reduce link threads to avoid OOM

[cangfengzhs]

What type of PR is this?

• bug
• feature
• enhancement

What problem(s) does this PR solve?

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Description:

How do you solve it?

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Tests:

• Unit test(positive and negative cases)
• Function test
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• Documentation affected (Please add the label if documentation needs to be modified.)
• Incompatibility (If it breaks the compatibility, please describe it and add the label.）
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• Performance impacted: Consumes more CPU/Memory

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ex. Fixed the bug .....