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Posted to common-user@hadoop.apache.org by Edward Capriolo <ed...@gmail.com> on 2010/01/17 19:31:31 UTC

Requesting some more JMX stability

I have been using JMX to monitor hadoop. First let me say new counters
are always great. What is not so great is shifting and renaming of
already existing JMX objects and attributes.

For example, from 0.20 to 0.21 numLiveDataNodes moved numDeadDataNodes
moved from a JMX operation to a JMX attributes, and they were renamed
in the process! numLiveDataNodes -> NumLiveDataNodes

+      "NumLiveDataNodes", "NumDeadDataNodes"
-      "numLiveDataNodes", "numDeadDataNodes" };


These attributes seemed to vanish:
-    "readMetadataOpAvgTime","readMetadataOpMaxTime",
-    "readMetadataOpMinTime","readMetadataOpNumOps",

I understand the desire to get everything where it should be. 20->21
was much last drastic then 19->20, but the renaming things from

thing_a -> ThingA

between versions. This causing lots of downstream effort, and has no
benefit to the end user.