python3 sockmap.py -c "/sys/fs/cgroup/unified/"： The maximum transmission of a single socket stream is 2047M, and it starts to get stuck， why？

# question：
```
python3 sockmap.py -c "/sys/fs/cgroup/unified/"： The maximum transmission of a single socket stream is 2047M, and it starts to get stuck， why？
```

# description：
```
Ubuntu 21.04
kernel-5.9.11
clang-11
llvm-11
```
# error example
```
server：nginx listen 18080 port
client：
#python3 sockmap.py -c "/sys/fs/cgroup/unified/"
#curl http://127.0.0.1:18080/5g.b -v > /dev/null
39 5120M 39 2047M 0 0 91.0M 0 0:00:56 0:00:22 0:00:34 0
The maximum transmission of a single socket stream is 2047M, and it starts to get stuck， why？
close sockmap.py， curl can download successfully
```

Start by reproducing the transfer with python3 sockmap.py using /sys/fs/cgroup/unified/, curl, and the nginx server described in the issue. Compare the 5 GB download with sockmap.py enabled and disabled, using the stated Ubuntu 21.04, kernel 5.9.11, clang-11, and llvm-11 environment. Done means identifying the cause of the 2047M stall and documenting or correcting it.

Written by the indexing model from the issue text.