Re: [HACKERS] Block level parallel vacuum

Hi,

While testing this feature with parallel vacuum on "TEMPORARY TABLE", I got
a server crash on PG Head+V36_patch.
Changed configuration parameters and Stack trace are as below:

autovacuum = on
max_worker_processes = 4
shared_buffers = 10MB
max_parallel_workers = 8
max_parallel_maintenance_workers = 8
vacuum_cost_limit = 2000
vacuum_cost_delay = 10
min_parallel_table_scan_size = 8MB
min_parallel_index_scan_size = 0

-- Stack trace:
[centos(at)parallel-vacuum-testing bin]$ gdb -q -c data/core.1399 postgres
Reading symbols from
/home/centos/BLP_Vacuum/postgresql/inst/bin/postgres...done.
[New LWP 1399]
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib64/libthread_db.so.1".
Core was generated by `postgres: autovacuum worker postgres
'.
Program terminated with signal 6, Aborted.
#0 0x00007f4517d80337 in raise () from /lib64/libc.so.6
Missing separate debuginfos, use: debuginfo-install
glibc-2.17-292.el7.x86_64 keyutils-libs-1.5.8-3.el7.x86_64
krb5-libs-1.15.1-37.el7_7.2.x86_64 libcom_err-1.42.9-16.el7.x86_64
libgcc-4.8.5-39.el7.x86_64 libselinux-2.5-14.1.el7.x86_64
openssl-libs-1.0.2k-19.el7.x86_64 pcre-8.32-17.el7.x86_64
zlib-1.2.7-18.el7.x86_64
(gdb) bt
#0 0x00007f4517d80337 in raise () from /lib64/libc.so.6
#1 0x00007f4517d81a28 in abort () from /lib64/libc.so.6
#2 0x0000000000a96341 in ExceptionalCondition (conditionName=0xd18efb
"strvalue != NULL", errorType=0xd18eeb "FailedAssertion",
fileName=0xd18ee0 "snprintf.c", lineNumber=442) at assert.c:67
#3 0x0000000000b02522 in dopr (target=0x7ffdb0e38450, format=0xc5fa95
".%s\"", args=0x7ffdb0e38538) at snprintf.c:442
#4 0x0000000000b01ea6 in pg_vsnprintf (str=0x256df50 "autovacuum: dropping
orphan temp table \"postgres.", '\177' <repeats 151 times>..., count=1024,
fmt=0xc5fa68 "autovacuum: dropping orphan temp table \"%s.%s.%s\"",
args=0x7ffdb0e38538) at snprintf.c:195
#5 0x0000000000afbadf in pvsnprintf (buf=0x256df50 "autovacuum: dropping
orphan temp table \"postgres.", '\177' <repeats 151 times>..., len=1024,
fmt=0xc5fa68 "autovacuum: dropping orphan temp table \"%s.%s.%s\"",
args=0x7ffdb0e38538) at psprintf.c:110
#6 0x0000000000afd34b in appendStringInfoVA (str=0x7ffdb0e38550,
fmt=0xc5fa68 "autovacuum: dropping orphan temp table \"%s.%s.%s\"",
args=0x7ffdb0e38538)
at stringinfo.c:149
#7 0x0000000000a970fd in errmsg (fmt=0xc5fa68 "autovacuum: dropping orphan
temp table \"%s.%s.%s\"") at elog.c:832
#8 0x00000000008588d2 in do_autovacuum () at autovacuum.c:2249
#9 0x0000000000857b29 in AutoVacWorkerMain (argc=0, argv=0x0) at
autovacuum.c:1689
#10 0x000000000085772f in StartAutoVacWorker () at autovacuum.c:1483
#11 0x000000000086e64f in StartAutovacuumWorker () at postmaster.c:5562
#12 0x000000000086e106 in sigusr1_handler (postgres_signal_arg=10) at
postmaster.c:5279
#13 <signal handler called>
#14 0x00007f4517e3f933 in __select_nocancel () from /lib64/libc.so.6
#15 0x0000000000869838 in ServerLoop () at postmaster.c:1691
#16 0x0000000000869212 in PostmasterMain (argc=3, argv=0x256bd70) at
postmaster.c:1400
#17 0x000000000077855d in main (argc=3, argv=0x256bd70) at main.c:210
(gdb)

I have tried to reproduce the same with all previously executed queries but
now I am not able to reproduce the same.

On Thu, Dec 19, 2019 at 11:26 AM Mahendra Singh <mahi6run(at)gmail(dot)com> wrote:

> On Wed, 18 Dec 2019 at 12:07, Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
> >
> > [please trim extra text before responding]
> >
> > On Wed, Dec 18, 2019 at 12:01 PM Mahendra Singh <mahi6run(at)gmail(dot)com>
> wrote:
> > >
> > > On Tue, 10 Dec 2019 at 00:30, Mahendra Singh <mahi6run(at)gmail(dot)com>
> wrote:
> > > >
> > > >
> > > > 3.
> > > > After v35 patch, vacuum.sql regression test is taking too much time
> due to large number of inserts so by reducing number of tuples, we can
> reduce that time.
> > > > +INSERT INTO pvactst SELECT i, array[1,2,3], point(i, i+1) FROM
> generate_series(1,100000) i;
> > > >
> > > > here, instead of 100000, we can make 1000 to reduce time of this
> test case because we only want to test code and functionality.
> > >
> > > As we added check of min_parallel_index_scan_size in v36 patch set to
> > > decide parallel vacuum, 1000 tuples are not enough to do parallel
> > > vacuum. I can see that we are not launching any workers in vacuum.sql
> > > test case and hence, code coverage also decreased. I am not sure that
> > > how to fix this.
> > >
> >
> > Try by setting min_parallel_index_scan_size to 0 in test case.
>
> Thanks Amit for the fix.
>
> Yes, we can add "set min_parallel_index_scan_size = 0;" in vacuum.sql
> test case. I tested by setting min_parallel_index_scan_size=0 and it
> is working fine.
>
> @Masahiko san, please add above line in vacuum.sql test case.
>
> Thanks and Regards
> Mahendra Thalor
> EnterpriseDB: http://www.enterprisedb.com
>
>
>

--

With Regards,

Prabhat Kumar Sahu
Skype ID: prabhat.sahu1984
EnterpriseDB Software India Pvt. Ltd.

The Postgres Database Company