Fix NOTIFY wakeups for pre-commit LISTEN entries. Commit 282b1cde9 made SignalBackends() ignore ListenerEntry entries whose "listening" flag said that the listener was not yet committed. That will be true for a new listener that has already registered its queue position, but has not yet reached AtCommit_Notify(). If another backend notifies the same channel in that window, SignalBackends() would directly advance the new listener's queue position, causing it to miss message(s). Really this is a definitional question: is a new listener active as of PreCommit, or as of AtCommit? But it seems to make more sense to expect that the new listener will see all messages after its initially-registered queue position, especially since the direct-advance logic is supposed to be an optimization that doesn't affect semantics.
Fix this by treating all channel entries as valid wakeup targets. Rename the "listening" flag to removeOnAbort to reflect its remaining purpose: identifying staged LISTEN entries that abort cleanup must remove. While we're here, remove an obsolete test case added by 282b1cde9. The check for "ChannelHashAddListener array growth" was meant to exercise code that never made it into the committed patch, so now it's just a waste of test cycles. Author: Joel Jacobson <[email protected]> Reviewed-by: Arseniy Mukhin <[email protected]> Reviewed-by: Tom Lane <[email protected]> Discussion: https://postgr.es/m/[email protected] Discussion: https://postgr.es/m/[email protected] Branch ------ master Details ------- https://git.postgresql.org/pg/commitdiff/0f24332aeb4f43409c2a7bec9fef1e3317689bc5 Modified Files -------------- src/backend/commands/async.c | 62 ++++++++++++++-------------- src/test/isolation/expected/async-notify.out | 11 +---- src/test/isolation/specs/async-notify.spec | 9 ---- 3 files changed, 33 insertions(+), 49 deletions(-)
