[jira] [Created] (IMPALA-9479) Include GC time in runtime profiles

["Sahil Takiar (Jira)" <ji...@apache.org>]

Sahil Takiar created IMPALA-9479:
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             Summary: Include GC time in runtime profiles
                 Key: IMPALA-9479
                 URL: https://issues.apache.org/jira/browse/IMPALA-9479
             Project: IMPALA
          Issue Type: Task
            Reporter: Sahil Takiar


The JvmPauseMonitor prints out logs whenever it detects an excessive amount of time being spent in GC. However, these log lines can often go unnoticed, it would be useful to include some GC related information in the runtime profiles.

This is useful for diagnosing:
 * Issues with Java UDFs that spend a lot of time in GC
 * GC issues on the Coordinator from the fe/ code
 * Some S3 operations could potentially be GC intensive - e.g. S3A block output stream

I'm not sure there is a way to track GC per query, since GC happens globally inside the JVM. There are a few ways to get GC information into the profile:
 * If the JvmPauseMonitor detects a GC pause it can insert a warning in the profiles of all running queries
 * JMX metrics can be used to detect how much time was spent in GC from when a fragment began to when it ended



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