[MIbtehajNasar]

This relates to...

Fixes #6054

Rationale

When DispatcherBase.dispatch() rejects a request, for example because of an invalid header value, it returns false. Pool reads false as backpressure and marks the client as needing drain. The request was never queued, so the client never emits 'drain'. With connections: 1, every later request waits in the pool queue.

Changes

Features

N/A

Bug Fixes

• After a rejected request, dispatch() returns false only when the dispatcher is closed or destroyed, because those never drain. A rejected request doesn't make the dispatcher busy, so in all other cases it returns true. This matches the documented meaning of false: busy until 'drain'.
• PoolBase is the only reader of the return value in lib/: dispatch(), the drain handler and the resume loop. All three get the fix.
• Added a test to test/pool.js: after a request with an invalid header, a pool with connections: 1 still sends the next request. On main the second request stays queued.

Breaking Changes and Deprecations

N/A

Status

• I have read and agreed to the Developer's Certificate of Origin
• Tested
• Benchmarked (optional)
• Documented
• Review ready
• In review
• Merge ready

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 91.57%. Comparing base (f4e4e45) to head (b53221c).
⚠️ Report is 4 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #6055   +/-   ##
=======================================
  Coverage   91.57%   91.57%           
=======================================
  Files         113      113           
  Lines       43938    43940    +2     
=======================================
+ Hits        40235    40239    +4     
+ Misses       3703     3701    -2     

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