* Replace usages RandomizedTestingTask with built-in Gradle Test (#40978)
This commit replaces the existing RandomizedTestingTask and supporting code with Gradle's built-in JUnit support via the Test task type. Additionally, the previous workaround to disable all tasks named "test" and create new unit testing tasks named "unitTest" has been removed such that the "test" task now runs unit tests as per the normal Gradle Java plugin conventions.
(cherry picked from commit 323f312bbc829a63056a79ebe45adced5099f6e6)
* Fix forking JVM runner
* Don't bump shadow plugin version
Many gradle projects specifically use the -try exclude flag, because
there are many cases where auto-closeable resource ignore is never
referenced in body of corresponding try statement. Suppressing this
warning specifically in each case that it happens using
`@SuppressWarnings("try")` would be very verbose.
This change removes `-try` from any gradle project and adds it to the
build plugin. Also this change removes exclude flags from gradle projects
that is already specified in build plugin (for example -deprecation).
Relates to #40366
This commit adds an InboundHandler to handle inbound message processing.
With this commit, this code is moved out of the TcpTransport.
Additionally, finer grained unit tests are added to ensure that the
inbound processing works as expected
Currently there are some components of message serializer and sending
that still occur in TcpTransport. This commit makes it possible to
send a message without the TcpTransport by moving all of the remaining
application logic to the OutboundHandler. Additionally, it adds unit
tests to ensure that this logic works as expected.
Currently, we maintain a transport name ("mock-nio", "nio", "netty")
that is passed to a `TcpTransportChannel` when a request is received.
The value of this name is to associate with the task when we register a
task with the task manager. However, it is only possible to run ES with
one transport, so having an implementation specific name is unnecessary.
This commit removes the name and replaces it with the generic
"transport".
* Optimize Bulk Message Parsing and Message Length Parsing
* findNextMarker took almost 1ms per invocation during the PMC rally track
* Fixed to be about an order of magnitude faster by using Netty's bulk `ByteBuf` search
* It is unnecessary to instantiate an object (the input stream wrapper) and throw it away, just to read the `int` length from the message bytes
* Fixed by adding bulk `int` read to BytesReference
In integration tests where `setBootstrapMasterNodeIndex()` is used in
combination with `autoMinMasterNodes = false` the cluster can start
bootstrapping once the number of nodes set with the
`setBootstrapMasterNodeIndex` have been started but it's not ensured
that all nodes have successfully joined to form the cluster.
This behaviour was introduced with 5db7ed22a0
and in order to ensure that the cluster is properly formed before proceeding
with the integration test, use `ensureStableCluster()` with the
appropriate number of expected nodes.
Fixes: #39220
We have had various reports of problems caused by the maxRetryTimeout
setting in the low-level REST client. Such setting was initially added
in the attempts to not have requests go through retries if the request
already took longer than the provided timeout.
The implementation was problematic though as such timeout would also
expire in the first request attempt (see #31834), would leave the
request executing after expiration causing memory leaks (see #33342),
and would not take into account the http client internal queuing (see #25951).
Given all these issues, it seems that this custom timeout mechanism
gives little benefits while causing a lot of harm. We should rather rely
on connect and socket timeout exposed by the underlying http client
and accept that a request can overall take longer than the configured
timeout, which is the case even with a single retry anyways.
This commit removes the `maxRetryTimeout` setting and all of its usages.
With this change we no longer support pluggable discovery implementations. No
known implementations of `DiscoveryPlugin` actually override this method, so in
practice this should have no effect on the wider world. However, we were using
this rather extensively in tests to provide the `test-zen` discovery type. We
no longer need a separate discovery type for tests as we no longer need to
customise its behaviour.
Relates #38410
Currently, there are a few tests that use autoMinMasterNodes=false and
hence override addExtraClusterBootstrapSettings, mostly this is 10-30
lines of codes that are copy-pasted from class to class.
This PR introduces `InternalTestCluster.setBootstrapMasterNodeIndex`
which is suitable for all classes and copy-paste could be removed.
Removing code is always a good thing!
Today we pass `discovery.zen.minimum_master_nodes` to nodes started up in
tests, but for 7.x nodes this setting is not required as it has no effect.
This commit removes this setting so that nodes are started with more realistic
configurations, and deprecates it.
This drops the option for tests to disable strict deprecation mode in
the low level rest client in favor of configuring expected warnings on
any calls that should expect warnings. This behavior is
paranoid-by-default which is generally the right way to handle
deprecations and tests in general.
This commit introduces a NetworkMessage class. This class has two
subclasses - InboundMessage and OutboundMessage. These messages can
be serialized and deserialized independent of the transport. This allows
more granular testing. Additionally, the serialization mechanism is now
a simple Supplier. This builds the framework to eventually move the
serialization of transport messages to the network thread. This is the
one serialization component that is not currently performed on the
network thread (transport deserialization and http serialization and
deserialization are all on the network thread).
* Default include_type_name to false for get and put mappings.
* Default include_type_name to false for get field mappings.
* Add a constant for the default include_type_name value.
* Default include_type_name to false for get and put index templates.
* Default include_type_name to false for create index.
* Update create index calls in REST documentation to use include_type_name=true.
* Some minor clean-ups around the get index API.
* In REST tests, use include_type_name=true by default for index creation.
* Make sure to use 'expression == false'.
* Clarify the different IndexTemplateMetaData toXContent methods.
* Fix FullClusterRestartIT#testSnapshotRestore.
* Fix the ml_anomalies_default_mappings test.
* Fix GetFieldMappingsResponseTests and GetIndexTemplateResponseTests.
We make sure to specify include_type_name=true during xContent parsing,
so we continue to test the legacy typed responses. XContent generation
for the typeless responses is currently only covered by REST tests,
but we will be adding unit test coverage for these as we implement
each typeless API in the Java HLRC.
This commit also refactors GetMappingsResponse to follow the same appraoch
as the other mappings-related responses, where we read include_type_name
out of the xContent params, instead of creating a second toXContent method.
This gives better consistency in the response parsing code.
* Fix more REST tests.
* Improve some wording in the create index documentation.
* Add a note about types removal in the create index docs.
* Fix SmokeTestMonitoringWithSecurityIT#testHTTPExporterWithSSL.
* Make sure to mention include_type_name in the REST docs for affected APIs.
* Make sure to use 'expression == false' in FullClusterRestartIT.
* Mention include_type_name in the REST templates docs.
This commit modifies ESSingleNodeTestCase and ESIntegTestCase and
several concrete test classes to use node names when bootstrapping the
cluster.
Today ClusterBootstrapService.INITIAL_MASTER_NODE_COUNT_SETTING
setting is used to bootstrap clusters in tests. Instead, we want to use
ClusterBootrstapService.INITIAL_MASTER_NODES_SETTING and get rid of
the former setting eventually.
There were two main problems when refactoring InternalTestCluster:
1. Nodes are created one-by-one in buildNode method. And node.name
is created in this method as well. It's not suitable for bootstrapping,
because we need to have the names of all master eligible nodes in
advance, before creating the node with bootstrapping configuration set.
We address this issue by separating buildNode into two methods:
getNodeSettings and buildNode. We first iterate over all nodes to
get nodes settings, then change the setting for the bootstrapping node
and then proceed with building the node.
2. If autoManageMinMasterNodes = false, there is no way for the test to
set the list of bootstrapping nodes because node names are not known in
advance. This problem is solved by adding updateNodesSettings method
to NodeConfigurationSource and ESIntegTestCase (which could be
overridden by concrete integration test class). Once we have the list
of settings for all nodes, the integration test class is allowed to
update it. In our case, we update the
ClusterBootrstapService.INITIAL_MASTER_NODES_SETTING setting.
This change adds a new untyped endpoint `{index}/_source/{id}` for both the
GET and the HEAD methods to get the source of a document or check for its
existance. It also adds deprecation warnings to RestGetSourceAction that emit
a warning when the old deprecated "type" parameter is still used. Also updating
documentation and tests where appropriate.
Relates to #35190
This commit updates our transport settings for 7.0. It generally takes a
few approaches. First, for normal transport settings, it usestransport.
instead of transport.tcp. Second, it uses transport.tcp, http.tcp,
or network.tcp for all settings that are proxies for OS level socket
settings. Third, it marks the network.tcp.connect_timeout setting for
removal. Network service level settings are only settings that apply to
both the http and transport modules. There is no connect timeout in
http. Fourth, it moves all the transport settings to a single class
TransportSettings similar to the HttpTransportSettings class.
This commit does not actually remove any settings. It just adds the new
renamed settings and adds todos for settings that will be deprecated.
`PageCacheRecycler` is the class that creates and holds pages of arrays
for various uses. `BigArrays` is just one user of these pages. This
commit moves the constants that define the page sizes for the recycler
to be on the recycler class.
Currently our handshake requests do not include a version. This is
unfortunate as we cannot rely on the stream version since it is not the
sending node's version. Instead it is the minimum compatibility version.
The handshake request is currently empty and we do nothing with it. This
should allow us to add data to the request without breaking backwards
compatibility.
This commit adds the version to the handshake request. Additionally, it
allows "future data" to be added to the request. This allows nodes to craft
a version compatible response. And will properly handle additional data in
future handshake requests. The proper handling of "future data" is useful
as this is the only request where we do not know the other node's version.
Finally, it renames the TcpTransportHandshaker to
TransportHandshaker.
This commit modifies BigArrays to take a circuit breaker name and
the circuit breaking service. The default instance of BigArrays that
is passed around everywhere always uses the request breaker. At the
network level, we want to be using the inflight request breaker. So this
change will allow that.
Additionally, as this change moves away from a single instance of
BigArrays, the class is modified to not be a Releasable anymore.
Releasing big arrays was always dispatching to the PageCacheRecycler,
so this change makes the PageCacheRecycler the class that needs to be
managed and torn-down.
Finally, this commit closes#31435 be making the serialization of
transport messages use the inflight request breaker. With this change,
we no longer push the global BigArrays instnace to the network level.
By default gateway.recover_after_master_nodes is set to
discovery.zen.minimum_master_nodes but in this Zen2 test this is set to an
unreasonably large value. This change updates it so the cluster can properly
form.
Today, we allow all nodes in an integration test to bootstrap. However this
seems to lead to test failures due to post-election instability. The change
avoids this instability by only bootstrapping a single node in the cluster.
This commit upgrades netty. This will close#35360. Netty started
throwing an IllegalArgumentException if a CompositeByteBuf is
created with < 2 components. Netty4Utils was updated to reflect this
change.
This is related to #34405 and a follow-up to #34753. It makes a number
of changes to our current keepalive pings.
The ping interval configuration is moved to the ConnectionProfile.
The server channel now responds to pings. This makes the keepalive
pings bidirectional.
On the client-side, the pings can now be optimized away. What this
means is that if the channel has received a message or sent a message
since the last pinging round, the ping is not sent for this round.
* [Zen2] Implement Tombstone REST APIs
* Adds REST API for withdrawing votes and clearing vote withdrawls
* Tests added to Netty4 module since we need a real Network impl. for Http endpoints
This commit removes the dedicated `setSoLinger` method. This simplifies
the `TcpChannel` interface. This method has very little effect as the
SO_LINGER is not set prior to the channels being closed in the abstract
transport test case. We still will set SO_LINGER on the
`MockNioTransport`. However we can do this manually.
This pull request makes the `RestGetSourceAction` return a `ResourceNotFoundException` with a proper JSON response when source or document itself is missing (see issue #33384).
Here is below a sample JSON output:
```
{
"error": {
"root_cause": [
{
"type": "resource_not_found_exception",
"reason": "Source not found [index1]/[_doc]/[1]"
}
],
"type": "resource_not_found_exception",
"reason": "Source not found [index1]/[_doc]/[1]"
},
"status": 404
}
```
This is related to #34483. It introduces a namespaced setting for
compression that allows users to configure compression on a per remote
cluster basis. The transport.tcp.compress remains as a fallback
setting. If transport.tcp.compress is set to true, then all requests
and responses are compressed. If it is set to false, only requests to
clusters based on the cluster.remote.cluster_name.transport.compress
setting are compressed. However, after this change regardless of any
local settings, responses will be compressed if the request that is
received was compressed.
This is related to #29023. Additionally at other points we have
discussed a preference for removing the need to unnecessarily block
threads for opening new node connections. This commit lays the groudwork
for this by opening connections asynchronously at the transport level.
We still block, however, this work will make it possible to eventually
remove all blocking on new connections out of the TransportService
and Transport.
Currently we create a new netty event loop group for client connections
and all server profiles. Each new group creates new threads for io
processing. This means 2 * num of processors new threads for each group.
A single group should be able to handle all io processing (for the
transports). This also brings the netty module inline with what we do
for nio.
Additionally, this PR renames the worker threads to be the same for
netty and nio.
With this commit we differentiate between permanent circuit breaking
exceptions (which require intervention from an operator and should not
be automatically retried) and transient ones (which may heal themselves
eventually and should be retried). Furthermore, the parent circuit
breaker will categorize a circuit breaking exception as either transient
or permanent based on the categorization of memory usage of its child
circuit breakers.
Closes#31986
Relates #34460
In order to remove Streamable from the codebase, Response objects need
to be read using the Writeable.Reader interface which this change
enables. This change enables the use of Writeable.Reader by adding the
`Action#getResponseReader` method. The default implementation simply
uses the existing `newResponse` method and the readFrom method. As
responses are migrated to the Writeable.Reader interface, Action
classes can be updated to throw an UnsupportedOperationException when
`newResponse` is called and override the `getResponseReader` method.
Relates #34389
This is related to #30876. The AbstractSimpleTransportTestCase initiates
many tcp connections. There are normally over 1,000 connections in
TIME_WAIT at the end of the test. This is because every test opens at
least two different transports that connect to each other with 13
channel connection profiles. This commit modifies the default
connection profile used by this test to 6. One connection for each
type, except for REG which gets 2 connections.
The contains syntax was added in #30874 but the skips were not properly
put in place.
The java runner has the feature so the tests will run as part of the
build, but language clients will be able to support it at their own
pace.
Currently a bad regex in CORS settings throws a PatternSyntaxException, which
then bubbles up through the bootstrap code, meaning users have to parse a
stack trace to work out where the problem is. We should instead catch this
exception and rethrow with a more useful error message.
This commit introduces an AbstractSimpleSecurityTransportTestCase for
security transports. This classes provides transport tests that are
specific for security transports. Additionally, it fixes the tests referenced in
#33285.
Historically we have had a ESLoggingHandler in the netty module that
logs low-level connection operations. This class just extends the netty
logging handler with some (broken) message deserialization. This commit
fixes this message serialization and moves the class to server.
This new logger logs inbound and outbound messages. Eventually, we
should move other event logging to this class (connect, close, flush).
That way we will have consistent logging regards of which transport is
loaded.
Resolves#27306 on master. Older branches will need a different fix.
This commit is related to #32517. It allows an "server_name"
attribute on a DiscoveryNode to be propagated to the server using
the TLS SNI extentsion. This functionality is only implemented for
the netty security transport.
- third party audit detects jar hell with JDK so we disable it
- jdk non portable in forbiddenapis detects classes being used from the
JDK ( for fips ) that are not portable, this is intended so we don't
scan for it on fips.
- different exclusion rules for third party audit on fips
Closes#33179
In #29623 we added `Request` object flavored requests to the low level
REST client and in #30315 we deprecated the old `performRequest`s. In a
long series of PRs I've changed all of the old style requests that I
could find with `grep`. In this PR I change all requests that I could
find by *removing* the deprecated methods. Since this is a non-trivial
change I do not include actually removing the deprecated requests. I'll
do that in a follow up. But this should be the last set of usage
removals before the actual deprecated method removal. Yay!
In our Netty layer we have had to take extra precautions against Netty
catching throwables which prevents them from reaching the uncaught
exception handler. This code has taken on additional uses in NIO layer
and now in the scheduler engine because there are other components in
stack traces that could catch throwables and suppress them from reaching
the uncaught exception handler. This commit is a simple cleanup of the
iterative evolution of this code to refactor all uses into a single
method in ExceptionsHelper.
This is related to #32517. This commit passes the DiscoveryNode to the
initiateChannel method for different Transport implementation. This
will allow additional attributes (besides just the socket address) to be
used when opening channels.
This is a followup to #31886. After that commit the
TransportConnectionListener had to be propogated to both the
Transport and the ConnectionManager. This commit moves that listener
to completely live in the ConnectionManager. The request and response
related methods are moved to a TransportMessageListener. That listener
continues to live in the Transport class.
This is related to #31835. It moves the default connection profile into
the ConnectionManager class. The will allow us to have different
connection managers with different profiles.
This is related to #31835. This commit adds a connection manager that
manages client connections to other nodes. This means that the
TcpTransport no longer maintains a map of nodes that it is connected
to.
* Upgrade to `4.1.28` since the problem reported in #32487 is a bug in Netty itself (see https://github.com/netty/netty/issues/7337)
* Fixed other leaks in test code that now showed up due to fixes improvements in leak reporting in the newer version
* Needed to extend permissions for netty common package because it now sets a classloader at runtime after changes in 63bae0956a
* Adjusted forbidden APIs check accordingly
* Closes#32487
There are two scenarios where a http request could terminate in the cors
handler. If that occurs, the requests need to be released. This commit
releases those requests.
* Test `handler` must release buffer the same way the replaced `org.elasticsearch.http.netty4.Netty4HttpRequestHandler#channelRead0` releases it
* Closes#32289
In #29623 we added `Request` object flavored requests to the low level
REST client and in #30315 we deprecated the old `performRequest`s. This
changes most of the calls not in X-Pack to their new versions.
This is related to #27260. It adds the SecurityNioHttpServerTransport
to the security plugin. It randomly uses the nio http transport in
security integration tests.
Today TransportService is tightly coupled with Transport since it
requires an instance of TransportService in order to receive responses
and send requests. This is mainly due to the Request and Response handlers
being maintained in TransportService but also because of the lack of a proper
callback interface.
This change moves request handler registry and response handler registration into
Transport and adds all necessary methods to `TransportConnectionListener` in order
to remove the `TransportService` dependency from `Transport`
Transport now accepts one or more `TransportConnectionListener` instances that are
executed sequentially in a blocking fashion.
* remove left-over comment
* make sure of the property for plugins
* skip installing modules if these exist in the distribution
* Log the distrbution being ran
* Don't allow running with integ-tests-zip passed externally
* top level x-pack/qa can't run with oss distro
* Add support for matching objects in lists
Makes it possible to have a key that points to a list and assert that a
certain object is present in the list. All keys have to be present and
values have to match. The objects in the source list may have additional
fields.
example:
```
match: { 'nodes.$master.plugins': { name: ingest-attachment } }
```
* Update plugin and module tests to work with other distributions
Some of the tests expected that the integration tests will always be ran
with the `integ-test-zip` distribution so that there will be no other
plugins loaded.
With this change, we check for the presence of the plugin without
assuming exclusivity.
* Allow modules to run on other distros as well
To match the behavior of tets.distributions
* Add and use a new `contains` assertion
Replaces the previus changes that caused `match` to do a partial match.
* Implement PR review comments
TransportRequestHandler currently contains 2 messageReceived methods,
one which takes a Task, and one that does not. The first just delegates
to the second. This commit changes all existing implementors of
TransportRequestHandler to implement the version which takes Task, thus
allowing the class to be a functional interface, and eliminating the
need to throw exceptions when a task needs to be ensured.
Historically in TcpTransport server channels were represented by the
same channel interface as socket channels. This was necessary as
TcpTransport was parameterized by the channel type. This commit
introduces TcpServerChannel and HttpServerChannel classes. Additionally,
it adds the implementations for the various transports. This allows
server channels to have unique functionality and not implement the
methods they do not support (such as send and getRemoteAddress).
Additionally, with the introduction of HttpServerChannel this commit
extracts some of the storing and closing channel work to the abstract
http server transport.
This is a general cleanup of channels and exception handling in http.
This commit introduces a CloseableChannel that is a superclass of
TcpChannel and HttpChannel. This allows us to unify the closing logic
between tcp and http transports. Additionally, the normal http channels
are extracted to the abstract server transport.
Finally, this commit (mostly) unifies the exception handling between nio
and netty4 http server transports.
This is related to #28898. This PR implements pooling of bytes arrays
when reading from the wire in the http server transport. In order to do
this, we must integrate with netty reference counting. That manner in
which this PR implements this is making Pages in InboundChannelBuffer
reference counted. When we accessing the underlying page to pass to
netty, we retain the page. When netty releases its bytebuf, it releases
the underlying pages we have passed to it.
Currently we maintain a compatibility map of http status codes in both
the netty4 and nio modules. These maps convert a RestStatus to a netty
HttpResponseStatus. However, as these fundamentally represent integers,
we can just use the netty valueOf method to convert a RestStatus to a
HttpResponseStatus.
This is related to #28898. With the addition of the http nio transport,
we now have two different modules that provide http transports.
Currently most of the http logic lives at the module level. However,
some of this logic can live in server. In particular, some of the
setting of headers, cors, and pipelining. This commit begins this moving
in that direction by introducing lower level abstraction (HttpChannel,
HttpRequest, and HttpResonse) that is implemented by the modules. The
higher level rest request and rest channel work can live entirely in
server.
Currently the http pipelining handlers seem to support chunked http
content. However, this does not make sense. There is a content
aggregator in the pipeline before the pipelining handler. This means the
pipelining handler should only see full http messages. Additionally, the
request handler immediately after the pipelining handler only supports
full messages.
This commit modifies both nio and netty4 pipelining handlers to assert
that an inbound message is a full http message. Additionally it removes
the tests for chunked content.
This commit upgrades us to Netty 4.1.25. This upgrade is more
challenging than past upgrades, all because of a new object cleaner
thread that they have added. This thread requires an additional security
permission (set context class loader, needed to avoid leaks in certain
scenarios). Additionally, there is not a clean way to shutdown this
thread which means that the thread can fail thread leak control during
tests. As such, we have to filter this thread from thread leak control.
This is related to #27260 and #28898. This commit adds the transport-nio
plugin as a random option when running the http smoke tests. As part of
this PR, I identified an issue where cors support was not properly
enabled causing these tests to fail when using transport-nio. This
commit also fixes that issue.
This is related to #28898. This commit adds cors support to the nio http
transport. Most of the work is copied directly from the netty module
implementation. Additionally, this commit adds tests for the nio http
channel.
This is related to #31017. That issue identified that these three http
methods were treated like GET requests. This commit adds them to
RestRequest. This means that these methods will be handled properly and
generate 405s.
This commit introduces the ability for a client to communicate to the
server features that it can support and for these features to be used in
influencing the decisions that the server makes when communicating with
the client. To this end we carry the features from the client to the
underlying stream as we carry the version of the client today. This
enables us to enhance the logic where we make protocol decisions on the
basis of the version on the stream to also make protocol decisions on
the basis of the features on the stream. With such functionality, the
client can communicate to the server if it is a transport client, or if
it has, for example, X-Pack installed. This enables us to support
rolling upgrades from the OSS distribution to the default distribution
without breaking client connectivity as we can now elect to serialize
customs in the cluster state depending on whether or not the client
reports to us using the feature capabilities that it can under these
customs. This means that we would avoid sending a client pieces of the
cluster state that it can not understand. However, we want to take care
and always send the full cluster state during node-to-node communication
as otherwise we would end up with different understanding of what is in
the cluster state across nodes depending on which features they reported
to have. This is why when deciding whether or not to write out a custom
we always send the custom if the client is not a transport client and
otherwise do not send the custom if the client is transport client that
does not report to have the feature required by the custom.
Co-authored-by: Yannick Welsch <yannick@welsch.lu>
Currently AbstractHttpServerTransport is in a netty4 module. This is the
incorrect location. This commit moves it out of netty4 module.
Additionally, it moves unit tests that test AbstractHttpServerTransport
logic to server.
Currently nio and netty modules use the CompletableFuture class for
managing listeners. This is unfortunate as that class accepts
Throwable. This commit adds a class CompletableContext that wraps
the CompletableFuture but does not accept Throwable. This allows the
modification of netty and nio logic to no longer handle Throwable.
This commit reintroduces 31251c9 and 63a5799. These commits introduced a
memory leak and were reverted. This commit brings those commits back
and fixes the memory leak by removing unnecessary retain method calls.
This reverts commit 31251c9 introduced in #30695.
We suspect this commit is causing the OOME's reported in #30811 and we will use this PR to test this assertion.
This is related to #29500 and #28898. This commit removes the abilitiy
to disable http pipelining. After this commit, any elasticsearch node
will support pipelined requests from a client. Additionally, it extracts
some of the http pipelining work to the server module. This extracted
work is used to implement pipelining for the nio plugin.
This commit is related to #28898. It adds an nio driven http server
transport. Currently it only supports basic http features. Cors,
pipeling, and read timeouts will need to be added in future PRs.
With this commit we determine the maximum number of buffers that Netty keeps
while accumulating one HTTP request based on the maximum content length (default
1500 bytes, overridable with the system property `es.net.mtu`). Previously, we
kept the default value of 1024 which is too small for bulk requests which leads
to unnecessary copies of byte buffers internally.
Relates #29448