Github user NicoK commented on a diff in the pull request: https://github.com/apache/flink/pull/4533#discussion_r153446896 --- Diff: flink-runtime/src/main/java/org/apache/flink/runtime/io/network/netty/CreditBasedClientHandler.java --- @@ -102,13 +102,21 @@ void cancelRequestFor(InputChannelID inputChannelId) { } } + /** + * The credit is announced based on sender's backlog from buffer response, so the channel is + * already active then. If the channel is closed because of error, we can skip this announcement. + * + * @param inputChannel The input channel with unannounced credits. + */ void notifyCreditAvailable(final RemoteInputChannel inputChannel) { - ctx.executor().execute(new Runnable() { - @Override - public void run() { - ctx.pipeline().fireUserEventTriggered(inputChannel); - } - }); + if (ctx != null) { --- End diff -- I actually preferred the previous implementation because it would throw in case of invalid use, i.e. if the channel had not been active before. Or is there a use case for `ctx == null` that is valid and where we really should skip credit notification? But recall since we are only ever calling this when the credit moves from 0 to 1 and therefore, if we ever skip one notification, we will not be notified again!
---