Re: Perform streaming logical transactions by background workers and parallel apply
Amit Kapila <amit.kapila16@gmail.com>
On Wed, Dec 7, 2022 at 8:28 AM houzj.fnst@fujitsu.com
<houzj.fnst@fujitsu.com> wrote:
>
> Besides, I fixed a bug where there could still be messages left in memory
> queue and the PA has started to apply spooled message.
>
Few comments on the recent changes in the patch:
========================================
1. It seems you need to set FS_SERIALIZE_DONE in
stream_prepare/commit/abort. They are still directly setting the state
as READY. Am, I missing something or you forgot to change it?
2.
case TRANS_PARALLEL_APPLY:
pa_stream_abort(&abort_data);
+ /*
+ * Reset the stream_fd after aborting the toplevel transaction in
+ * case the parallel apply worker is applying spooled messages
+ */
+ if (toplevel_xact)
+ stream_fd = NULL;
I think we can keep the handling of stream file the same in
abort/commit/prepare code path.
3. It is already pointed out by Peter that it is better to add some
comments in pa_spooled_messages() function that we won't be
immediately able to apply changes after the lock is released, it will
be done in the next cycle.
4. Shall we rename FS_SERIALIZE as FS_SERIALIZE_IN_PROGRESS? That will
appear consistent with FS_SERIALIZE_DONE.
5. Comment improvements:
diff --git a/src/backend/replication/logical/worker.c
b/src/backend/replication/logical/worker.c
index b26d587ae4..921d973863 100644
--- a/src/backend/replication/logical/worker.c
+++ b/src/backend/replication/logical/worker.c
@@ -1934,8 +1934,7 @@ apply_handle_stream_abort(StringInfo s)
}
/*
- * Check if the passed fileno and offset are the last fileno and position of
- * the fileset, and report an ERROR if not.
+ * Ensure that the passed location is fileset's end.
*/
static void
ensure_last_message(FileSet *stream_fileset, TransactionId xid, int fileno,
@@ -2084,9 +2083,9 @@ apply_spooled_messages(FileSet *stream_fileset,
TransactionId xid,
nchanges++;
/*
- * Break the loop if stream_fd is set to NULL which
means the parallel
- * apply worker has finished applying the transaction.
The parallel
- * apply worker should have closed the file before committing.
+ * It is possible the file has been closed because we
have processed
+ * some transaction end message like stream_commit in
which case that
+ * must be the last message.
*/
--
With Regards,
Amit Kapila.
Commits
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the thread's linked commits as JSON, with link sources.
API reference →
-
Fix invalid memory access during the shutdown of the parallel apply worker.
- 3d144c6c8602 16.0 landed
-
Fix assertion failure in apply worker.
- de63f8dadee4 16.0 landed
-
Use elog to report unexpected action in handle_streamed_transaction().
- 781ac42d43ab 16.0 landed
-
Use appropriate wait event when sending data in the apply worker.
- d9d7fe68d35e 16.0 landed
-
Allow the logical_replication_mode to be used on the subscriber.
- 9f2213a7c575 16.0 landed
-
Rename GUC logical_decoding_mode to logical_replication_mode.
- 1e8b61735cfb 16.0 landed
-
Display the leader apply worker's PID for parallel apply workers.
- d540a02a724b 16.0 landed
-
Improve the code to decide and process the apply action.
- c981d9145dea 16.0 landed
-
Document the newly added wait events added by commit 216a784829.
- cd06ccd78fcf 16.0 landed
-
Perform apply of large transactions by parallel workers.
- 216a784829c2 16.0 landed
-
Wake up a subscription's replication worker processes after DDL.
- c6e1f62e2cee 16.0 cited
-
Add copyright notices to meson files
- 8284cf5f746f 16.0 cited
-
Better document logical replication parameters
- a8500750ca0a 16.0 cited
-
Add a common function to generate the origin name.
- 776e1c8a5d14 16.0 cited
-
Harmonize parameter names in storage and AM code.
- bfcf1b34805f 16.0 cited
-
Avoid using list_length() to test for empty list.
- efd0c16becbf 16.0 cited
-
Improve two comments related to a boolean DefElem's value
- 8445f5a21d40 16.0 cited
-
Fix partition table's REPLICA IDENTITY checking on the subscriber.
- 26b3455afaa9 15.0 cited
-
Fix data inconsistency between publisher and subscriber.
- b7658c24c7c1 15.0 cited
-
Fix cache look-up failures while applying changes in logical replication.
- 5a97b1325453 15.0 cited