Steve Loughran

@virajjasani done your comments; had to rebase for what turned out to be a spurious merge conflict (adjacent methods in s3afs), so you can't see exactly what changed in the...

``` ./hadoop-tools/hadoop-aws/src/test/java/org/apache/hadoop/fs/s3a/S3ATestUtils.java:997: .setPerformanceFlags(FlagSet.createFlagSet(PerformanceFlagEnum.class,FS_S3A_PERFORMANCE_FLAGS)): Line is longer than 100 characters (found 103). [LineLength] ./hadoop-tools/hadoop-aws/src/test/java/org/apache/hadoop/fs/s3a/S3ATestUtils.java:997: .setPerformanceFlags(FlagSet.createFlagSet(PerformanceFlagEnum.class,FS_S3A_PERFORMANCE_FLAGS)):77: ',' is not followed by whitespace. [WhitespaceAfter] ```

@mukund-thakur thanks, altered the tests and tried to clarify the immutability. One final thought: should we have a default list of enum values to set if, when parsing the config...

ok, everything is addressed, going to merge to the branches

Syed, not got numbers yet, though I will try to collect some before/after values

update: going to pull out the reused code into some AtomicAutoCloseable(function) which takes a supplier as an arg and invokes it if needed, call close if not. No plans to...

tested, s3 london. `-Dparallel-tests -DtestsThreadCount=10 -Dscale`. One odd failure, where an s3 request was considered to be outside of a span even though the callchain implies it was within a...

somef more changes planned in the `LazyAtomicReference` class. * implement the Supplier interface, which invokes `getUnchecked()` * plus static fromSupplier() constructor implementing supplier lets you something quite special with this:...

tested with s3 london (versioned bucket), all good except for the usual `ITestS3AConfiguration.testS3SpecificSignerOverride` region failure No performance timings except that we know that we delay creation of async and transfer...

retested s3 london `-Dparallel-tests -DtestsThreadCount=10 -Dscale -Dprefetch`, 15 minutes.