taklwu opened a new pull request, #11102:
URL: https://github.com/apache/ozone/pull/11102

   …ently
   
   - introduced ozone.fs.synchronize.positioned.reads.enabled
   - use cursor editor to assist this change.
   
   ## What changes were proposed in this pull request?
   Provide a one-liner summary of the changes in the PR **Title** field above.
   It should be in the form of `HDDS-1234. Short summary of the change`.
   
   Please describe your PR in detail:
   * adding a new opt-in feature ozone.fs.synchronize.positioned.reads.enabled 
for concurrently positional read for multi-threads reuse the same inputstream 
like hbase pread to access the same input stream without race condition. 
   one of the problem without thread-safe inputstream, checksum may fail 
because the offset has moved from the current position. 
   
   note that hadoop's 
[FSInputStream](https://github.com/apache/hadoop/blob/trunk/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/FSInputStream.java#L73-L89)
 does have this `synchronized` block and make sure the input stream is 
thread-safe.
   
   ## What is the link to the Apache JIRA
   
   https://issues.apache.org/jira/browse/HDDS-15424
   
   ## How was this patch tested?
   1. provided unit tests
   2. tested again on a HBase's Regionserver with this change, and we don't see 
the checksum error as reported, but I found the max RPS drop from 11k to 6.8k, 
so making this feature as default optional 
   


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