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https://issues.apache.org/jira/browse/HADOOP-17461?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Steve Loughran updated HADOOP-17461:
Description:
For effective reporting of the iostatistics of individual worker threads, we
need a thread-level context which IO components update.
* this contact needs to be passed in two background thread forming work on
behalf of a task.
* IO Components (streams, iterators, filesystems) need to update this context
statistics as they perform work
* Without double counting anything.
I imagine a ThreadLocal IOStatisticContext which will be updated in the
FileSystem API Calls. This context MUST be passed into the background threads
used by a task, so that IO is correctly aggregated.
I don't want streams, listIterators to do the updating as there is more risk
of double counting. However, we need to see their statistics if we want to know
things like "bytes discarded in backwards seeks". And I don't want to be
updating a shared context object on every read() call.
If all we want is store IO (HEAD, GET, DELETE, list performance etc) then the
FS is sufficient.
If we do want the stream-specific detail, then I propose
* caching the context in the constructor
* updating it only in close() or unbuffer() (as we do from S3AInputStream to
S3AInstrumenation)
* excluding those we know the FS already collects.
h3. important
when backporting, please follow with HADOOP-18373
was:
For effective reporting of the iostatistics of individual worker threads, we
need a thread-level context which IO components update.
* this contact needs to be passed in two background thread forming work on
behalf of a task.
* IO Components (streams, iterators, filesystems) need to update this context
statistics as they perform work
* Without double counting anything.
I imagine a ThreadLocal IOStatisticContext which will be updated in the
FileSystem API Calls. This context MUST be passed into the background threads
used by a task, so that IO is correctly aggregated.
I don't want streams, listIterators to do the updating as there is more risk
of double counting. However, we need to see their statistics if we want to know
things like "bytes discarded in backwards seeks". And I don't want to be
updating a shared context object on every read() call.
If all we want is store IO (HEAD, GET, DELETE, list performance etc) then the
FS is sufficient.
If we do want the stream-specific detail, then I propose
* caching the context in the constructor
* updating it only in close() or unbuffer() (as we do from S3AInputStream to
S3AInstrumenation)
* excluding those we know the FS already collects.
> Add thread-level IOStatistics Context
> -
>
> Key: HADOOP-17461
> URL: https://issues.apache.org/jira/browse/HADOOP-17461
> Project: Hadoop Common
> Issue Type: Sub-task
> Components: fs, fs/azure, fs/s3
>Affects Versions: 3.3.1
>Reporter: Steve Loughran
>Assignee: Mehakmeet Singh
>Priority: Major
> Labels: pull-request-available
> Fix For: 3.3.9
>
> Time Spent: 11h 20m
> Remaining Estimate: 0h
>
> For effective reporting of the iostatistics of individual worker threads, we
> need a thread-level context which IO components update.
> * this contact needs to be passed in two background thread forming work on
> behalf of a task.
> * IO Components (streams, iterators, filesystems) need to update this context
> statistics as they perform work
> * Without double counting anything.
> I imagine a ThreadLocal IOStatisticContext which will be updated in the
> FileSystem API Calls. This context MUST be passed into the background threads
> used by a task, so that IO is correctly aggregated.
> I don't want streams, listIterators to do the updating as there is more
> risk of double counting. However, we need to see their statistics if we want
> to know things like "bytes discarded in backwards seeks". And I don't want to
> be updating a shared context object on every read() call.
> If all we want is store IO (HEAD, GET, DELETE, list performance etc) then the
> FS is sufficient.
> If we do want the stream-specific detail, then I propose
> * caching the context in the constructor
> * updating it only in close() or unbuffer() (as we do from S3AInputStream to
> S3AInstrumenation)
> * excluding those we know the FS already collects.
> h3. important
> when backporting, please follow with HADOOP-18373
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