On Mon, Sep 5, 2016 at 9:33 AM, Amit Kapila <amit.kapila16@gmail.com> wrote:
> USE_CONTENT_LOCK on my windows box, you can try by commenting that as
> well, if it works for you). So, in short we have to compare three
> approaches here.
>
> 1) Group mode to reduce CLOGControlLock contention
> 2) Use granular locking model
> 3) Use atomic operations
I have tested performance with approach 1 and approach 2.
1. Transaction (script.sql): I have used below transaction to run my
bench mark, We can argue that this may not be an ideal workload, but I
tested this to put more load on ClogControlLock during commit
transaction.
-----------
\set aid random (1,30000000)
\set tid random (1,3000)
BEGIN;
SELECT abalance FROM pgbench_accounts WHERE aid = :aid for UPDATE;
SAVEPOINT s1;
SELECT tbalance FROM pgbench_tellers WHERE tid = :tid for UPDATE;
SAVEPOINT s2;
SELECT abalance FROM pgbench_accounts WHERE aid = :aid for UPDATE;
END;
-----------
2. Results
./pgbench -c $threads -j $threads -T 10 -M prepared postgres -f script.sql
scale factor: 300
Clients head(tps) grouplock(tps) granular(tps)
------- --------- ---------- -------
128 29367 39326 37421
180 29777 37810 36469
256 28523 37418 35882
grouplock --> 1) Group mode to reduce CLOGControlLock contention
granular --> 2) Use granular locking model
I will test with 3rd approach also, whenever I get time.
3. Summary:
1. I can see on head we are gaining almost ~30 % performance at higher
client count (128 and beyond).
2. group lock is ~5% better compared to granular lock.
--
Regards,
Dilip Kumar
EnterpriseDB: http://www.enterprisedb.com