Provide a way to terminate unfinished requests after graceful shutdown #5941
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Motivation:
Unfinished requests even after graceful shutdown period are forcivily
closed with `ClosedSessionException`. As `ClosedSessionException`
indicates that the connection was unexpectedly disconnected,
`ClosedSessionException` is not suitable for graceful shutdown.
In this PR, I propose to add `ShuttingDownException` to terminate
unfinished requests when a server stops.
Modifications:
- Introduce `GracefulShutdown` to customize graceful shutdown behavior.
- Users can specify a error function to create an exception to
unfinished terminate requests.
- Fixed `HttpServerHandler` to send error responses using the error
function of `GracefulShutdown`
- Fixed `Server` to send error respones first and then close the
connnections.
- Deprecation) `ServerConfig.gracefulShutdownQuietPeriod()` and
`ServerConfig.gracefulShutdownTimeout()` have been deprecated in favor
of `ServerConfig.gracefulShutdown()`.
Result:
You can now use `GracefulShutdown` to terminate unfinished requests when
a server stops.
```java
GracefulShutdown gracefulShutdown =
GracefulShutdown
.builder()
.quietPeriod(Duration.ofSeconds(10))
.timeout(Duration.ofSeconds(15))
.shutdownErrorFunction((ctx, req) -> {
return new ServerStopException();
})
.build();
Server
.builder()
.gracefulShutdown(gracefulShutdown);
```
| /** | ||
| * Returns the quiet period to wait for active requests to go end before shutting down. | ||
| * {@link Duration#ZERO} means the server will stop right away without waiting. | ||
| */ | ||
| Duration quietPeriod(); | ||
|
|
||
| /** | ||
| * Returns the amount of time to wait before shutting down the server regardless of active requests. | ||
| * This should be set to a time greater than {@code quietPeriod} to ensure the server shuts down even | ||
| * if there is a stuck request. | ||
| */ | ||
| Duration timeout(); |
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Should we make this even more flexible rather than just letting a user configure the quiet period and timeout? For example:
interface GracefulShutdown {
...
// Armeria core passes its GracefulShutdownHandler to this method.
void startGracefulShutdown(GracefulShutdownHandler handler);
}
// A GracefulShutdown implementation calls back Armeria core via this handler.
interface GracefulShutdownHandler {
void gracefulShutdownStarted(...);
void quietPeriodComplete(...);
void gracefulShutdownComplete(...);
@Nullable
Throwable toException(ctx, req);
}
| for (Channel ch : children) { | ||
| final HttpServerHandler serverHandler = ch.pipeline().get(HttpServerHandler.class); | ||
| if (serverHandler != null) { | ||
| closeFutures.add(serverHandler.shutdown(ch)); |
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This is called from the startStopExecutor, which breaks the assumption that HttpServerHandler#cleanup is called from the event loop assigned to the channel.
Is this intentional?
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Nice catch, it was my mistake.
| if (bossGroups.isEmpty()) { | ||
| finishDoStop(future); | ||
| return; | ||
| shutdownServerHandlers().handle((unused3, unused4) -> { |
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I understood now, that requests are closed with an exception once before closing the socket directly.
As a result, users will see more 503 responses instead of connection resets
| .map(DecodedHttpRequest::whenResponseSent) | ||
| .toArray(CompletableFuture[]::new); | ||
| CompletableFuture.allOf(futures).handle((unused0, unused1) -> { | ||
| completionFuture.complete(null); |
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Note: checked that the order of completing the future vs. close the encoder doesn't really matter as 1) pipeline requests are aborted above 2) the timing of closing the keepAliveHandler doesn't really matter
|
Changed the target milestone to 1.32.0. I need some time to figure out how to implement the API that Trustin suggested. |
Motivation:
Unfinished requests even after graceful shutdown period are forcibly closed with
ClosedSessionException. AsClosedSessionExceptionindicates that the connection was unexpectedly disconnected,ClosedSessionExceptionis not suitable for graceful shutdown.In this PR, I propose to add
ShuttingDownExceptionto terminate unfinished requests when a server stops.Modifications:
GracefulShutdownto customize graceful shutdown behavior.HttpServerHandlerto send error responses using the error function ofGracefulShutdownServerto send error respones first and then close the connnections.ServerConfig.gracefulShutdownQuietPeriod()andServerConfig.gracefulShutdownTimeout()have been deprecated in favor ofServerConfig.gracefulShutdown().Result:
You can now use
GracefulShutdownto terminate unfinished requests when a server stops.