当多线程进程同时打开大量文件时，使用 lsof 命令来查看这些文件的打开情况可能会变得非常缓慢，并且会显著占用 CPU 资源。这主要是因为lsof在运行时需要遍历并列出所有线程所打开的文件，这一过程在文件数量庞大时会导致显著的延迟。
根据lsof的手册页描述，lsof命令提供了一个-K参数，该参数在某些系统上是始终启用的，并且不能被禁用。这意味着，lsof会默认列出所有线程及其打开的文件。手册页中关于-K参数的摘录如下：
-K selects the listing of tasks (threads) of processes, on dialects where task (thread) reporting is supported. (If help output - i.e., the output of the -h or -? options - shows this option, then task (thread) reporting is supported by the dialect.)
When -K and -a are both specified on Linux, and the tasks of a main process are selected by other options, the main process will also be listed as though it were a task, but without a task ID. (See the description of the TID column in the OUTPUT section.)
Where the FreeBSD version supports threads, all threads will be listed with their IDs.
In general threads and tasks inherit the files of the caller, but may close some and open others, so lsof always reports all the open files of threads and tasks.
解决方案
使用选项-Ki忽略显示相同数据的多个线程。
总结
综上所述，虽然 lsof 是一个功能强大的工具，但在处理多线程进程和大量文件打开情况时，可能会遇到性能瓶颈。因此，在使用时需要权衡其功能和性能需求。
原创文章，作者：运维侠，如若转载，请注明出处：https://www.yunweixia.com/knowledgebase/lsof-command-usage-tips-how-to-avoid-performance-issues-in-multi-threaded-processes.html
微信扫一扫 
支付宝扫一扫 
