寻找第一个瓶颈
通过查看第一个图表我们注意到的一些信息是：
A few things we notice by looking at this first diagram are:
- 在左边的 mongodb 气泡里花了很多时间。
1.A lot of time is spent inside the mongodb bubble on the left.
- 底部的查询气泡在查询时花费了差不多的时间。
2.Similar amount of time is spent querying in the query bubble at the bottom.
- 时间轴稀疏，表明吞吐量低。
3.The timeline is sparse indicating low throughput.
这似乎是吞吐量问题，并且可能与mongodb有关。
This seems like a throughput problem, likely related to mongodb.
如果我们查看数据库设置，会注意到服务器正在使用不包含索引的集合。
If we investigate the database setup we notice that the server is using a collection that doesn't contain an index.
这意味着数据库每次都必须循环所有数据来响应我们的查询，从而产生大量的数据库延迟。
This means the database has to iterate all the data every time to answer our query, which creates a lot of database latency.
我们可以通过在我们使用的属性上添加索引来减少这种开销。
We can reduce this overhead by adding an index on the properties we use.