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Message-ID: <cce2ba8c-307e-4244-978e-91174073a4dc@gmail.com>
Date: Sun, 31 May 2026 12:00:01 +0300
MIME-Version: 1.0
User-Agent: Mozilla Thunderbird
Subject: Re: BUG #19494: Error on transaction commit inside pipeline triggers
 psql's Assert
To: Michael Paquier <michael@paquier.xyz>
Cc: pgsql-bugs@lists.postgresql.org
References: <19494-97a86d84fee71c47@postgresql.org>
 <ahe7ylLcESTmnZfk@paquier.xyz> <ahfR7s1ZXC6MSC0i@paquier.xyz>
 <f7cfb56d-c7d6-40d9-b08d-ee5232f95cba@gmail.com>
 <ahkdZJMZvyYlsfXK@paquier.xyz>
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From: Alexander Lakhin <exclusion@gmail.com>
In-Reply-To: <ahkdZJMZvyYlsfXK@paquier.xyz>
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 <https://www.postgresql.org/message-id/cce2ba8c-307e-4244-978e-91174073a4dc%40gmail.com>
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Hello Michael,

29.05.2026 08:00, Michael Paquier wrote:
> When ending the pipeline the loop consuming the results is stuck, so
> we could check the connection state.  We are going to enter in a
> freeze of the branches due to beta1 next week, so let's take our time.
>
> Please feel to use the v2 attached for your tests.  I am also testing
> it more on my side.

Thank you for the fix! I haven't discovered new issues so far.

I've found a way to trigger another assertion, but I don't think it's
legitimate:
--- a/src/backend/libpq/pqcomm.c
+++ b/src/backend/libpq/pqcomm.c
@@ -880,7 +880,7 @@ RemoveSocketFiles(void)
  static void
  socket_set_nonblocking(bool nonblocking)
  {
-       if (MyProcPort == NULL)
+       if ((MyProcPort == NULL) || (rand() % 10 == 0))
                 ereport(ERROR,
(errcode(ERRCODE_CONNECTION_DOES_NOT_EXIST),
                                  errmsg("there is no client connection")));

makes this script:
(
echo "\startpipeline"
for i in {1..50}; do echo "\syncpipeline"; done
echo "
SELECT 1;
\endpipeline

\startpipeline
SELECT 2;
\endpipeline
"
) | psql

trigger
psql: common.c:2055: ExecQueryAndProcessResults: Assertion `pset.piped_syncs > 0' failed.

Probably there could be another way to throw an ERROR on \syncpipeline,
but I have no good idea yet.

Running psql_pipeline in a loop with the above modification applied:
for i in {1..1000}; do echo "ITERATION $i"; NO_TEMP_INSTALL=1 TESTS=psql_pipeline make -s check-tests; done
I also observed the test hanging (at iterations 284. 543, 218) due to loss
of synchronization between psql and postgres.

Best regards,
Alexander
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    <div class="moz-cite-prefix">Hello Michael,<br>
      <br>
      29.05.2026 08:00, Michael Paquier wrote:<br>
    </div>
    <blockquote type="cite" cite="mid:ahkdZJMZvyYlsfXK@paquier.xyz">
      <pre wrap="" class="moz-quote-pre">When ending the pipeline the loop consuming the results is stuck, so
we could check the connection state.  We are going to enter in a
freeze of the branches due to beta1 next week, so let's take our time.

Please feel to use the v2 attached for your tests.  I am also testing
it more on my side.
</pre>
    </blockquote>
    <br>
    Thank you for the fix! I haven't discovered new issues so far.<br>
    <br>
    I've found a way to trigger another assertion, but I don't think
    it's<br>
    legitimate:<br>
    --- a/src/backend/libpq/pqcomm.c<br>
    +++ b/src/backend/libpq/pqcomm.c<br>
    @@ -880,7 +880,7 @@ RemoveSocketFiles(void)<br>
     static void<br>
     socket_set_nonblocking(bool nonblocking)<br>
     {<br>
    -       if (MyProcPort == NULL)<br>
    +       if ((MyProcPort == NULL) || (rand() % 10 == 0))<br>
                    ereport(ERROR,<br>
                                   
    (errcode(ERRCODE_CONNECTION_DOES_NOT_EXIST),<br>
                                     errmsg("there is no client
    connection")));<br>
    <br>
    makes this script:<br>
    (<br>
    echo "\startpipeline"<br>
    for i in {1..50}; do echo "\syncpipeline"; done<br>
    echo "<br>
    SELECT 1;<br>
    \endpipeline<br>
    <br>
    \startpipeline<br>
    SELECT 2;<br>
    \endpipeline<br>
    "<br>
    ) | psql<br>
    <br>
    trigger<br>
    psql: common.c:2055: ExecQueryAndProcessResults: Assertion
    `pset.piped_syncs &gt; 0' failed.<br>
    <br>
    Probably there could be another way to throw an ERROR on
    \syncpipeline,<br>
    but I have no good idea yet. <br>
    <br>
    Running psql_pipeline in a loop with the above modification applied:<br>
    for i in {1..1000}; do echo "ITERATION $i"; NO_TEMP_INSTALL=1
    TESTS=psql_pipeline make -s check-tests; done<br>
    I also observed the test hanging (at iterations 284. 543, 218) due
    to loss<br>
    of synchronization between psql and postgres.<br>
    <br>
    Best regards,<br>
    Alexander<br>
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