stream: resume flow when an errored pipe destination is removed#64310
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When a source is piped to multiple destinations and one destination errors synchronously in `_write()`, `write()` returns false without setting `needDrain` (since the "avoid unnecessary drain for sync stream" change). The pipe cleanup only re-invoked the source's drain handler when the destination still had `needDrain` set, so the errored destination was never removed from the source's `awaitDrainWriters` set. The source stayed paused forever and any remaining healthy destination stopped receiving data. Always invoke the drain handler during cleanup. `pipeOnDrain` only removes this destination from the awaiting-drain set and resumes the source once nothing else is awaiting a drain, so it is safe to call unconditionally and no-ops when this destination was not awaiting a drain. Fixes: nodejs#53185 Signed-off-by: Mahin Anowar <86069420+MahinAnowar@users.noreply.github.com>
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Fixes: #53185
Problem
When a source is piped to two destinations and one destination errors synchronously in
_write(), the source stops flowing to the healthy destination as well. This is a regression from v20.10.0 (bisected to #50014 in the issue), where the healthy destination received all the data.Cause
After #50014 ("avoid unnecessary drain for sync stream"), a synchronous
write()to a destination that errors returnsfalsewithout settingneedDrain. On the readable side,pause()adds that destination tostate.awaitDrainWritersand pauses the source. When the errored destination unpipes,cleanup()only re-invokes the source's drain handler whendest._writableState.needDrainis set — which is now false for the sync-errored destination. So the dead destination is never removed fromawaitDrainWriters,pipeOnDrainnever sees an empty set, and the source stays paused, starving the healthy destination.Fix
Call the drain handler unconditionally in
cleanup().pipeOnDrainonly removes the given destination fromawaitDrainWritersand resumes the source once nothing else is awaiting a drain, so calling it is safe and no-ops when the destination wasn't awaiting a drain. This restores the pre-20.10 behavior (matching the direction @mcollina noted on the issue).Test
test/parallel/test-stream-pipe-multiple-destinations-error.jspipes a source to a synchronously-erroring destination and a healthy counting destination, writes two over-highWaterMark chunks, and asserts the healthy destination receives everything. It fails on currentmain(the source stalls and the healthy destination only gets the first chunk) and passes with this change.