如何查看某个进程的具体线程信息？

答案：一个线程必定属于也只能属于一个进程；而一个进程可以拥有多个线程并且至少拥有一个线程。线程又被称为轻量级进程（Light Weight Process，LWP）。进程有进程控制块，线程也有线程控制块。但线程控制块比进程控制块小得多。线程间切换代价小，进程间切换代价大。每个进程都有独立的内存空间，而线程共享其所属进程的内存空间。

pstree -p pid

ps -eLf | grep pid

ps -Lf pid

pstack pid

top -Hp pid

通过“cat proc/pid/status”可以查看某个进程的进程状态信息。

[root@LHRDB ~]# top -Hp 16833

top - 10:00:28 up 10:00,  2 users,  load average: 0.00, 0.00, 0.00

Tasks:  29 total,   0 running,  29 sleeping,   0 stopped,   0 zombie

Cpu(s):  0.0%us,  0.0%sy,  0.0%ni,100.0%id,  0.0%wa,  0.0%hi,  0.0%si,  0.0%st

Mem:   2046592k total,  1937088k used,   109504k free,   119212k buffers

Swap:  2097144k total,      304k used,  2096840k free,   977856k cached

 

  PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND                                                                                                                                              

16833 mysql     20   0 1155m 188m  11m S  0.0  9.4   0:00.16 mysqld                                                                                                                                               

16834 mysql     20   0 1155m 188m  11m S  0.0  9.4   0:00.00 mysqld                                                                                                                                               

16836 mysql     20   0 1155m 188m  11m S  0.0  9.4   0:00.23 mysqld                                                                                                                                               

16837 mysql     20   0 1155m 188m  11m S  0.0  9.4   0:00.30 mysqld                                                                                                                                               

16838 mysql     20   0 1155m 188m  11m S  0.0  9.4   0:00.22 mysqld                                                                                                                                               

16839 mysql     20   0 1155m 188m  11m S  0.0  9.4   0:00.25 mysqld                                                                                                                                               

[root@LHRDB ~]# pstack 16833

Thread 29 (Thread 0x7f3654ed0700 (LWP 16834)):

#0  0x0000003790e33b57 in sigwaitinfo () from /lib64/libc.so.6

#1  0x0000000000f4d06b in timer_notify_thread_func ()

#2  0x0000000000fbdbf4 in pfs_spawn_thread ()

#3  0x00000037912079d1 in start_thread () from /lib64/libpthread.so.0

#4  0x0000003790ee8b6d in clone () from /lib64/libc.so.6

Thread 28 (Thread 0x7f3648bb7700 (LWP 16836)):

#0  0x0000003790a00614 in ?? () from /lib64/libaio.so.1

#1  0x00000000010ae1b4 in LinuxAIOHandler::collect() ()

#2  0x00000000010af8d4 in LinuxAIOHandler::poll(fil_node_t**, void**, IORequest*) ()

#3  0x00000000010b12fc in os_aio_handler(unsigned long, fil_node_t**, void**, IORequest*) ()

#4  0x000000000124618d in fil_aio_wait(unsigned long) ()

#5  0x0000000001153300 in io_handler_thread ()

#6  0x00000037912079d1 in start_thread () from /lib64/libpthread.so.0

#7  0x0000003790ee8b6d in clone () from /lib64/libc.so.6

。。。。。。。。。。省略。。。。。。。。。。。。

Thread 2 (Thread 0x7f364904a700 (LWP 19060)):

#0  0x0000003790edf343 in poll () from /lib64/libc.so.6

#1  0x00000000012b740f in vio_io_wait ()

#2  0x00000000012b7503 in vio_socket_io_wait ()

#3  0x00000000012b7b38 in vio_read ()

#4  0x0000000000c6b2e3 in net_read_raw_loop(st_net*, unsigned long) ()

#5  0x0000000000c6bb7b in net_read_packet(st_net*, unsigned long*) ()

#6  0x0000000000c6be2c in my_net_read ()

#7  0x0000000000c796bc in Protocol_classic::read_packet() ()

#8  0x0000000000c78432 in Protocol_classic::get_command(COM_DATA*, enum_server_command*) ()

#9  0x0000000000d1a227 in do_command(THD*) ()

#10 0x0000000000dea0fc in handle_connection ()

#11 0x0000000000fbdbf4 in pfs_spawn_thread ()

#12 0x00000037912079d1 in start_thread () from /lib64/libpthread.so.0

#13 0x0000003790ee8b6d in clone () from /lib64/libc.so.6

Thread 1 (Thread 0x7f365cca1720 (LWP 16833)):

#0  0x0000003790edf343 in poll () from /lib64/libc.so.6

#1  0x0000000000deb449 in Mysqld_socket_listener::listen_for_connection_event() ()

#2  0x00000000007c7bd2 in mysqld_main(int, char**) ()

#3  0x0000003790e1ed1d in __libc_start_main () from /lib64/libc.so.6

#4  0x00000000007bd739 in _start ()

通过“cat /proc/pid/status”可以查看某个进程的进程状态信息：

[root@LHRDB ~]# cat /proc/16833/status

Name:   mysqld

State:  S (sleeping)

Tgid:   16833

Pid:    16833

PPid:   16666

TracerPid:      0

Uid:    27      27      27      27

Gid:    27      27      27      27

Utrace: 0

FDSize: 256

Groups: 27

VmPeak:  1182708 kB

VmSize:  1182628 kB

VmLck:         0 kB

VmHWM:    192976 kB

VmRSS:    192976 kB

VmData:  1124900 kB

VmStk:        88 kB

VmExe:     23128 kB

VmLib:      4048 kB

VmPTE:       652 kB

VmSwap:        0 kB

Threads:        28

SigQ:   0/15826

SigPnd: 0000000000000000

ShdPnd: 0000000000000000

SigBlk: 0000000000084007

SigIgn: 0000000000003006

SigCgt: 00000001800006e8

CapInh: 0000000000000000

CapPrm: 0000000000000000

CapEff: 0000000000000000

CapBnd: ffffffffffffffff

Cpus_allowed:   ffffffff,ffffffff

Cpus_allowed_list:      0-63

Mems_allowed:   00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000001

Mems_allowed_list:      0

voluntary_ctxt_switches:        19

nonvoluntary_ctxt_switches:     111