Gin c.DefaultPostForm may cause block

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Description

I use function c.DefaultPostForm to get token param in the middleware, it cause a long time block with a slight possibility.

How to reproduce

func CheckTokenPro() gin.HandlerFunc {
    return func(c *gin.Context) {
        var token string
        start := time.Now()
        token = c.DefaultPostForm("token", "")
        cost := time.Since(start).Seconds()
        if cost > 3 {
            logging.Info(fmt.Sprintf("CheckTokenPro：%.2f秒", cost))
        }

        c.Next()
    }
}

Expectations

Actual result

Environment

• go version: 1.14.7
• gin version (or commit ref): gin v1.6.3
• operating system: linux

Comment From: mi-v

c.DefaultPostForm calls out to req.ParseMultipartForm, documentation of which says:

The whole request body is parsed and up to a total of maxMemory bytes of its file parts are stored in memory, with the remainder stored on disk in temporary files.

Which means that it has to read the whole request body from the network, and this may take some time depending on the request size and network speed.