S3A S3Guard tests to skip if S3-CSE are enabled (#3263)
Follow on to
* HADOOP-13887. Encrypt S3A data client-side with AWS SDK (S3-CSE)
If the S3A bucket is set up to use S3-CSE encryption, all tests which turn
on S3Guard are skipped, so they don't raise any exceptions about
incompatible configurations.
Contributed by Mehakmeet Singh
Change-Id: I9f4188109b56a1f4e5a31fae265d980c5795db1e
This (big!) patch adds support for client side encryption in AWS S3,
with keys managed by AWS-KMS.
Read the documentation in encryption.md very, very carefully before
use and consider it unstable.
S3-CSE is enabled in the existing configuration option
"fs.s3a.server-side-encryption-algorithm":
fs.s3a.server-side-encryption-algorithm=CSE-KMS
fs.s3a.server-side-encryption.key=<KMS_KEY_ID>
You cannot enable CSE and SSE in the same client, although
you can still enable a default SSE option in the S3 console.
* Filesystem list/get status operations subtract 16 bytes from the length
of all files >= 16 bytes long to compensate for the padding which CSE
adds.
* The SDK always warns about the specific algorithm chosen being
deprecated. It is critical to use this algorithm for ranged
GET requests to work (i.e. random IO). Ignore.
* Unencrypted files CANNOT BE READ.
The entire bucket SHOULD be encrypted with S3-CSE.
* Uploading files may be a bit slower as blocks are now
written sequentially.
* The Multipart Upload API is disabled when S3-CSE is active.
Contributed by Mehakmeet Singh
Change-Id: Ie1a27a036a39db66a67e9c6d33bc78d54ea708a0
* CredentialProviderFactory to detect and report on recursion.
* S3AFS to remove incompatible providers.
* Integration Test for this.
Contributed by Steve Loughran.
Change-Id: Ia247b3c9fe8488ffdb7f57b40eb6e37c57e522ef
Fixes the regression caused by HADOOP-17511 by moving where the
option fs.s3a.acl.default is read -doing it before the RequestFactory
is created.
Adds
* A unit test in TestRequestFactory to verify the ACLs are set
on all file write operations.
* A new ITestS3ACannedACLs test which verifies that ACLs really
do get all the way through.
* S3A Assumed Role delegation tokens to include the IAM permission
s3:PutObjectAcl in the generated role.
Contributed by Steve Loughran
Change-Id: I3abac6a1b9e150b6b6df0af7c2c70093f8f518cb
This patch cuts down the size of directory trees used for
distcp contract tests against object stores, so making
them much faster against distant/slow stores.
On abfs, the test only runs with -Dscale (as was the case for s3a already),
and has the larger scale test timeout.
After every test case, the FileSystem IOStatistics are logged,
to provide information about what IO is taking place and
what it's performance is.
There are some test cases which upload files of 1+ MiB; you can
increase the size of the upload in the option
"scale.test.distcp.file.size.kb"
Set it to zero and the large file tests are skipped.
Contributed by Steve Loughran.
This improves error handling after multiple failures reading data
-when the read fails and attempts to reconnect() also fail.
Contributed by Bobby Wang.
Change-Id: If17dee395ad6b9b7c738021bad20d0a13eb4011e
This work
* Defines the behavior of FileSystem.copyFromLocal in filesystem.md
* Implements a high performance implementation of copyFromLocalOperation
for S3
* Adds a contract test for the operation: AbstractContractCopyFromLocalTest
* Implements the contract tests for Local and S3A FileSystems
Contributed by: Bogdan Stolojan
Change-Id: I25d502102775c3626c4264e5a14c649879730050
Some network exceptions can raise SdkClientException with message
`Data read has a different length than the expected`.
These should be recoverable.
Contributed by Bogdan Stolojan
Change-Id: Ia22fd77d90971e9e02b4f947398a4749eebe5909
This addresses the regression in Hadoop 3.3.1 where if no S3 endpoint
is set in fs.s3a.endpoint, S3A filesystem creation may fail on
non-EC2 deployments, depending on the local host environment setup.
* If fs.s3a.endpoint is empty/null, and fs.s3a.endpoint.region
is null, the region is set to "us-east-1".
* If fs.s3a.endpoint.region is explicitly set to "" then the client
falls back to the SDK region resolution chain; this works on EC2
* Details in troubleshooting.md, including a workaround for Hadoop-3.3.1+
* Also contains some minor restructuring of troubleshooting.md
Contributed by Steve Loughran.
Change-Id: Ife482cff513307cd52d59eec56beac0a33e031f5
The S3A connector supports
"an auditor", a plugin which is invoked
at the start of every filesystem API call,
and whose issued "audit span" provides a context
for all REST operations against the S3 object store.
The standard auditor sets the HTTP Referrer header
on the requests with information about the API call,
such as process ID, operation name, path,
and even job ID.
If the S3 bucket is configured to log requests, this
information will be preserved there and so can be used
to analyze and troubleshoot storage IO.
Contributed by Steve Loughran.
Change-Id: Ic0a105c194342ed2d529833ecc42608e8ba2f258
The option `fs.s3a.endpoint.region` can be used
to explicitly set the AWS region of a bucket.
This is needed when using AWS Private Link, as
the region cannot be automatically determined.
Contributed by Mehakmeet Singh
Change-Id: I4b52f85d7af0ddd56b2b0505ac0124d4fcc67ca0
When the S3A and ABFS filesystems are closed,
their IOStatistics are logged at debug in the log:
org.apache.hadoop.fs.statistics.IOStatisticsLogging
Set `fs.iostatistics.logging.level` to `info` for the statistics
to be logged at info. (also: `warn` or `error` for even higher
log levels).
Contributed by: Mehakmeet Singh
Change-Id: I56d44ad89fc1c0dd4baf701681834e7fd96c544f
Followup to HADOOP-13327, which changed S3A output stream hsync/hflush calls
to raise an exception.
Adds a new option fs.s3a.downgrade.syncable.exceptions
When true, calls to Syncable hsync/hflush on S3A output streams will
log once at warn (for entire process life, not just the stream), then
increment IOStats with the relevant operation counter
With the downgrade option false (default)
* IOStats are incremented
* The UnsupportedOperationException current raised includes a link to the
JIRA.
Contributed by Steve Loughran.
Change-Id: I967e077eda1d1a1a3795b4d22e003fe7997b6679
Also fixes HADOOP-16995. ITestS3AConfiguration proxy tests failures when bucket probes == 0
The improvement should include the fix, because the test would fail by default otherwise.
Change-Id: I9a7e4b5e6d4391ebba096c15e84461c038a2ec59
A regression caused by HADOOP-17022: the reduction in LIST calls broken an assertion.
Contributed by Mukund Thakur
Change-Id: Ib9725165906931634567fd1f62a81e3a6ea5620c
Moves to the builder API for AWS S3 client creation, and
offers a similar style of API to the S3A FileSystem and tests, hiding
the details of which options are client, which are in AWS Conf,
and doing the wiring up of S3A statistics interfaces to the AWS
SDK internals. S3A Statistics, including IOStatistics, should now
count throttling events handled in the AWS SDK itself.
This patch restores endpoint determination by probes to US-East-1
if the client isn't configured with fs.s3a.endpoint.
Explicitly setting the endpoint will save the cost of these probe
HTTP requests.
Contributed by Steve Loughran.
Change-Id: Ifa6caa8ff56369ad30e4fd01a42bc74f7b8b3d6b
The S3A connector's rename() operation now raises FileNotFoundException if
the source doesn't exist; a FileAlreadyExistsException if the destination
exists and is unsuitable for the source file/directory.
When renaming to a path which does not exist, the connector no longer checks
for the destination parent directory existing -instead it simply verifies
that there is no file immediately above the destination path.
This is needed to avoid race conditions with delete() and rename()
calls working on adjacent subdirectories.
Contributed by Steve Loughran.
Removed findbugs from the hadoop build images and added spotbugs instead.
Upgraded SpotBugs to 4.2.2 and spotbugs-maven-plugin to 4.2.0.
Reviewed-by: Masatake Iwasaki <iwasakims@apache.org>
(cherry picked from commit 23b343aed1)
Conflicts:
dev-support/docker/Dockerfile
hadoop-project/pom.xml
Adds an Abortable.abort() interface for streams to enable output streams to be terminated; this
is implemented by the S3A connector's output stream. It allows for commit protocols
to be implemented which commit/abort work by writing to the final destination and
using the abort() call to cancel any write which is not intended to be committed.
Consult the specification document for information about the interface and its use.
Contributed by Jungtaek Lim and Steve Loughran.
Change-Id: I7fcc25e9dd8c10ce6c29f383529f3a2642a201ae
This defines what output streams and especially those which implement
Syncable are meant to do, and documents where implementations (HDFS; S3)
don't. With tests.
The file:// FileSystem now supports Syncable if an application calls
FileSystem.setWriteChecksum(false) before creating a file -checksumming
and Syncable.hsync() are incompatible.
Contributed by Steve Loughran.
Change-Id: I892d768de6268f4dd6f175b3fe3b7e5bcaa91194
* core-default.xml updated so that fs.s3a.committer.magic.enabled = true
* CommitConstants updated to match
* All tests which previously enabled the magic committer now rely on
default settings. This helps make sure it is enabled.
* Docs cover the switch, mention its enabled and explain why you may
want to disable it.
Note: this doesn't switch to using the committer -it just enables the path
rewriting magic which it depends on.
Contributed by Steve Loughran.
This needs SPARK-33739 in the matching spark branch in order to work
Contributed by Steve Loughran.
Change-Id: I4fe75b057159e35aacc072da3cb7343467c0c3f1
Caused by HADOOP-16830 and HADOOP-17271.
Fixes tests which fail intermittently based on configs and
in the case of the HugeFile tests, bulk runs with existing
FS instances meant statistic probes sometimes ended up probing those
of a previous FS.
Contributed by Steve Loughran.
Change-Id: I65ba3f44444e59d298df25ac5c8dc5a8781dfb7d
S3A connector to support the IOStatistics API of HADOOP-16830,
This is a major rework of the S3A Statistics collection to
* Embrace the IOStatistics APIs
* Move from direct references of S3AInstrumention statistics
collectors to interface/implementation classes in new packages.
* Ubiquitous support of IOStatistics, including:
S3AFileSystem, input and output streams, RemoteIterator instances
provided in list calls.
* Adoption of new statistic names from hadoop-common
Regarding statistic collection, as well as all existing
statistics, the connector now records min/max/mean durations
of HTTP GET and HEAD requests, and those of LIST operations.
Contributed by Steve Loughran.
Change-Id: I182d34b6ac39e017a8b4a221dad8e930882b39cf
Contributed by Steve Loughran
The addition of deprecated S3A configuration options in HADOOP-17318
triggered a reload of default (xml resource) configurations, which breaks
tests which fail if there's a per-bucket setting inconsistent with test
setup.
Creating an S3AFS instance before creating the Configuration() instance
for test runs gets that reload out the way before test setup takes
place.
Along with the fix, extra changes in the failing test suite to fail
fast when marker policy isn't as expected, and to log FS state better.
Rather than create and discard an instance, add a new static method
to S3AFS and invoke it in test setup. This forces the load
Change-Id: Id52b1c46912c6fedd2ae270e2b1eb2222a360329
See also [SPARK-33402]: Jobs launched in same second have duplicate MapReduce JobIDs
Contributed by Steve Loughran.
Change-Id: Iae65333cddc84692997aae5d902ad8765b45772a
This adds a semaphore to throttle the number of FileSystem instances which
can be created simultaneously, set in "fs.creation.parallel.count".
This is designed to reduce the impact of many threads in an application calling
FileSystem.get() on a filesystem which takes time to instantiate -for example
to an object where HTTPS connections are set up during initialization.
Many threads trying to do this may create spurious delays by conflicting
for access to synchronized blocks, when simply limiting the parallelism
diminishes the conflict, so speeds up all threads trying to access
the store.
The default value, 64, is larger than is likely to deliver any speedup -but
it does mean that there should be no adverse effects from the change.
If a service appears to be blocking on all threads initializing connections to
abfs, s3a or store, try a smaller (possibly significantly smaller) value.
Contributed by Steve Loughran.
Change-Id: I57161b026f28349e339dc8b9d74f6567a62ce196
This patch
* fixes the inversion
* adds a precondition check
* if the commands are supplied inverted, swaps them with a warning.
This is to stop breaking any tests written to cope with the existing
behavior.
Contributed by Steve Loughran
Change-Id: I15c40863f0db0675c7d60db477cb3bf1693cae49
This fixes the S3Guard/Directory Marker Retention integration so that when
fs.s3a.directory.marker.retention=keep, failures during multipart delete
are handled correctly, as are incremental deletes during
directory tree operations.
In both cases, when a directory marker with children is deleted from
S3, the directory entry in S3Guard is not deleted, because it is still
critical to representing the structure of the store.
Contributed by Steve Loughran.
Change-Id: I4ca133a23ea582cd42ec35dbf2dc85b286297d2f
Unless you explicitly set it, the issue date of a delegation token identifier is 0, which confuses spark renewal (SPARK-33440). This patch makes sure that all S3A DT identifiers have the current time as issue date, fixing the problem as far as S3A tokens are concerned.
Contributed by Jungtaek Lim.
Change-Id: Ic80ac7895612a1aa669459c73a78a9c17ecf0c0d
This reverts changes in HADOOP-13230 to use S3Guard TTL in choosing when
to issue a HEAD request; fixing tests to compensate.
New org.apache.hadoop.fs.s3a.performance.OperationCost cost,
S3GUARD_NONAUTH_FILE_STATUS_PROBE for use in cost tests.
Contributed by Steve Loughran.
Change-Id: I418d55d2d2562a48b2a14ec7dee369db49b4e29e
S3AFileSystem.listStatus() is optimized for invocations
where the path supplied is a non-empty directory.
The number of S3 requests is significantly reduced, saving
time, money, and reducing the risk of S3 throttling.
Contributed by Mukund Thakur.
Change-Id: I7cc5f87aa16a4819e245e0fbd2aad226bd500f3f
This changes directory tree deletion so that only files are incrementally deleted
from S3Guard after the objects are deleted; the directories are left alone
until metadataStore.deleteSubtree(path) is invoke.
This avoids directory tombstones being added above files/child directories,
which stop the treewalk and delete phase from working.
Also:
* Callback to delete objects splits files and dirs so that
any problems deleting the dirs doesn't trigger s3guard updates
* New statistic to measure #of objects deleted, alongside request count.
* Callback listFilesAndEmptyDirectories renamed listFilesAndDirectoryMarkers
to clarify behavior.
* Test enhancements to replicate the failure and verify the fix
Contributed by Steve Loughran
Change-Id: I0e6ea2c35e487267033b1664228c8837279a35c7
Now skips ITestS3AEncryptionWithDefaultS3Settings.testEncryptionOverRename
when server side encryption is not set to sse:kms
Contributed by Mukund Thakur
Change-Id: Ifd83d353e9c7c6f7e1195a2c2f138d85cf876bb1
This adds an option to disable "empty directory" marker deletion,
so avoid throttling and other scale problems.
This feature is *not* backwards compatible.
Consult the documentation and use with care.
Contributed by Steve Loughran.
Change-Id: I69a61e7584dc36e485d5e39ff25b1e3e559a1958
Contributed by Steve Loughran.
Fixes a condition which can cause job commit to fail if a task was
aborted < 60s before the job commit commenced: the task abort
will shut down the thread pool with a hard exit after 60s; the
job commit POST requests would be scheduled through the same pool,
so be interrupted and fail. At present the access is synchronized,
but presumably the executor shutdown code is calling wait() and releasing
locks.
Task abort is triggered from the AM when task attempts succeed but
there are still active speculative task attempts running. Thus it
only surfaces when speculation is enabled and the final tasks are
speculating, which, given they are the stragglers, is not unheard of.
Note: this problem has never been seen in production; it has surfaced
in the hadoop-aws tests on a heavily overloaded desktop
Change-Id: I3b433356d01fcc50d88b4353dbca018484984bc8
Contributed by Steve Loughran.
S3A delegation token providers will be asked for any additional
token issuers, an array can be returned,
each one will be asked for tokens when DelegationTokenIssuer collects
all the tokens for a filesystem.
Change-Id: I1bd3035bbff98cbd8e1d1ac7fc615d937e6bb7bb
Contributed by Steve Loughran.
Move the loading to deployUnbonded (where they are required) and add a safety check when a new DT is requested
Change-Id: I03c69aa2e16accfccddca756b2771ff832e7dd58
Contributed by Mukund Thakur and Steve Loughran.
This patch ensures that writes to S3A fail when more than 10,000 blocks are
written. That upper bound still exists. To write massive files, make sure
that the value of fs.s3a.multipart.size is set to a size which is large
enough to upload the files in fewer than 10,000 blocks.
Change-Id: Icec604e2a357ffd38d7ae7bc3f887ff55f2d721a
Contributed by Steve Loughran.
The S3Guard absence warning of HADOOP-16484 has been changed
so that by default the S3A connector only logs at debug
when the connection to the S3 Store does not have S3Guard
enabled.
The option to control this log level is now
fs.s3a.s3guard.disabled.warn.level
and can be one of: silent, inform, warn, fail.
On a failure, an ExitException is raised with exit code 49.
For details on this safety feature, consult the s3guard documentation.
Change-Id: If868671c9260977c2b03b3e475b9c9531c98ce79
Contributed by Steve Loughran.
This is a successor to HADOOP-16346, which enabled the S3A connector
to load the native openssl SSL libraries for better HTTPS performance.
That patch required wildfly.jar to be on the classpath. This
update:
* Makes wildfly.jar optional except in the special case that
"fs.s3a.ssl.channel.mode" is set to "openssl"
* Retains the declaration of wildfly.jar as a compile-time
dependency in the hadoop-aws POM. This means that unless
explicitly excluded, applications importing that published
maven artifact will, transitively, add the specified
wildfly JAR into their classpath for compilation/testing/
distribution.
This is done for packaging and to offer that optional
speedup. It is not mandatory: applications importing
the hadoop-aws POM can exclude it if they choose.
Change-Id: I7ed3e5948d1e10ce21276b3508871709347e113d
Contributed by Mukund Thakur.
If you set the log org.apache.hadoop.fs.s3a.impl.NetworkBinding
to DEBUG, then when the S3A bucket probe is made -the DNS address
of the S3 endpoint is calculated and printed.
This is useful to see if a large set of processes are all using
the same IP address from the pool of load balancers to which AWS
directs clients when an AWS S3 endpoint is resolved.
This can have implications for performance: if all clients
access the same load balancer performance may be suboptimal.
Note: if bucket probes are disabled, fs.s3a.bucket.probe = 0,
the DNS logging does not take place.
Change-Id: I21b3ac429dc0b543f03e357fdeb94c2d2a328dd8
Contributed by Mukund Thakur
Optimize S3AFileSystem.listLocatedStatus() to perform list
operations directly and then fallback to head checks for files
Change-Id: Ia2c0fa6fcc5967c49b914b92f41135d07dab0464
add unit test, new ITest and then fix the issue: different schema, bucket == skip
factored out the underlying logic for unit testing; also moved
maybeAddTrailingSlash to S3AUtils (while retaining/forwarnding existing method
in S3AFS).
tested: london, sole failure is
testListingDelete[auth=true](org.apache.hadoop.fs.s3a.ITestS3GuardOutOfBandOperations)
filed HADOOP-16853
Change-Id: I4b8d0024469551eda0ec70b4968cba4abed405ed
Contributed by Ben Roling.
ETag values are unpredictable with some S3 encryption algorithms.
Skip ITestS3AMiscOperations tests which make assertions about etags
when default encryption on a bucket is enabled.
When testing with an AWS an account which lacks the privilege
for a call to getBucketEncryption(), we don't skip the tests.
In the event of failure, developers get to expand the
permissions of the account or relax default encryption settings.
Contributed by Steve Loughran
* move qualify logic to S3AFileSystem.makeQualified()
* make S3AFileSystem.qualify() a private redirect to that
* ITestS3GuardFsShell turned off
Contributed by Steve Loughran.
Not all stores do complete validation here; in particular the S3A
Connector does not: checking up the entire directory tree to see if a path matches
is a file significantly slows things down.
This check does take place in S3A mkdirs(), which walks backwards up the list of
parent paths until it finds a directory (success) or a file (failure).
In practice production applications invariably create destination directories
before writing 1+ file into them -restricting check purely to the mkdirs()
call deliver significant speed up while implicitly including the checks.
Change-Id: I2c9df748e92b5655232e7d888d896f1868806eb0
AreContributed by Mukund Thakur.
This addresses an issue which surfaced with KMS encryption: the wrong
KMS key could be picked up in the S3 COPY operation, so
renamed files, while encrypted, would end up with the
bucket default key.
As well as adding tests in the new suite
ITestS3AEncryptionWithDefaultS3Settings,
AbstractSTestS3AHugeFiles has a new test method to
verify that the encryption settings also work
for large files copied via multipart operations.
Contributed by Sergei Poganshev.
Catches Exception instead of IOException in closeStream()
and so handle exceptions such as SdkClientException by
aborting the wrapped stream. This will increase resilience
to failures, as any which occuring during stream closure
will be caught. Furthermore, because the
underlying HTTP connection is aborted, rather than closed,
it will not be recycled to cause problems on subsequent
operations.
This adds a new option fs.s3a.bucket.probe, range (0-2) to
control which probe for a bucket existence to perform on startup.
0: no checks
1: v1 check (as has been performend until now)
2: v2 bucket check, which also incudes a permission check. Default.
When set to 0, bucket existence checks won't be done
during initialization thus making it faster.
When the bucket is not available in S3,
or if fs.s3a.endpoint points to the wrong instance of a private S3 store
consecutive calls like listing, read, write etc. will fail with
an UnknownStoreException.
Contributed by:
* Mukund Thakur (main patch and tests)
* Rajesh Balamohan (v0 list and performance tests)
* lqjacklee (HADOOP-15990/v2 list)
* Steve Loughran (UnknownStoreException support)
modified: hadoop-tools/hadoop-aws/src/main/java/org/apache/hadoop/fs/s3a/Constants.java
modified: hadoop-tools/hadoop-aws/src/main/java/org/apache/hadoop/fs/s3a/S3AFileSystem.java
modified: hadoop-tools/hadoop-aws/src/main/java/org/apache/hadoop/fs/s3a/S3ARetryPolicy.java
modified: hadoop-tools/hadoop-aws/src/main/java/org/apache/hadoop/fs/s3a/S3AUtils.java
new file: hadoop-tools/hadoop-aws/src/main/java/org/apache/hadoop/fs/s3a/UnknownStoreException.java
new file: hadoop-tools/hadoop-aws/src/main/java/org/apache/hadoop/fs/s3a/impl/ErrorTranslation.java
modified: hadoop-tools/hadoop-aws/src/site/markdown/tools/hadoop-aws/index.md
modified: hadoop-tools/hadoop-aws/src/site/markdown/tools/hadoop-aws/performance.md
modified: hadoop-tools/hadoop-aws/src/site/markdown/tools/hadoop-aws/troubleshooting_s3a.md
modified: hadoop-tools/hadoop-aws/src/test/java/org/apache/hadoop/fs/s3a/AbstractS3AMockTest.java
new file: hadoop-tools/hadoop-aws/src/test/java/org/apache/hadoop/fs/s3a/ITestS3ABucketExistence.java
modified: hadoop-tools/hadoop-aws/src/test/java/org/apache/hadoop/fs/s3a/MockS3ClientFactory.java
modified: hadoop-tools/hadoop-aws/src/test/java/org/apache/hadoop/fs/s3a/TestS3AExceptionTranslation.java
modified: hadoop-tools/hadoop-aws/src/test/java/org/apache/hadoop/fs/s3a/s3guard/AbstractS3GuardToolTestBase.java
modified: hadoop-tools/hadoop-aws/src/test/java/org/apache/hadoop/fs/s3a/s3guard/ITestS3GuardToolDynamoDB.java
modified: hadoop-tools/hadoop-aws/src/test/resources/core-site.xml
Change-Id: Ic174f803e655af172d81c1274ed92b51bdceb384
Contributed by Steve Loughran.
During S3A rename() and delete() calls, the list of objects delete is
built up into batches of a thousand and then POSTed in a single large
DeleteObjects request.
But as the IO capacity allowed on an S3 partition may only be 3500 writes
per second *and* each entry in that POST counts as a single write, then
one of those posts alone can trigger throttling on an already loaded
S3 directory tree. Which can trigger backoff and retry, with the same
thousand entry post, and so recreate the exact same problem.
Fixes
* Page size for delete object requests is set in
fs.s3a.bulk.delete.page.size; the default is 250.
* The property fs.s3a.experimental.aws.s3.throttling (default=true)
can be set to false to disable throttle retry logic in the AWS
client SDK -it is all handled in the S3A client. This
gives more visibility in to when operations are being throttled
* Bulk delete throttling events are logged to the log
org.apache.hadoop.fs.s3a.throttled log at INFO; if this appears
often then choose a smaller page size.
* The metric "store_io_throttled" adds the entire count of delete
requests when a single DeleteObjects request is throttled.
* A new quantile, "store_io_throttle_rate" can track throttling
load over time.
* DynamoDB metastore throttle resilience issues have also been
identified and fixed. Note: the fs.s3a.experimental.aws.s3.throttling
flag does not apply to DDB IO precisely because there may still be
lurking issues there and it safest to rely on the DynamoDB client
SDK.
Change-Id: I00f85cdd94fc008864d060533f6bd4870263fd84