OEM agent is unhealthy with the following errors:

$ emctl status agent
Oracle Enterprise Manager Cloud Control 13c Release 4
Copyright (c) 1996, 2020 Oracle Corporation.  All rights reserved.
---------------------------------------------------------------
Status agent Failure:unable to connect to http server at https://racnode1:3872/emd/lifecycle/main/. [handshake has no peer]

$ emctl stop agent
Oracle Enterprise Manager Cloud Control 13c Release 4
Copyright (c) 1996, 2020 Oracle Corporation.  All rights reserved.

$ emctl pingOMS
Oracle Enterprise Manager Cloud Control 13c Release 4
Copyright (c) 1996, 2020 Oracle Corporation.  All rights reserved.
---------------------------------------------------------------
EMD pingOMS error: unable to connect to http server at https://racnode1:3872/emd/main/. [handshake has no peer]

Error stack observed from <Agent_Inst>/sysman/log/emagent.nohup file:

—– 2024-04-13 10:03:14,913::8313::Checking status of EMAgent : 10965 —–
—– 2024-04-13 10:03:14,913::8313::Hang detected for EMAgent : 10965 —–
—– 2024-04-13 10:03:14,913::8313::Debugging component EMAgent —–
—– 2024-04-13 10:03:14,913::generate first thread dump file for diagnosis —–
—– 2024-04-13 10:03:27,394::generate second thread dump file for diagnosis —–
—– 2024-04-13 10:03:27,592::generate Threads.10965lsof.1 for diagnosis —–
—– Attempting to kill EMAgent : 10965 —–
—– 2024-04-13 10:03:32,660::8313::EMAgent exited at 2024-04-13 10:03:32,660 with signal 9 —–
—– 2024-04-13 10:03:32,660::8313::EMAgent either hung or in abnormal state. —–
—– 2024-04-13 10:03:32,660::8313::EMAgent will be restarted/thrashed. —–
—– 2024-04-13 10:03:32,660::8313::writeAbnormalExitTimestampToAgntStmp: exitCause=ABNORMAL : restartRequired=1 —–
—– 2024-04-13 10:03:32,660::8313::Restarting EMAgent. —–
—– 2024-04-13 10:03:32,875::8313::Auto tuning the agent at time 2024-04-13 10:03:32,875 —–
—– 2024-04-13 10:03:40,237::8313::Finished auto tuning the agent at time 2024-04-13 10:03:40,237 —–
—– 2024-04-13 10:03:40,238::8313::Launching the JVM with following options: -Xmx128M -XX:MaxMetaspaceSize=224M -server -Djava.security.egd=file:///dev/./urandom -Dsun.lang.ClassLoader.allowArraySyntax=true -XX:-UseLargePages -XX:+UseLinuxPosixThreadCPUClocks -XX:+UseConcMarkSweepGC -XX:+CMSClassUnloadingEnabled -XX:+UseCompressedOops -DHTTPClient.dontSeekTerminatingChunk=true —–
—– 2024-04-13 10:03:40,239::8313::Agent Launched with PID 81582 at time 2024-04-13 10:03:40,239 —–
—– 2024-04-13 10:03:40,239::81582::Execing EMAgent process is taking longer than expected 120 secs —–
—– 2024-04-13 10:03:40,239::81582::Time elapsed between Launch of Watchdog process and execing EMAgent is 727958 secs —–

SOLUTION

1. Take the backup of the <Agent_Inst>/sysman/config/emd.properties file.

2. Update the following property as below:

agentJavaDefines=-Xmx128M -XX:MaxMetaspaceSize=224M

TO

agentJavaDefines=-Xmx512M -XX:MaxMetaspaceSize=224M

3. Save the file.

4. Try restarting the agent.
$ emctl stop agent
$ emctl start agent