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https://issues.apache.org/jira/browse/HDFS-9341?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15034868#comment-15034868
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Lei (Eddy) Xu commented on HDFS-9341:
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Hi, [~zhz]. Thanks for working on this. This is an interesting patch and it
looks good overall. A few small comments
* {code}
byte readSimulatedByte(Block b, long offsetInBlk, boolean slowness) ;
{code}
Should it be private? also {{slowness}} is already a member of
{{SimulatedInputStream}}, perhaps we do not need to pass it here.
* {code}
SimulatedInputStream(long l, Block b, boolean slow) {
{code}
Could you update the comments of {{SimulatedInputStream(...)}} to reflect the
parameters.
* {{private boolean randomDiskSlowness;}} should be final.
* Should {{SLOWNESS_PROBABILITY}} and {{SLOWNESS_DELAY_MS }} be configurable?
For example, control "how slow" it is? We can do it in a following JIRA. You
mentioned that
bq. The slowness can be random or controlled at certain bytes.
Are you going to implement these features in this patch?
Last, a general question: using {{random}} to build slow I/Os is
non-deterministic. Would it cause problems in unit tests?
Thanks!
> Simulated slow disk in SimulatedFSDataset
> -----------------------------------------
>
> Key: HDFS-9341
> URL: https://issues.apache.org/jira/browse/HDFS-9341
> Project: Hadoop HDFS
> Issue Type: Test
> Components: test
> Affects Versions: 2.7.1
> Reporter: Zhe Zhang
> Assignee: Zhe Zhang
> Priority: Minor
> Attachments: HDFS-9341.00.patch
>
>
> Besides simulating the byte content, {{SimulatedFSDataset}} can also simulate
> the scenario where disk is slow when accessing certain bytes. The slowness
> can be random or controlled at certain bytes. It can also be made
> configurable.
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