top -H -p

top连接参数说明

-H  :Threads-mode operation
     Instructs top to display individual threads.  Without this command-line option a summation of all threads in each process is shown.  Later this can be changed with the `H' interactive command.

-p  :Monitor-PIDs mode as:  -pN1 -pN2 ...  or  -pN1,N2,N3 ...
    Monitor only processes with specified process IDs.  This option can be given up to 20 times, or you can provide a comma delimited list with up to 20 pids.  Co-mingling both approaches is permitted.

查看某个进程内部线程占用情况分析:
top -H -p 18605