Fly on the Set

In practice, the amount of memory set aside for survivor space is adjusted on the fly depending on the percentage of objects that survive each collection.

实际上，预留为幸存者空间的内存量会根据在每次收集中幸存下来的对象的百分比进行实时调整。

The video chat feature lets you set up multi-person conferences on the fly.

视频聊天的功能可以让你在飞机上召开多人会议.

If your interface USES a lot of dynamic menu updates, it might be better to create a set of menu bars and switch between them, rather than updating them on the fly all the time.

如果界面使用了很多动态菜单更新，创建一组菜单条并在它们之间切换而不是一直动态地更新它们也许会更好一些。