Hard-enforce max_active_streams_in at HTTP/2 stream creation#13388
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proxy.config.http2.max_active_streams_in previously only adjusted the advertised SETTINGS_MAX_CONCURRENT_STREAMS, leaving the proxy unable to bound buffered response memory against clients that open streams faster than the advisory throttle reacts. It now also carries a finite default so the cap is no longer effectively unlimited. The new knob proxy.config.http2.max_active_streams_policy_in selects enforcement. Value 0 keeps the advisory behavior that lowers advertised concurrency to min_concurrent_streams_in. Value 1 refuses new inbound streams with REFUSED_STREAM once the process-wide active-stream count reaches the limit and leaves the advertised value untouched. Refusal happens after HPACK decoding so the dynamic table stays in sync and the connection survives; max_active_streams_exceeded_in counts each refusal. max_active_streams_in now defaults to 200000 rather than 0. (cherry picked from commit c76a7c81220fca009ff4dc7de91647c3cf6d72d7)
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ezelkow1
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Jul 15, 2026
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proxy.config.http2.max_active_streams_in previously only adjusted the advertised SETTINGS_MAX_CONCURRENT_STREAMS, leaving the proxy unable to bound buffered response memory against clients that open streams faster than the advisory throttle reacts. It now also carries a finite default so the cap is no longer effectively unlimited.
The new knob proxy.config.http2.max_active_streams_policy_in selects enforcement. Value 0 keeps the advisory behavior that lowers advertised concurrency to min_concurrent_streams_in. Value 1 refuses new inbound streams with REFUSED_STREAM once the process-wide active-stream count reaches the limit and leaves the advertised value untouched. Refusal happens after HPACK decoding so the dynamic table stays in sync and the connection survives; max_active_streams_exceeded_in counts each refusal.
max_active_streams_in now defaults to 200000 rather than 0.
(cherry picked from commit c76a7c81220fca009ff4dc7de91647c3cf6d72d7)