[Bug]: fatal error: concurrent map read and map write

[iqinlongfei]

Actions I've taken before I'm here

• I've thoroughly read the documentations on this issue but still have no clue.
• I've searched the Github Issues but didn't find any duplicate issues that have been resolved.
• I've searched the internet for this issue but didn't find anything helpful.

What happened?

Major version of gnet

v2

Specific version of gnet

v2.3.3

Operating system

Linux

OS version

Linux 5.15.56.bsk.1-amd64 x86_64

Go version

go1.19.2

Relevant log output

fatal error: concurrent map read and map write

goroutine 398788 [running]:
github.com/panjf2000/gnet/v2.(*connMatrix).getConn(...)
	/go/pkg/mod/github.com/panjf2000/gnet/v2@v2.3.3/conn_map.go:66
github.com/panjf2000/gnet/v2.(*eventloop).close(0xc354050380, 0xc4d02c3960, {0x1099680, 0xc50f578860})
	/go/pkg/mod/github.com/panjf2000/gnet/v2@v2.3.3/eventloop_unix.go:174 +0xc5
github.com/panjf2000/gnet/v2.(*conn).write(0xc4d02c3960, {0xc4b0751b30, 0xee, 0xee})
	/go/pkg/mod/github.com/panjf2000/gnet/v2@v2.3.3/connection_unix.go:137 +0x165
github.com/panjf2000/gnet/v2.(*conn).Write(0xc483353680?, {0xc4b0751b30?, 0x0?, 0x0?})
	/go/pkg/mod/github.com/panjf2000/gnet/v2@v2.3.3/connection_unix.go:353 +0x5b

Code snippets (optional)

No response

How to Reproduce

Steps to reproduce the behavior:

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2. Click on '....'
3. Do '....'
4. See '....'

Does this issue reproduce with the latest release?

It can reproduce with the latest release

[panjf2000]

Did you call some APIs that are not concurrency-safe outside the eventloop? Please provide a reproducer for this issue.