How to troubleshoot high memory usage in Linux?

To investigate the high memory usage in a Linux system, you can follow these steps:

1. Check the system’s current memory usage by using the command top or htop. These commands can display the memory usage of various processes in the system and sort them based on memory usage.
2. Based on the output from top or htop, identify the process with the highest memory usage. Pay attention to the RES (Resident Set Size) field, which shows the actual physical memory size used by the process.
3. Check the detailed information of the process using the command “ps aux” or “ps -ef”, including the process command line parameters, start time, parent process, etc.
4. To view the memory mapping situation of a process, use the command pmap -x followed by the process ID. The pmap command can display the memory mapping areas of a process, including shared libraries, heap, and stack.
5. Using the output of pmap, identify the memory mapping areas that occupy the most memory, focusing on the shared libraries and heap sections. Shared libraries may be shared by multiple processes, while the heap is the memory space used by the process itself.
6. Use the command lsof -p to check the files and file descriptors opened by the process. These files may be taking up a lot of memory resources.
7. Analyze the reasons for high memory usage based on the results of the above steps. Possible reasons include process leaks, memory leaks, excessive loading of shared libraries, and a large number of open files.
8. Based on the analysis results, appropriate measures will be taken to resolve the issue of high memory usage. This can involve adjusting process configuration parameters, optimizing code, reducing the loading of shared libraries, and closing unnecessary files.

It is important to note that memory usage in Linux systems is dynamic and can be adjusted and optimized based on actual needs. High memory usage may not necessarily be a problem, as it could be the system using a lot of cache to improve performance. Therefore, when troubleshooting high memory usage issues, it is important to consider the system’s actual situation and performance requirements.