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https://issues.apache.org/jira/browse/HADOOP-17461?focusedWorklogId=795535&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-795535
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ASF GitHub Bot logged work on HADOOP-17461:
-------------------------------------------
Author: ASF GitHub Bot
Created on: 27/Jul/22 06:55
Start Date: 27/Jul/22 06:55
Worklog Time Spent: 10m
Work Description: mehakmeet opened a new pull request, #4639:
URL: https://github.com/apache/hadoop/pull/4639
This adds a thread-level collector of IOStatistics, IOStatisticsContext,
which can be:
* Retrieved for a thread and cached for access from other
threads.
* reset() to record new statistics.
* Queried for live statistics through the
IOStatisticsSource.getIOStatistics() method.
* Queries for a statistics aggregator for use in instrumented
classes.
* Asked to create a serializable copy in snapshot()
The goal is to make it possible for applications with multiple
threads performing different work items simultaneously
to be able to collect statistics on the individual threads,
and so generate aggregate reports on the total work performed
for a specific job, query or similar unit of work.
Some changes in IOStatistics-gathering classes are needed for
this feature
* Caching the active context's aggregator in the object's
constructor
* Updating it in close()
Slightly more work is needed in multithreaded code,
such as the S3A committers, which collect statistics across
all threads used in task and job commit operations.
Currently the IOStatisticsContext-aware classes are:
* The S3A input stream, output stream and list iterators.
* RawLocalFileSystem's input and output streams.
* The S3A committers.
* The TaskPool class in hadoop-common, which propagates
the active context into scheduled worker threads.
Collection of statistics in the IOStatisticsContext
is disabled process-wide by default until the feature
is considered stable.
To enable the collection, set the option
fs.thread.level.iostatistics.enabled
to "true" in core-site.xml;
Contributed by Mehakmeet Singh and Steve Loughran
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### Description of PR
### How was this patch tested?
Region: `ap-south-1`
All tests ran successfully.
### For code changes:
- [X] Does the title or this PR starts with the corresponding JIRA issue id
(e.g. 'HADOOP-17799. Your PR title ...')?
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endpoint declared according to the connector-specific documentation?
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Issue Time Tracking
-------------------
Worklog Id: (was: 795535)
Time Spent: 10h 50m (was: 10h 40m)
> 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
> Time Spent: 10h 50m
> 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 &c 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.
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