tomscut Maters, thank you very much for helping me review this patch. |
HarshitGupta11
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Nov 28, 2022
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Description of PR
In our prod environment, we try to collect RBF metrics every 15s through jmx_exporter. And we found that collection task often failed.
After tracing and found that the collection task is blocked at getNodeUsage() in RBFMetrics, because it will collect all datanode's usage from downstream nameservices.
This is a very expensive and almost useless operation. Because in most scenarios, each downstream nameserivce contains almost the same DNs. We can get the data usage's from any one nameservices if need, not from RBF.
So I feel that RBF should supports disable getNodeUsage() in RBFMetrics.