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Message-ID: <90bd2cbb-49ce-4092-9f61-5ac2ab782c94@gmail.com>
Date: Sat, 24 Jan 2026 21:00:00 +0200
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User-Agent: Mozilla Thunderbird
Subject: Re: Buffer locking is special (hints, checksums, AIO writes)
To: Tom Lane <tgl@sss.pgh.pa.us>, Andres Freund <andres@anarazel.de>
Cc: Chao Li <li.evan.chao@gmail.com>, Kirill Reshke <reshkekirill@gmail.com>,
 Heikki Linnakangas <hlinnaka@iki.fi>,
 Melanie Plageman <melanieplageman@gmail.com>,
 Matthias van de Meent <boekewurm+postgres@gmail.com>,
 pgsql-hackers@postgresql.org, Thomas Munro <thomas.munro@gmail.com>,
 Noah Misch <noah@leadboat.com>, Robert Haas <robertmhaas@gmail.com>,
 Michael Paquier <michael.paquier@gmail.com>
References: <4csodkvvfbfloxxjlkgsnl2lgfv2mtzdl7phqzd4jxjadxm4o5@usw7feyb5bzf>
 <CALdSSPgyc7VuMLUZ8J7v2G-PebBa_vEi+mp-cLkcOwNycB56Hw@mail.gmail.com>
 <kjdgvws34gpnz4y6xu5aaeul5mspgy3ahvyiw4lndb3ecsacdb@b2ccyowotpqh>
 <jtg5cu4n6h5lib3kzx66ju4yhh6kmviaud7oq6dtut6c4q4rdi@xwsfoagt3c2b>
 <9C2494E1-F446-42DF-B070-7E231B8E6221@gmail.com>
 <vrnib3bf726ht72jlccu252qm65lzexutydtagytstsjszpiya@ece6xi7o4nfx>
 <F6A52B41-2FFA-4592-BD9B-0438F610B6A2@gmail.com>
 <cj5mcjdpucvw4a54hehslr3ctukavrbnxltvuzzhqnimvpju5e@cy3g3mnsefwz>
 <58821140-0182-4FF3-9A4F-5B168DDB9243@gmail.com>
 <732580B4-962F-4EBD-8811-F4667D79747D@gmail.com>
 <wat7azo4hpgux7ptvozfedtw6hnz7pih3vvnfipxdlcci6fuf3@wacut36qcac7>
 <934395.1768518154@sss.pgh.pa.us>
Content-Language: en-US
From: Alexander Lakhin <exclusion@gmail.com>
In-Reply-To: <934395.1768518154@sss.pgh.pa.us>
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Hello Andres,

16.01.2026 01:02, Tom Lane wrote:
> Various buildfarm animals are complaining about fcb9c977a,
> similarly to this from calliphoridae [1]:

I've discovered another anomaly introduced with fcb9c977a, this time
run-time:
for i in `seq 300`; do
echo "iteration $i"

echo "
create table t(f1 text);
create index on t using spgist(f1);
insert into t select 'a' from generate_series(1, 9000) g(i);
vacuum analyze t;
insert into t select 'b' from generate_series(1, 1000) g(i);
drop table t;
" | psql >/dev/null -v ON_ERROR_STOP=1 || break;
done

fails for me as below:
...
iteration 39
server closed the connection unexpectedly

Core was generated by `postgres: law regression [local] INSERT                 '.
Program terminated with signal SIGABRT, Aborted.
#0  __pthread_kill_implementation (no_tid=0, signo=6, threadid=<optimized out>) at ./nptl/pthread_kill.c:44

warning: 44     ./nptl/pthread_kill.c: Нет такого файла или каталога
(gdb) bt
#0  __pthread_kill_implementation (no_tid=0, signo=6, threadid=<optimized out>) at ./nptl/pthread_kill.c:44
#1  __pthread_kill_internal (signo=6, threadid=<optimized out>) at ./nptl/pthread_kill.c:78
#2  __GI___pthread_kill (threadid=<optimized out>, signo=signo@entry=6) at ./nptl/pthread_kill.c:89
#3  0x000073625aa4527e in __GI_raise (sig=sig@entry=6) at ../sysdeps/posix/raise.c:26
#4  0x000073625aa288ff in __GI_abort () at ./stdlib/abort.c:79
#5  0x00005a479e2f685f in ExceptionalCondition (conditionName=conditionName@entry=0x5a479e403cb8 "entry->data.lockmode 
== BUFFER_LOCK_UNLOCK", fileName=fileName@entry=0x5a479e37a84f "bufmgr.c", lineNumber=lineNumber@entry=5908) at assert.c:65
#6  0x00005a479e14d87c in BufferLockConditional (buffer=<optimized out>, buf_hdr=0x73624e882b40, 
mode=mode@entry=BUFFER_LOCK_EXCLUSIVE) at bufmgr.c:5908
#7  0x00005a479e14f4d5 in ConditionalLockBuffer (buffer=buffer@entry=13500) at bufmgr.c:6474
#8  0x00005a479de44da9 in SpGistNewBuffer (index=index@entry=0x73625b1f6ce8) at spgutils.c:420
#9  0x00005a479de45397 in allocNewBuffer (index=index@entry=0x73625b1f6ce8, flags=flags@entry=3) at spgutils.c:528
#10 0x00005a479de456a0 in SpGistGetBuffer (index=index@entry=0x73625b1f6ce8, flags=flags@entry=3, needSpace=<optimized 
out>, needSpace@entry=4088, isNew=isNew@entry=0x7ffd8fa1b2a7) at spgutils.c:663
#11 0x00005a479de3c913 in doPickSplit (index=index@entry=0x73625b1f6ce8, state=state@entry=0x7ffd8fa1b740, 
current=current@entry=0x7ffd8fa1b510, parent=parent@entry=0x7ffd8fa1b530, 
newLeafTuple=newLeafTuple@entry=0x5a47cbd7adc8, level=level@entry=4, isNulls=false, isNew=false) at spgdoinsert.c:1046
#12 0x00005a479de3e542 in spgdoinsert (index=index@entry=0x73625b1f6ce8, state=state@entry=0x7ffd8fa1b740, 
heapPtr=heapPtr@entry=0x5a47cbe0b248, datums=datums@entry=0x7ffd8fa1b8d0, isnulls=isnulls@entry=0x7ffd8fa1b8b0) at 
spgdoinsert.c:2134
#13 0x00005a479de40137 in spginsert (index=0x73625b1f6ce8, values=0x7ffd8fa1b8d0, isnull=0x7ffd8fa1b8b0, 
ht_ctid=0x5a47cbe0b248, heapRel=<optimized out>, checkUnique=<optimized out>, indexUnchanged=false, 
indexInfo=0x5a47cbe0b0b8) at spginsert.c:206
#14 0x00005a479df981d8 in ExecInsertIndexTuples (resultRelInfo=resultRelInfo@entry=0x5a47cbe07120, 
slot=slot@entry=0x5a47cbe0b218, estate=estate@entry=0x5a47cbe06c10, update=update@entry=false, 
noDupErr=noDupErr@entry=false, specConflict=specConflict@entry=0x0, arbiterIndexes=0x0, onlySummarizing=false) at 
execIndexing.c:449
#15 0x00005a479dfcc6a9 in ExecInsert (context=context@entry=0x7ffd8fa1bb70, 
resultRelInfo=resultRelInfo@entry=0x5a47cbe07120, slot=slot@entry=0x5a47cbe0b218, canSetTag=<optimized out>, 
inserted_tuple=inserted_tuple@entry=0x0, insert_destrel=insert_destrel@entry=0x0) at nodeModifyTable.c:1240
#16 0x00005a479dfcdf67 in ExecModifyTable (pstate=0x5a47cbe06f10) at nodeModifyTable.c:4485
...

Best regards,
Alexander
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    <div class="moz-cite-prefix">Hello Andres,<br>
      <br>
      16.01.2026 01:02, Tom Lane wrote:<br>
    </div>
    <blockquote type="cite" cite="mid:934395.1768518154@sss.pgh.pa.us">
      <pre wrap="" class="moz-quote-pre">Various buildfarm animals are complaining about fcb9c977a,
similarly to this from calliphoridae [1]:
</pre>
    </blockquote>
    <br>
    I've discovered another anomaly introduced with fcb9c977a, this time<br>
    run-time:<br>
    for i in `seq 300`; do<br>
    echo "iteration $i"<br>
    <br>
    echo "<br>
    create table t(f1 text);<br>
    create index on t using spgist(f1);<br>
    insert into t select 'a' from generate_series(1, 9000) g(i);<br>
    vacuum analyze t;<br>
    insert into t select 'b' from generate_series(1, 1000) g(i);<br>
    drop table t;<br>
    " | psql &gt;/dev/null -v ON_ERROR_STOP=1 || break;<br>
    done<br>
    <br>
    fails for me as below:<br>
    ...<br>
    iteration 39<br>
    server closed the connection unexpectedly<br>
    <br>
    Core was generated by `postgres: law regression [local]
    INSERT                 '.<br>
    Program terminated with signal SIGABRT, Aborted.<br>
    #0  __pthread_kill_implementation (no_tid=0, signo=6,
    threadid=&lt;optimized out&gt;) at ./nptl/pthread_kill.c:44<br>
    <br>
    warning: 44     ./nptl/pthread_kill.c: Нет такого файла или каталога<br>
    (gdb) bt<br>
    #0  __pthread_kill_implementation (no_tid=0, signo=6,
    threadid=&lt;optimized out&gt;) at ./nptl/pthread_kill.c:44<br>
    #1  __pthread_kill_internal (signo=6, threadid=&lt;optimized
    out&gt;) at ./nptl/pthread_kill.c:78<br>
    #2  __GI___pthread_kill (threadid=&lt;optimized out&gt;,
    signo=signo@entry=6) at ./nptl/pthread_kill.c:89<br>
    #3  0x000073625aa4527e in __GI_raise (sig=sig@entry=6) at
    ../sysdeps/posix/raise.c:26<br>
    #4  0x000073625aa288ff in __GI_abort () at ./stdlib/abort.c:79<br>
    #5  0x00005a479e2f685f in ExceptionalCondition
    (conditionName=conditionName@entry=0x5a479e403cb8
    "entry-&gt;data.lockmode == BUFFER_LOCK_UNLOCK",
    fileName=fileName@entry=0x5a479e37a84f "bufmgr.c",
    lineNumber=lineNumber@entry=5908) at assert.c:65<br>
    #6  0x00005a479e14d87c in BufferLockConditional
    (buffer=&lt;optimized out&gt;, buf_hdr=0x73624e882b40,
    mode=mode@entry=BUFFER_LOCK_EXCLUSIVE) at bufmgr.c:5908<br>
    #7  0x00005a479e14f4d5 in ConditionalLockBuffer
    (buffer=buffer@entry=13500) at bufmgr.c:6474<br>
    #8  0x00005a479de44da9 in SpGistNewBuffer
    (index=index@entry=0x73625b1f6ce8) at spgutils.c:420<br>
    #9  0x00005a479de45397 in allocNewBuffer
    (index=index@entry=0x73625b1f6ce8, flags=flags@entry=3) at
    spgutils.c:528<br>
    #10 0x00005a479de456a0 in SpGistGetBuffer
    (index=index@entry=0x73625b1f6ce8, flags=flags@entry=3,
    needSpace=&lt;optimized out&gt;, needSpace@entry=4088,
    isNew=isNew@entry=0x7ffd8fa1b2a7) at spgutils.c:663<br>
    #11 0x00005a479de3c913 in doPickSplit
    (index=index@entry=0x73625b1f6ce8, state=state@entry=0x7ffd8fa1b740,
    current=current@entry=0x7ffd8fa1b510,
    parent=parent@entry=0x7ffd8fa1b530,
    newLeafTuple=newLeafTuple@entry=0x5a47cbd7adc8, level=level@entry=4,
    isNulls=false, isNew=false) at spgdoinsert.c:1046<br>
    #12 0x00005a479de3e542 in spgdoinsert
    (index=index@entry=0x73625b1f6ce8, state=state@entry=0x7ffd8fa1b740,
    heapPtr=heapPtr@entry=0x5a47cbe0b248,
    datums=datums@entry=0x7ffd8fa1b8d0,
    isnulls=isnulls@entry=0x7ffd8fa1b8b0) at spgdoinsert.c:2134<br>
    #13 0x00005a479de40137 in spginsert (index=0x73625b1f6ce8,
    values=0x7ffd8fa1b8d0, isnull=0x7ffd8fa1b8b0,
    ht_ctid=0x5a47cbe0b248, heapRel=&lt;optimized out&gt;,
    checkUnique=&lt;optimized out&gt;, indexUnchanged=false,
    indexInfo=0x5a47cbe0b0b8) at spginsert.c:206<br>
    #14 0x00005a479df981d8 in ExecInsertIndexTuples
    (resultRelInfo=resultRelInfo@entry=0x5a47cbe07120,
    slot=slot@entry=0x5a47cbe0b218, estate=estate@entry=0x5a47cbe06c10,
    update=update@entry=false, noDupErr=noDupErr@entry=false,
    specConflict=specConflict@entry=0x0, arbiterIndexes=0x0,
    onlySummarizing=false) at execIndexing.c:449<br>
    #15 0x00005a479dfcc6a9 in ExecInsert
    (context=context@entry=0x7ffd8fa1bb70,
    resultRelInfo=resultRelInfo@entry=0x5a47cbe07120,
    slot=slot@entry=0x5a47cbe0b218, canSetTag=&lt;optimized out&gt;,
    inserted_tuple=inserted_tuple@entry=0x0,
    insert_destrel=insert_destrel@entry=0x0) at nodeModifyTable.c:1240<br>
    #16 0x00005a479dfcdf67 in ExecModifyTable (pstate=0x5a47cbe06f10) at
    nodeModifyTable.c:4485<br>
    ...<br>
    <br>
    Best regards,<br>
    Alexander<br>
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