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Motivation: Long-lived HTTP/2 connections (as used by gRPC) lead to an uneven load distribution across server instances: clients stay connected to the instances they found at connect time, and instances added later (after a scale-out or a rolling deploy) receive no share of the existing traffic. The server is the side that can retire a connection gracefully, via GOAWAY. grpc-java offers this as maxConnectionAge; pekko-http has no equivalent (akka/akka-grpc#967 is the corresponding request on the Akka side). Modification: Backport to 1.4.x of the main-branch change adding a `pekko.http.server.http2.max-connection-age` setting, default `infinite` (disabled). When a server connection reaches the configured age, the existing graceful termination path is triggered: GOAWAY(NO_ERROR) is sent, streams that are in flight complete normally, streams opened after the GOAWAY are refused with RST_STREAM(REFUSED_STREAM), and the connection is closed once no streams remain. The age is jittered per connection by a configurable fraction, `max-connection-age-jitter` (default 0.1 = +/- 10%, the value grpc-java applies; 0 disables jitter), so that connections that were opened together are not all closed at the same time. `triggerTermination` now accepts an infinite deadline, in which case no forced-close timer is scheduled. Also corrects the termination debug log, which printed the timer key instead of the deadline. Branch adaptations relative to main: `@since` tags say 1.4.1, the MiMa filter file lives in 1.4.x.backwards.excludes, and getMaxConnectionAge converts the possibly-infinite duration inline because JavaDurationConverter does not exist on this branch. Result: Operators can cap the lifetime of server-side HTTP/2 connections to rebalance long-lived connections across server instances. Behavior is unchanged by default. Tests: - sbt "http2-tests/test": 344 tests pass, including 2 new directional tests for max-connection-age in Http2ServerSpec - PR_TARGET_BRANCH=origin/1.4.x sbt validatePullRequest: all tasks pass except docs/Compile/paradox, which fails identically on a clean checkout of 1.4.x in this environment (pegdown/parboiled parser bootstrap error) - environment issue, not caused by this change - sbt "+http-core/mimaReportBinaryIssues": clean, with 5 new ReversedMissingMethodProblem filters for the added methods - sbt scalafmtCheckAll scalafmtSbtCheck: clean - sbt headerCreateAll: no changes - manual end-to-end check against grpc-java 1.75.0, built from this branch: with max-connection-age = 5s, a client calling every 200 ms for 16 s saw 0 failures across the connection retirements, and a unary call that was in flight when the GOAWAY was sent completed normally References: Refs akka/akka-grpc#967 - equivalent request against akka-http/akka-grpc. 1.4.x companion of the main-branch pull request adding the same setting.
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Kreinoee
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September 24, 2026 18:04
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Motivation
Backport of #1316 to the 1.4.x line, so that the setting is usable before 2.0.0 ships.
See that PR for the full motivation: a
max-connection-agefor HTTP/2 server connections, theserver-side counterpart of grpc-java's
maxConnectionAge(akka/akka-grpc#967 is the correspondingrequest on the Akka side).
Modification
Cherry-pick of the single commit on #1316, with the branch-specific adaptations:
@sincetags say1.4.1(this line) instead of2.0.0(main), following the precedent ofmax-header-list-size (http/2: bound incoming header blocks with max-header-list-size #1247).
1.4.x.backwards.excludes.getMaxConnectionAgeconverts the possibly-infinite Scala duration inline(
ChronoUnit.FOREVER.getDurationfor infinite), becauseJavaDurationConverterdoes not exist onthis branch.
Result
Same as #1316: operators can cap the lifetime of server-side HTTP/2 connections to
rebalance long-lived connections across server instances. Behavior is unchanged by default.
Verified against a real grpc-java (1.75.0) client, same setup as on #1316 but built from
this branch: with
max-connection-age = 5s, a client issuing a unary call every 200 ms for 16 sobserved 0 failures across the connection retirements (the server saw 3 distinct client
connections), and a unary call that was in flight when the GOAWAY was sent completed normally on the
connection being drained.
Tests
sbt "http2-tests/test": pass, including the 2 new directional tests for max-connection-age inHttp2ServerSpecPR_TARGET_BRANCH=origin/1.4.x sbt validatePullRequest: all tasks pass exceptdocs/Compile/paradox,which fails in this environment on a clean checkout of
1.4.xtoo (see the docs/paradox note below)sbt "+http-core/mimaReportBinaryIssues": cleansbt scalafmtCheckAll scalafmtSbtCheck: cleansbt docs/paradox: environment failure unrelated to this change (fails identically on a cleancheckout of
1.4.xwithError creating extended parser class ... org.pegdown.ParserWithDirectives)References
Backport of #1316. Refs akka/akka-grpc#967.