Re: WALWriteLocks

ok my bad,
it seems it was renamed,

WALWriteLock in 9,6 to WALWrite :)

so Yes, I do see WALWrite LWLocks.

Thanks,
Vijay

On Fri, 30 Apr 2021 at 01:30, Vijaykumar Jain <
vijaykumarjain(dot)github(at)gmail(dot)com> wrote:

> ok i have a small laptop with an even smaller vm :)
>
> pgbench -i s 3
> pgbench -c 20 -j 5 -T 900 -M prepared
>
> select wait_event_type, wait_event from pg_stat_activity;
>
> wait_event_type | wait_event
> -----------------+---------------------
> Activity | LogicalLauncherMain
> Activity | AutoVacuumMain
> LWLock | WALWrite
> Lock | transactionid
> Lock | tuple
> LWLock | WALWrite
> Lock | transactionid
> Lock | transactionid
> Lock | tuple
> Lock | transactionid
> Lock | transactionid
> Lock | transactionid
> Lock | tuple
> IO | WALSync
> Lock | transactionid
> |
> Activity | BgWriterHibernate
> Activity | CheckpointerMain
> LWLock | WALWrite
>
>
> i then destroyed the slow WAL db
> rm -rf data
>
>
> and built a new one without additional latency to WALdir.
>
> initdb -D data
> pg_ctl -D data start
>
> pgbench -i -s 3
> pgbench -c 20 -j 5 -T 900 -M prepared
>
> i see similar output as above
> but no
> WALWriteLock
>
> old thread, just for reference. do not read into anything :)
>
> PostgreSQL - hackers - An attempt to reduce WALWriteLock contention
> (postgresql-archive.org)
> <https://www.postgresql-archive.org/An-attempt-to-reduce-WALWriteLock-contention-td5935907.html>
>
>
> Thanks,
> Vijay
>
>
>
>
>
> On Fri, 30 Apr 2021 at 00:22, Laurenz Albe <laurenz(dot)albe(at)cybertec(dot)at>
> wrote:
>
>> On Fri, 2021-04-30 at 00:13 +0530, Vijaykumar Jain wrote:
>> > I tried the below, but i could not simulate WALWriteLock waits.
>> >
>> > create table foo(id int)
>> >
>> > for i in {1..10}; do psql -c "begin transaction; insert into foo
>> select 1 from generate_series(1, 1000); commit;" & done
>>
>> Perhaps you should do simple inserts of one row and run that script
>> with a pgbench and lots of clients.
>>
>> Yours,
>> Laurenz Albe
>> --
>> Cybertec | https://www.cybertec-postgresql.com
>>
>>