http2: invoke pending write callback on stream destroy

[mcollina]

Summary

• Track the pending write callback on Http2Stream via kPendingWriteCb and invoke it in _destroy() before calling handle.destroy(), ensuring the Writable stream can clean up properly when a stream is destroyed mid-write
• Make the write callback idempotent so duplicate invocations from the C++ side are harmless no-ops

When an HTTP/2 stream is destroyed while a write is in progress, the pending write callback may never be called if the write data has already been consumed by nghttp2 and moved to the session's outgoing_buffers_. This leaves the Writable stream's kWriting flag set permanently, preventing errorBuffer from cleaning up remaining buffered writes and keeping references alive that block event loop exit.

Fixes: #58252
Refs: #58253

Test plan

• test-http2-close-while-writing passes consistently
• Stress tested with 500 repetitions — zero failures
• Full HTTP/2 test suite (test-http2-*) passes with no regressions

[nodejs-github-bot]

Review requested:

• @nodejs/http2
• @nodejs/net

[lpinca]

Is it possible to add a dedicated test? This allows up to clean up test-http2-close-while-writing.

[lpinca]

It does not fix the issue:

$ python3 tools/test.py --repeat=10000 parallel/test-http2-close-while-writing
=== release test-http2-close-while-writing ===                    
Path: parallel/test-http2-close-while-writing
Command: out/Release/node /Users/luigi/code/node/test/parallel/test-http2-close-while-writing.js
--- TIMEOUT ---


=== release test-http2-close-while-writing ===                    
Path: parallel/test-http2-close-while-writing
Command: out/Release/node /Users/luigi/code/node/test/parallel/test-http2-close-while-writing.js
--- TIMEOUT ---


=== release test-http2-close-while-writing ===                    
Path: parallel/test-http2-close-while-writing
Command: out/Release/node /Users/luigi/code/node/test/parallel/test-http2-close-while-writing.js
--- TIMEOUT ---


=== release test-http2-close-while-writing ===                    
Path: parallel/test-http2-close-while-writing
Command: out/Release/node /Users/luigi/code/node/test/parallel/test-http2-close-while-writing.js
--- TIMEOUT ---


=== release test-http2-close-while-writing ===                    
Path: parallel/test-http2-close-while-writing
Command: out/Release/node /Users/luigi/code/node/test/parallel/test-http2-close-while-writing.js
--- TIMEOUT ---


[05:03|% 100|+ 9995|-   5]: Done                                  

Failed tests:
out/Release/node /Users/luigi/code/node/test/parallel/test-http2-close-while-writing.js
out/Release/node /Users/luigi/code/node/test/parallel/test-http2-close-while-writing.js
out/Release/node /Users/luigi/code/node/test/parallel/test-http2-close-while-writing.js
out/Release/node /Users/luigi/code/node/test/parallel/test-http2-close-while-writing.js
out/Release/node /Users/luigi/code/node/test/parallel/test-http2-close-while-writing.js

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 89.72%. Comparing base (ae2ffce) to head (c16f526).
⚠️ Report is 75 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #61821      +/-   ##
==========================================
- Coverage   89.75%   89.72%   -0.03%     
==========================================
  Files         674      675       +1     
  Lines      204416   204807     +391     
  Branches    39285    39351      +66     
==========================================
+ Hits       183472   183766     +294     
- Misses      13227    13331     +104     
+ Partials     7717     7710       -7     

Files with missing lines	Coverage Δ
lib/internal/http2/core.js	95.20% <100.00%> (-0.03%)	⬇️

... and 73 files with indirect coverage changes

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