AttributeCollection[Type type] uses a static lock; prevents Type from being unloaded

[seanhalliday]

Description

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Issue Details

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Description

Author:	seanhalliday
Assignees:	-
Labels:	area-System.ComponentModel, tenet-performance, untriaged
Milestone:	-

[huoyaoyuan]

The only static state to protect is s_defaultAttributes, which is already protected in GetDefaultAttribute. It should really be a ConditionalWeakTable in order to support collectible types.

[steveharter]

Code:

runtime/src/libraries/System.ComponentModel.TypeConverter/src/System/ComponentModel/AttributeCollection.cs

Line 27 in 49a8bb7

private static readonly object s_internalSyncObject = new object();

[steveharter]

The only static state to protect is s_defaultAttributes, which is already protected in GetDefaultAttribute

Yes s_internalSyncObject is used in part to protect s_defaultAttributes so using a static makes sense.

It should really be a ConditionalWeakTable in order to support collectible types.

Is the underlying concern\issue around unloadable types?

[huoyaoyuan]

Is the underlying concern\issue around unloadable types?

The Type and attribute instance will permanently stay in the s_defaultAttributes dictionary. This prevents the type and the assembly to be collected.