agent can not reconnect to the collector when the oap server have only one instance and has been restarted

[yefei14131]

Please answer these questions before submitting your issue.

• Why do you submit this issue?
• Question or discussion
• Bug
• Requirement
• Feature or performance improvement

---

Bug

• Which version of SkyWalking, OS and JRE?
  version: v6.3.0
• Which company or project?
  hualala.com
• What happen?
  agent can not reconnect to the collector when the oap server only one instance and has been restarted.

source code in class org.apache.skywalking.apm.agent.core.remote.GRPCChannelManager:

try {
    int index = Math.abs(random.nextInt()) % grpcServers.size();
    if (index != selectedIdx) {
        selectedIdx = index;

        server = grpcServers.get(index);
        String[] ipAndPort = server.split(":");

        if (managedChannel != null) {
            managedChannel.shutdownNow();
        }

        managedChannel = GRPCChannel.newBuilder(ipAndPort[0], Integer.parseInt(ipAndPort[1]))
            .addManagedChannelBuilder(new StandardChannelBuilder())
            .addManagedChannelBuilder(new TLSChannelBuilder())
            .addChannelDecorator(new AgentIDDecorator())
            .addChannelDecorator(new AuthenticationDecorator())
            .build();

        notify(GRPCChannelStatus.CONNECTED);
        reconnect = false;
    } else if (managedChannel.isConnected()) {
        // Reconnect to the same server is automatically done by GRPC,
        // therefore we are responsible to check the connectivity and
        // set the state and notify listeners
        notify(GRPCChannelStatus.CONNECTED);
        reconnect = false;
    }

    return;
} catch (Throwable t) {
    logger.error(t, "Create channel to {} fail.", server);
}

the line 102 in class org.apache.skywalking.apm.agent.core.remote.GRPCChannelManager should be channge to :

if (index != selectedIdx || !managedChannel.isConnected())

[kezhenxu94]

Duplicate of #3366

[kezhenxu94]

The bug should be fixed in 6.3.0, #3181 and #3240 @yefei14131