patricklucas commented on code in PR #22987:
URL: https://github.com/apache/flink/pull/22987#discussion_r1263527019
##########
flink-runtime/src/main/java/org/apache/flink/runtime/rest/RestClient.java:
##########
@@ -501,6 +501,22 @@ private <P extends ResponseBody> CompletableFuture<P>
submitRequest(
}
});
+ // [FLINK-32583] If connectFuture failed instantly but channelFuture
is unresolved, it may
+ // mean the executor service Netty is using has shut down, in which
case the above listener
+ // to complete channelFuture will never run
+ if (connectFuture.isDone() && !connectFuture.isSuccess() &&
!channelFuture.isDone()) {
Review Comment:
While trying to get a better picture of the various cases we might need to
handle to get full coverage here I took a step back and tried to get a broader
view of this.
I verified that the event loop/executor for both the connection as well as
its listeners is the same, the NioEventLoopGroup `bootstrap` is configured with
elsewhere in RestClient, and I saw that when the client is shut down, this
group is asked to shut down gracefully with a "quiet period" of 0 and a default
timeout of 10 seconds. As far as I can tell, already-scheduled tasks are
allowed to run to completion.
I believe we could cover the vast majority of cases by simply checking
`isRunning` at the top of `submitRequest`—if the client has already been closed
and graceful shutdown of the group initiated, we should immediately reject any
new requests.
The challenge in particular is covering the case where the client is shut
down after the call to `bootstrap.connect()` but before the listeners are
notified. Depending on configured timeouts, the connect task may run to
completion or time out, but not be able to notify its listeners and thus
resolve `channelFuture`. I don't think we have any way to detect this within
`submitRequest` itself.
The only solution that comes to mind here would be to:
- Add each `channelFuture` created in `submitRequest` to a class-level
collection
- In the listener attached to `connectFuture`, remove the `channelFuture`
from that collection after calling `complete`/`completeExceptionally`
- In the listener in `shutdownInternally` that is notified when the event
loop shuts down, resolve all remaining futures in the collection exceptionally
Having written it down it doesn't sound as complex as I first thought, but
it's still clearly beyond what I had originally hoped for this change.
@XComp Thoughts? Should I go with simply checking whether the client has
already been closed at the top of `submitRequest`, implement this "future
cleanup" logic, or both?
##########
flink-runtime/src/main/java/org/apache/flink/runtime/rest/RestClient.java:
##########
@@ -501,6 +501,22 @@ private <P extends ResponseBody> CompletableFuture<P>
submitRequest(
}
});
+ // [FLINK-32583] If connectFuture failed instantly but channelFuture
is unresolved, it may
+ // mean the executor service Netty is using has shut down, in which
case the above listener
+ // to complete channelFuture will never run
+ if (connectFuture.isDone() && !connectFuture.isSuccess() &&
!channelFuture.isDone()) {
Review Comment:
While trying to get a better picture of the various cases we might need to
handle to get full coverage here I took a step back and tried to get a broader
view of this.
I verified that the event loop/executor for both the connection as well as
its listeners is the same, the NioEventLoopGroup `bootstrap` is configured with
elsewhere in RestClient, and I saw that when the client is shut down, this
group is asked to shut down gracefully with a "quiet period" of 0 and a default
timeout of 10 seconds. As far as I can tell, already-scheduled tasks are
allowed to run to completion.
I believe we could cover the vast majority of cases by simply checking
`isRunning` at the top of `submitRequest`—if the client has already been closed
and graceful shutdown of the group initiated, we should immediately reject any
new requests.
The challenge in particular is covering the case where the client is shut
down after the call to `bootstrap.connect()` but before the listeners are
notified. Depending on configured timeouts, the connect task may run to
completion or time out, but not be able to notify its listeners and thus
resolve `channelFuture`. I don't think we have any way to detect this within
`submitRequest` itself.
The only solution that comes to mind here would be to:
- Add each `channelFuture` created in `submitRequest` to a class-level
collection
- In the listener attached to `connectFuture`, remove the `channelFuture`
from that collection after calling `complete`/`completeExceptionally`
- In the listener in `shutdownInternally` that is notified when the event
loop shuts down, resolve all remaining futures in the collection exceptionally
Having written it down it doesn't sound as complex as I first thought, but
it's still clearly beyond what I had originally hoped for this change.
@XComp Thoughts? Should I go with simply checking whether the client has
already been closed at the top of `submitRequest`, implement this "future
cleanup" logic, or both?
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