PostgreSQL 11 preview - pgbench 支持大于1000链接(ppoll()代替select())

digoal 2018-03-25

202

作者

digoal

日期

2018-03-25

背景

目前pgbench最大可以测试1000个连接，显然在某些时候是不够的，我们可能需要建立更多的连接进行测试。

$ pgbench -j 3000 -c 1500 invalid number of clients: "1500"

使用这里提到的方法修改一下pgbench，让它能够建立100万个连接。

《从PostgreSQL支持100万个连接聊起》

PostgreSQL 11这块会改掉，使用ppoll代替select，超过1000个连接。

```
[trying again for 2018-01]

This patch enables building pgbench to use ppoll() instead of select()
to allow for more than (FD_SETSIZE - 10) connections. As implemented,
when using ppoll(), the only connection limitation is system resources.

The patch has been implemented to introduce a minimal of #ifdef/#ifndef
clutter in the code.

Without this patch, one is limited to '(FD_SETSIZE - 10)’ number of connections.
Example of something that fails without this patch but works with the patch:

Without the patch:

$ pgbench -j 3000 -c 1500
invalid number of clients: "1500"

With the patch:

$ pgbench -j 3000 -c 1500
starting vacuum...end.
transaction type:
scaling factor: 2000
query mode: simple
number of clients: 1500
number of threads: 1500
number of transactions per client: 10
number of transactions actually processed: 15000/15000
latency average = 631.730 ms
tps = 2374.430587 (including connections establishing)
tps = 4206.524986 (excluding connections establishing)