core: Avoid spawning waiter goroutines when QUIC worker pool is full#7927
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When streamProcessPool is full, serveQUICConnection() currently spawns a goroutine that waits for a worker token. Under load this can create a large backlog of goroutines waiting on the pool. This change removes the waiter goroutine and instead blocks in the connection loop until a worker slot becomes available or the connection context is canceled. Signed-off-by: Yong Tang <yong.tang.github@outlook.com>
thevilledev
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Mar 16, 2026
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Nice! The blocking approach here aligns well with the other server implementations do it. Both HTTPS and gRPC block their accept loops via netutil.LimitListener rather than spawning waiters (see GHSA-527x-5wrf-22m2). The current QUIC code was the outlier in that regard.
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1. Why is this pull request needed and what does it do?
When streamProcessPool is full, serveQUICConnection() currently spawns a goroutine that waits for a worker token. Under load this can create a large backlog of goroutines waiting on the pool.
This change removes the waiter goroutine and instead blocks in the connection loop until a worker slot becomes available or the connection context is canceled.
2. Which issues (if any) are related?
n/a
3. Which documentation changes (if any) need to be made?
n/a
4. Does this introduce a backward incompatible change or deprecation?
n/a