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Question by wangcy974 · Oct 03, 2014 at 03:14 AM · getcomponent

GetComponent Makes 0.5K GC

There is a gameObject and a Script "B",I want to use GetComponent,the Script "B" is not on the gameObject, so it will make 0.5k GC, how can I do?I want to judge if the gameObject has Script "B".

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Answer by rutter · Oct 03, 2014 at 03:17 AM

This is only an issue when you run in the editor.

Running a built player? GetComponent will return null, as documented.

Running in the editor? GetComponent will allocate some memory to generate a special MissingComponentException with their "custom null" object.

Quoting a post from the Unity blog:

We do this in the editor only. This is why when you call GetComponent() to query for a component that doesn’t exist, that you see a C# memory allocation happening, because we are generating this custom warning string inside the newly allocated fake null object. This memory allocation does not happen in built games. This is a very good example why if you are profiling your game, you should always profile the actual standalone player or mobile player, and not profile the editor, since we do a lot of extra security / safety / usage checks in the editor to make your life easier, at the expense of some performance. When profiling for performance and memory allocations, never profile the editor, always profile the built game.

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avatar image wangcy974 · Oct 15, 2014 at 03:13 AM 0
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thank you!

avatar image yoyo · Oct 01, 2015 at 10:16 PM 0
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It's a pity you can't pre-allocate and reuse a single one of these "fake null objects". Would that be possible?

avatar image Bunny83 yoyo · Oct 06, 2015 at 11:15 AM 0
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I think from a pure technical point of view i think that should be possible. However i'm not sure what happens when you pass this object to Destroy or DestroyImmediate. I would guess nothing should happen since every UnityEngine.Object instance becomes a fake null object once you destroy it. The Unity editor already uses tons of static cache variables for so many internal things, this one wouldn't hurt i guess ^^.

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