Re: waiting for client write

Pavan,

In jProfiler , I see that most cpu is consumed when the Tomcat thread is
stuck at PgPreparedStatement.execute. I am using version 42.2.16 of JDBC
driver.

Ranier,

EXPLAIN ANALYZE

SELECT a.menu_item_id, a.menu_item_name, a.menu_item_category_id,
b.menu_item_category_desc, c.menu_item_variant_id,
c.menu_item_variant_type_id, c.price, c.size_id,
c.parent_menu_item_variant_id, d.menu_item_variant_type_desc,
e.size_desc, f.currency_code, a.image, a.mark_id, m.mark_name

FROM menu_item_category AS b, menu_item_variant AS c,
menu_item_variant_type AS d, item_size AS e, restaurant AS f,
menu_item AS a

LEFT OUTER JOIN mark AS m ON (a.mark_id = m.mark_id) WHERE
a.menu_item_category_id = b.menu_item_category_id AND a.menu_item_id =
c.menu_item_id AND c.menu_item_variant_type_id =
d.menu_item_variant_type_id AND d.is_hidden = 'false' AND c.size_id =
e.size_id AND a.restaurant_id = f.restaurant_id AND f.restaurant_id =
1528 AND (a.menu_item_category_id = NULL OR NULL IS NULL)

AND c.menu_item_variant_id = (SELECT min(menu_item_variant_id) FROM
menu_item_variant WHERE menu_item_id = a.menu_item_id AND deleted =
'N' limit 1) AND a.active = 'Y'
AND (CONCAT_WS('', ',', a.hidden_branch_ids, ',') NOT LIKE
CONCAT_WS('', '%,4191,%') OR NULL IS NULL)
AND is_menu_item_available(a.menu_item_id, 'Y') = 'Y'

Nested Loop Left Join (cost=5.15..162.10 rows=1 width=148) (actual
time=0.168..5.070 rows=89 loops=1)
Join Filter: (a.mark_id = m.mark_id)
Rows Removed by Join Filter: 267
-> Nested Loop (cost=5.15..161.04 rows=1 width=144) (actual
time=0.161..4.901 rows=89 loops=1)
-> Nested Loop (cost=4.86..158.72 rows=1 width=148) (actual
time=0.156..4.729 rows=89 loops=1)
-> Nested Loop (cost=4.57..158.41 rows=1 width=140)
(actual time=0.151..4.572 rows=89 loops=1)
-> Nested Loop (cost=4.28..158.10 rows=1
width=132) (actual time=0.145..4.378 rows=89 loops=1)
-> Nested Loop (cost=0.71..152.51 rows=1
width=95) (actual time=0.121..3.334 rows=89 loops=1)
-> Index Scan using
menu_item_restaurant_id on menu_item a (cost=0.42..150.20 rows=1
width=83) (actual time=0.115..3.129 rows=89 loops=1)
Index Cond: (restaurant_id = 1528)
" Filter: ((active = 'Y'::bpchar)
AND (is_menu_item_available(menu_item_id, 'Y'::bpchar) =
'Y'::bpchar))"
Rows Removed by Filter: 194
-> Index Scan using
menu_item_category_pk on menu_item_category b (cost=0.29..2.31 rows=1
width=20) (actual time=0.002..0.002 rows=1 loops=89)
Index Cond:
(menu_item_category_id = a.menu_item_category_id)
-> Index Scan using menu_item_variant_pk on
menu_item_variant c (cost=3.57..5.59 rows=1 width=45) (actual
time=0.002..0.002 rows=1 loops=89)
Index Cond: (menu_item_variant_id = (SubPlan 1))
Filter: (a.menu_item_id = menu_item_id)
SubPlan 1
-> Limit (cost=3.13..3.14 rows=1
width=8) (actual time=0.008..0.008 rows=1 loops=89)
-> Aggregate
(cost=3.13..3.14 rows=1 width=8) (actual time=0.008..0.008 rows=1
loops=89)
-> Index Scan using
"idx$$_023a0001" on menu_item_variant (cost=0.43..3.11 rows=8
width=8) (actual time=0.003..0.007 rows=7 loops=89)
Index Cond:
(menu_item_id = a.menu_item_id)
Filter: (deleted =
'N'::bpchar)
Rows Removed by Filter: 4
-> Index Scan using menu_item_variant_type_pk on
menu_item_variant_type d (cost=0.29..0.31 rows=1 width=16) (actual
time=0.002..0.002 rows=1 loops=89)
Index Cond: (menu_item_variant_type_id =
c.menu_item_variant_type_id)
Filter: ((is_hidden)::text = 'false'::text)
-> Index Scan using size_pk on item_size e
(cost=0.29..0.31 rows=1 width=16) (actual time=0.001..0.001 rows=1
loops=89)
Index Cond: (size_id = c.size_id)
-> Index Scan using "restaurant_idx$$_274b003d" on restaurant
f (cost=0.29..2.30 rows=1 width=12) (actual time=0.001..0.001 rows=1
loops=89)
Index Cond: (restaurant_id = 1528)
-> Seq Scan on mark m (cost=0.00..1.03 rows=3 width=12) (actual
time=0.000..0.001 rows=3 loops=89)
Planning Time: 2.078 ms
Execution Time: 5.141 ms

On Wed, Jun 9, 2021 at 5:47 PM Ayub Khan <ayub(dot)hp(at)gmail(dot)com> wrote:

> attached is the screenshot of RDS performance insights for AWS and it
> shows high waiting client writes. The api performance is slow. I read that
> this might be due to IOPS on RDS. However we have 80k IOPS on this test
> RDS.
>
> Below is the query which is being load tested
>
> SELECT
>
> a.menu_item_id,
> a.menu_item_name,
> a.menu_item_category_id,
> b.menu_item_category_desc,
> c.menu_item_variant_id,
> c.menu_item_variant_type_id,
> c.price,
> c.size_id,
> c.parent_menu_item_variant_id,
> d.menu_item_variant_type_desc,
> e.size_desc,
> f.currency_code,
> a.image,
> a.mark_id,
> m.mark_name
>
> FROM .menu_item_category AS b, .menu_item_variant AS
> c,
> .menu_item_variant_type AS d, .item_size AS e,
> .restaurant AS f,
> .menu_item AS a
>
> LEFT OUTER JOIN .mark AS m
> ON (a.mark_id = m.mark_id)
>
> WHERE a.menu_item_category_id =
> b.menu_item_category_id AND a.menu_item_id = c.menu_item_id AND
> c.menu_item_variant_type_id =
> d.menu_item_variant_type_id AND d.is_hidden = 'false' AND
> c.size_id = e.size_id AND a.restaurant_id =
> f.restaurant_id AND f.restaurant_id = 1528 AND
> (a.menu_item_category_id = NULL OR NULL IS NULL)
>
> AND c.menu_item_variant_id = (SELECT
> min(menu_item_variant_id)
> FROM
> .menu_item_variant
> WHERE
> menu_item_id = a.menu_item_id AND deleted = 'N'
> LIMIT 1) AND
> a.active = 'Y'
> AND (CONCAT_WS('', ',', a.hidden_branch_ids,
> ',') NOT LIKE CONCAT_WS('', '%,4191,%') OR
> NULL IS NULL)
> AND .is_menu_item_available(a.menu_item_id, 'Y') = 'Y'
>
> ORDER BY a.row_order, menu_item_id;
>
> --Ayub
>

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