Re: [Lambda]parallel sort stream slow than series sort

[Vladimir Yaroslavskiy]

> 
Hi,
 
Could you please check with OpenJDK version 14+?
Let us know the results.
 
Thank you,
Vladimir
 
>Date: Fri, 25 Sep 2020 18:09:57 +0800From: tonytao < tonytao0505 at outlook.com >
>To:  core-libs-dev at openjdk.java.net
>Subject: [Lambda]parallel sort stream slow than series sort
>
>hi,
>
>I wrote a test case to test stream performance,but the parallel sort
>always slow than the series sort.I test the data size in : 20,000 ,
>5,000,000, 10,000,000 , 20,000,000 .
>
>attatched is the test case source code.
>
>jdk version :
>
>openjdk version "11.0.8" 2020-07-14
>OpenJDK Runtime Environment (build 11.0.8+10-post-Debian-1deb10u1)
>OpenJDK 64-Bit Server VM (build 11.0.8+10-post-Debian-1deb10u1, mixed
>mode, sharing)
>
>jvm argument:
>
>-ea -Xms256m -Xmx8192m
>
>macheine:
>
>cpu:Intel(R) Core(TM) i7-8565U CPU @ 1.80GHz
>
>memory: 16GB
>
>Test? result shows as below:
>
>20000:
>
>sorted execute time:9ms, resultset rows 20000, 2222222 rows/sec
>parallel sorted execute time:24ms, resultset rows 20000, 833333 rows/sec
>
>5000000:
>
>sorted execute time:245ms, resultset rows 5000000, 20408163 rows/sec
>parallel sorted execute time:402ms, resultset rows 5000000, 12437810
>rows/sec
>
>10000000:
>
>sorted execute time:577ms, resultset rows 10000000, 17331022 rows/sec
>parallel sorted execute time:1230ms, resultset rows 10000000,  8130081
>rows/sec
>
>20000000:
>
>sorted execute time:1079ms, resultset rows 20000000, 18535681 rows/sec
>parallel sorted execute time:1790ms, resultset rows 20000000, 11173184
>rows/sec
>
>
>this is the test data sample:
>
>hdb=> select * from testdata limit 10;
> ?? id??? |?????????? uptime?????????? | x? | y? | cmt
>---------+----------------------------+----+----+----------------------------------
> ?1340417 | 2023-02-22 07:30:34.391207 | 33 |? 9 |
>4bf16d4c4b638d84b56893de2451c407
> ?1340418 | 2023-02-22 07:31:34.391207 | 10 | 91 |
>c9b78bfbd6b684e62605e96d2d8237a0
> ?1340419 | 2023-02-22 07:32:34.391207 | 66 | 24 |
>968e5d19ca3a2ddae5d2a366ba06cf16
> ?1340420 | 2023-02-22 07:33:34.391207 |? 4 | 42 |
>bdcf7d764121fc9b0039f80eadea1310
> ?1340421 | 2023-02-22 07:34:34.391207 | 27 | 45 |
>06520ac5e508f15f09672fa751d5c17a
> ?1340422 | 2023-02-22 07:35:34.391207 | 36 | 11 |
>5bede83b54dfe76f4a249308d8033691
> ?1340423 | 2023-02-22 07:36:34.391207 | 41 | 92 |
>37f4b34988c0e1387940177a8cc9d83a
> ?1340424 | 2023-02-22 07:37:34.391207 | 29 | 59 |
>416459b54ae00c95e118c93605a40d43
> ?1340425 | 2023-02-22 07:38:34.391207 |? 9 | 46 |
>46339b8eeae99c7e922003ed87b9d417
> ?1340426 | 2023-02-22 07:39:34.391207 | 21 | 29 |
>7ede63cdb2a6a86c63534fe5fcfb2f97
>(10 rows)
>
>
>It was generated by sql:
>
>create table testdata(
>     idint,
>     uptimetimestamp,
>     xint,
>     yint,
>     cmttext
>);
>insert into testdata
>     select
>         id,
>         uptime,
>         round(random()*100),
>         round(random()*100),
>         md5(uptime::text)
>     from (
>         select
>             generate_series id,
>             current_timestamp + make_interval(mins=> generate_series) uptime
>         from generate_series(1,100000000)
>         ) t;
>
>Could you please help me to find the problem?
>
>Thanks a lot.