[Dubbo-4556] fix dubbo startup is slow

[crossoverJie]

What is the purpose of the change

fix #4556

Brief changelog

modify:dubbo/dubbo-config/dubbo-config-api/src/main/java/org/apache/dubbo/config/ServiceConfig.java

[codecov-io]

Codecov Report

Merging #4603 into master will decrease coverage by 0.26%.
The diff coverage is 100%.

@@             Coverage Diff              @@
##             master    #4603      +/-   ##
============================================
- Coverage     64.17%   63.91%   -0.27%     
+ Complexity      453      449       -4     
============================================
  Files           768      769       +1     
  Lines         32869    33160     +291     
  Branches       5179     5226      +47     
============================================
+ Hits          21094    21193      +99     
- Misses         9358     9545     +187     
- Partials       2417     2422       +5

Impacted Files	Coverage Δ	Complexity Δ
...in/java/org/apache/dubbo/config/ServiceConfig.java	59.14% <100%> (+0.72%)	0 <0> (ø)	⬇️
.../apache/dubbo/qos/protocol/QosProtocolWrapper.java	64.1% <0%> (-17.95%)	0% <0%> (ø)
...e/dubbo/remoting/transport/netty/NettyChannel.java	54.11% <0%> (-8.24%)	19% <0%> (-2%)
...apache/dubbo/rpc/protocol/dubbo/FutureAdapter.java	53.84% <0%> (-7.7%)	0% <0%> (ø)
...beans/factory/annotation/ReferenceBeanBuilder.java	68% <0%> (-7%)	0% <0%> (ø)
...ng/transport/dispatcher/all/AllChannelHandler.java	51.42% <0%> (-5.72%)	0% <0%> (ø)
.../org/apache/dubbo/remoting/ExecutionException.java	15.78% <0%> (-5.27%)	0% <0%> (ø)
.../apache/dubbo/remoting/transport/AbstractPeer.java	63.04% <0%> (-4.35%)	0% <0%> (ø)
...g/p2p/exchange/support/MulticastExchangeGroup.java	72.34% <0%> (-4.26%)	0% <0%> (ø)
...mmon/serialize/kryo/utils/AbstractKryoFactory.java	75% <0%> (-3.58%)	0% <0%> (ø)
... and 35 more

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[tswstarplanet]

The pr alarm user that getting ip is too slow by log ?

[crossoverJie]

Yes, I've seen a Dubbo service take two hours to start.

See here for more information:
https://crossoverjie.top/2019/07/05/troubleshoot/dubbo-start-slow/

Of course, we can also add a timeout period, and once the timeout occurs,
the service start fails.

[beiwei30]

I cannot agree with this solution, since it does nothing useful but keep printing out the warning message every 10 secs.

Instead of doing this, why don't we simply put more logging messages for this method?

logger.info(hostToBind + " is not valid local host, try to find valid host from DNS.");
hostToBind = InetAddress.getLocalHost().getHostAddress();

[crossoverJie]

I cannot agree with this solution, since it does nothing useful but keep printing out the warning message every 10 secs.

Instead of doing this, why don't we simply put more logging messages for this method?

logger.info(hostToBind + " is not valid local host, try to find valid host from DNS.");
hostToBind = InetAddress.getLocalHost().getHostAddress();

I think the root cause of this problem is that once the response is slow due to InetAddress.getLocalHost().getHostAddress(), the user does not know where to find the problem.

For logs printed every 10s, we can add some help to find the problem; for example: check DNS server or configure /etc/hosts.

Although the reason for executing InetAddress.getLocalHost().getHostAddress() is also caused by an invalid address, I don't think it can help the user find the problem quickly.

[chickenlj]

I agree with the idea suggested by @beiwei30.

try to find a valid host from DNS... would be enough to warn the user where the problem is once the process hangs, that's the last message the user can see and obviously searching DNS is very likely to be a blocking operation.

[crossoverJie]

@beiwei30 @chickenlj

Thank you for your advice.

Now think about adding a thread for a small probability event, it is too heavy.

I have revised it again.

[beiwei30]

LGTM.

[beiwei30]

I can merge it once CI passes.