HTTP API calls hang with 'Accept-Encoding: zstd'

[reta]

Description

Excluding zstd from the list of default supported compressors: although zstd-jni is on the classpath, ZstdEncoder requires direct buffers supports and which by default NettyAllocator does not provide.

Caused by: java.lang.UnsupportedOperationException: Direct buffers not supported
        at org.opensearch.transport.NettyAllocator$NoDirectBuffers.directBuffer(NettyAllocator.java:289) ~[transport-netty4-client-3.0.0-SNAPSHOT.jar:3.0.0-SNAPSHOT]
        at io.netty.handler.codec.compression.ZstdEncoder.handlerAdded(ZstdEncoder.java:182) ~[netty-codec-4.1.118.Final.jar:4.1.118.Final]
        at io.netty.channel.AbstractChannelHandlerContext.callHandlerAdded(AbstractChannelHandlerContext.java:1130) [netty-transport-4.1.118.Final.jar:4.1.118.Final]
        at io.netty.channel.DefaultChannelPipeline.callHandlerAdded0(DefaultChannelPipeline.java:558) [netty-transport-4.1.118.Final.jar:4.1.118.Final]
        ... 147 more

Related Issues

Closes #17339

Check List

• Functionality includes testing.
• API changes companion pull request created, if applicable.
• Public documentation issue/PR created, if applicable.

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[github-actions]

❌ Gradle check result for 021c389: FAILURE

Please examine the workflow log, locate, and copy-paste the failure(s) below, then iterate to green. Is the failure a flaky test unrelated to your change?

[github-actions]

❌ Gradle check result for 021c389: FAILURE

Please examine the workflow log, locate, and copy-paste the failure(s) below, then iterate to green. Is the failure a flaky test unrelated to your change?

[github-actions]

✅ Gradle check result for 021c389: SUCCESS

[codecov]

Codecov Report

Attention: Patch coverage is 73.33333% with 4 lines in your changes missing coverage. Please review.

Project coverage is 72.48%. Comparing base (abe2333) to head (021c389).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
...nsearch/http/netty4/Netty4HttpServerTransport.java	73.33%	3 Missing and 1 partial ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##               main   #17408      +/-   ##
============================================
+ Coverage     72.41%   72.48%   +0.07%     
- Complexity    65667    65672       +5     
============================================
  Files          5303     5303              
  Lines        304781   304793      +12     
  Branches      44201    44202       +1     
============================================
+ Hits         220709   220932     +223     
+ Misses        65959    65770     -189     
+ Partials      18113    18091      -22     

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[andrross]

I agree this is the right fix, but should we create an issue to add direct buffer support to NettyAllocator and add an option to use zstd compression here?

[reta]

I agree this is the right fix, but should we create an issue to add direct buffer support to NettyAllocator and add an option to use zstd compression here?

Thanks @andrross , I will open up an issue to research why Netty transport uses NoDirectBuffers allocator - it was certainly the deliberate decision. Thank you.

UPD: #17413

[opensearch-trigger-bot]

The backport to 2.x failed:

The process '/usr/bin/git' failed with exit code 128

To backport manually, run these commands in your terminal:

# Navigate to the root of your repository
cd $(git rev-parse --show-toplevel)
# Fetch latest updates from GitHub
git fetch
# Create a new working tree
git worktree add ../.worktrees/OpenSearch/backport-2.x 2.x
# Navigate to the new working tree
pushd ../.worktrees/OpenSearch/backport-2.x
# Create a new branch
git switch --create backport/backport-17408-to-2.x
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick -x --mainline 1 ca8e4f871a1cfec70985aa6acea33f0c36484be5
# Push it to GitHub
git push --set-upstream origin backport/backport-17408-to-2.x
# Go back to the original working tree
popd
# Delete the working tree
git worktree remove ../.worktrees/OpenSearch/backport-2.x

Then, create a pull request where the base branch is 2.x and the compare/head branch is backport/backport-17408-to-2.x.