Backend Use Nacos cause OutOfMemoryError

[AYue-94]

What happened?

When backend loses contact with naocs, OOM occurs after a period of time：

Exception in thread "com.alibaba.nacos.client.Worker" java.lang.OutOfMemoryError: unable to create new native thread
	at java.lang.Thread.start0(Native Method)
	at java.lang.Thread.start(Thread.java:719)
	at java.util.concurrent.ThreadPoolExecutor.addWorker(ThreadPoolExecutor.java:957)
	at java.util.concurrent.ThreadPoolExecutor.processWorkerExit(ThreadPoolExecutor.java:1025)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1167)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
	at java.lang.Thread.run(Thread.java:750)
Exception in thread "com.alibaba.nacos.client.Worker" java.lang.OutOfMemoryError: unable to create new native thread
	at java.lang.Thread.start0(Native Method)
	at java.lang.Thread.start(Thread.java:719)
	at java.util.concurrent.ThreadPoolExecutor.addWorker(ThreadPoolExecutor.java:957)
	at java.util.concurrent.ThreadPoolExecutor.processWorkerExit(ThreadPoolExecutor.java:1025)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1167)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
	at java.lang.Thread.run(Thread.java:750)

jstack 6718 | grep "com.alibaba.nacos.client.Worker" | wc -l
    4029

How can we reproduce it (as minimally and precisely as possible)?

0. do not start nacos
1. backend use nacos

dynamic.config.enable=true
dynamic.config.namespace=sermant
dynamic.config.timeout=30000
dynamic.config.serverAddress=127.0.0.1:8848
dynamic.config.dynamicConfigType=NACOS
dynamic.config.connectTimeout=3000
dynamic.config.enableAuth=false
dynamic.config.userName=
dynamic.config.password=
dynamic.config.secretKey=

2. start backend

Anything else we need to know?

No response

Sermant version

2.0.0

OS version

MacOS

[AYue-94]

We don't need to manage reconnection owerself when using the Nacos client, nacos will deal reconnect itself.

for agent, it is the same, nacos version after 2.2.1（https://github.com/alibaba/nacos/pull/9639）, it add health check logic, it will cause memory/thread leak.

[AYue-94]

i will try to fix it, by remove nacos reconnect logic

[lilai23]

How many time nacosclient manages reconnection？Is it configurable？

[AYue-94]

The number of reconnections for nacos client cannot be configured, unlimited retries.
See https://github.com/alibaba/nacos/blob/2.2.1/common/src/main/java/com/alibaba/nacos/common/remote/client/RpcClient.java#L280