Run the following commands to troubleshoot the error of excessive memory usage:

1. Run the top command to query the realtime memory usage of processes.

2. Run the free -m or cat /proc/meminfo command to view the total memory usage.

3. Run the vmstat command to query statistics on the virtual memory.

4. Run the ps aux --sort=-%mem command to sort all processes by memory usage.

5. Run the lsof | grep malloc command to view the files and processes currently consuming memory resources.

6. Run the grep -i "cache" /proc/meminfo command to view the memory usage of caches.

Run the above commands to find the root cause of excessive memory usage. If the root cause is a process, you can optimize or restart the process. If the root cause is insufficient memory space (which leads to system performance degradation), you can expand physical memory or reduce system memory usage.