pstack命令可显示每个进程的栈跟踪，pstack $pid即可，pstack命令须由$pid进程的属主或者root运行。

这次出现cpu占比100%的情况，但看memory占比，并无异常，怀疑是某个地方死循环了。经同事提醒，用pstack命令查看相关进程，通过运行多次pstack，发现代码栈总是停在同一个位置。具体看代码，发现就是这个地方写错了。

这真的是个很强大的命令！和strace命令一样强大

下面是有七个线程的进程的代码栈打印情况

pstack 4551

Thread 7 (Thread 1084229984 (LWP 4552)):

#0 0x000000302afc63dc in epoll_wait () from /lib64/tls/libc.so.6

#1 0x00000000006f0730 in ub::EPollEx::poll ()

#2 0x00000000006f172a in ub::NetReactor::callback ()

#3 0x00000000006fbbbb in ub::UBTask::CALLBACK ()

#4 0x000000302b80610a in start_thread () from /lib64/tls/libpthread.so.0

#5 0x000000302afc6003 in clone () from /lib64/tls/libc.so.6

#6 0x0000000000000000 in ?? ()

Thread 6 (Thread 1094719840 (LWP 4553)):

#0 0x000000302afc63dc in epoll_wait () from /lib64/tls/libc.so.6

#1 0x00000000006f0730 in ub::EPollEx::poll ()

#2 0x00000000006f172a in ub::NetReactor::callback ()

#3 0x00000000006fbbbb in ub::UBTask::CALLBACK ()

#4 0x000000302b80610a in start_thread () from /lib64/tls/libpthread.so.0

#5 0x000000302afc6003 in clone () from /lib64/tls/libc.so.6

#6 0x0000000000000000 in ?? ()

Thread 5 (Thread 1105209696 (LWP 4554)):

#0 0x000000302b80baa5 in __nanosleep_nocancel ()

#1 0x000000000079e758 in comcm::ms_sleep ()

#2 0x00000000006c8581 in ub::UbClientManager::healthyCheck ()

#3 0x00000000006c8471 in ub::UbClientManager::start_healthy_check ()

#4 0x000000302b80610a in start_thread () from /lib64/tls/libpthread.so.0

#5 0x000000302afc6003 in clone () from /lib64/tls/libc.so.6

#6 0x0000000000000000 in ?? ()

Thread 4 (Thread 1115699552 (LWP 4555)):

#0 0x000000302b80baa5 in __nanosleep_nocancel ()

#1 0x0000000000482b0e in armor::armor_check_thread ()

#2 0x000000302b80610a in start_thread () from /lib64/tls/libpthread.so.0

#3 0x000000302afc6003 in clone () from /lib64/tls/libc.so.6

#4 0x0000000000000000 in ?? ()

Thread 3 (Thread 1126189408 (LWP 4556)):

#0 0x000000302af8f1a5 in __nanosleep_nocancel () from /lib64/tls/libc.so.6

#1 0x000000302af8f010 in sleep () from /lib64/tls/libc.so.6

#2 0x000000000044c972 in Business_config_manager::run ()

#3 0x0000000000457b83 in Thread::run_thread ()

#4 0x000000302b80610a in start_thread () from /lib64/tls/libpthread.so.0

#5 0x000000302afc6003 in clone () from /lib64/tls/libc.so.6

#6 0x0000000000000000 in ?? ()

Thread 2 (Thread 1136679264 (LWP 4557)):

#0 0x000000302af8f1a5 in __nanosleep_nocancel () from /lib64/tls/libc.so.6

#1 0x000000302af8f010 in sleep () from /lib64/tls/libc.so.6

#2 0x00000000004524bb in Process_thread::sleep_period ()

#3 0x0000000000452641 in Process_thread::run ()

#4 0x0000000000457b83 in Thread::run_thread ()

#5 0x000000302b80610a in start_thread () from /lib64/tls/libpthread.so.0

#6 0x000000302afc6003 in clone () from /lib64/tls/libc.so.6

#7 0x0000000000000000 in ?? ()

Thread 1 (Thread 182894129792 (LWP 4551)):

#0 0x000000302af8f1a5 in __nanosleep_nocancel () from /lib64/tls/libc.so.6

#1 0x000000302af8f010 in sleep () from /lib64/tls/libc.so.6

#2 0x0000000000420d79 in Ad_preprocess::run ()

#3 0x0000000000450ad0 in main ()

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