exceeds the defaultDepthLimit depth limit of the tree

[1037husterljx]

Bug report:

When the depth of candidateParent or peer is defaultDepthLimit (4), scheduling will fail no matter how and triggering RetryLimit returns 5006 error

Expected behavior:

Regardless of the depth, it should be possible to schedule successfully.

How to reproduce it:

Use 60 clients and three seed peers to start downloading 1G tasks at the same time, dyconfig loadlimit = 15

Environment:

• Dragonfly version: 059ee11ed702fd4f8d9fdcaab4f819f1d6449a26
• OS: linux
• Kernel (e.g. uname -a):
• Others: parentDepth+peerDepth > defaultDepthLimit is Unreasonable. One of the depths should be down to calculate the child depth.

[gaius-qi]

Quick Solution: Deletes the current peer depth calculation for the depth limit.

Future Solution: Task uses a DAG(Directed Acyclic Graph) for abstraction.