跟踪系统调用
当想知道一个进程在做什么事情的时候，可以通过strace命令跟踪一个进程的所有系统调用。
1、运行 php start.php status 能看到workerman相关进程的信息 如下：
Hello admin
---------------------------------------GLOBAL STATUS--------------------------------------------
Workerman version:3.0.1
start time:2014-08-12 17:42:04 run 0 days 1 hours
load average: 3.34, 3.59, 3.67
1 users 8 workers 14 processes
worker_name exit_status exit_count
BusinessWorker 0 0
ChatWeb 0 0
FileMonitor 0 0
Gateway 0 0
Monitor 0 0
StatisticProvider 0 0
StatisticWeb 0 0
StatisticWorker 0 0
---------------------------------------PROCESS STATUS-------------------------------------------
pid memory listening timestamp worker_name total_request packet_err thunder_herd client_close send_fail throw_exception suc/total
10352 1.5M tcp://0.0.0.0:55151 1407836524 ChatWeb 12 0 0 2 0 0 100%
10354 1.25M tcp://0.0.0.0:7272 1407836524 Gateway 3 0 0 0 0 0 100%
10355 1.25M tcp://0.0.0.0:7272 1407836524 Gateway 0 0 1 0 0 0 100%
10365 1.25M tcp://0.0.0.0:55757 1407836524 StatisticWeb 0 0 0 0 0 0 100%
10358 1.25M tcp://0.0.0.0:7272 1407836524 Gateway 3 0 2 0 0 0 100%
10364 1.25M tcp://0.0.0.0:55858 1407836524 StatisticProvider 0 0 0 0 0 0 100%
10356 1.25M tcp://0.0.0.0:7272 1407836524 Gateway 3 0 2 0 0 0 100%
10366 1.25M udp://0.0.0.0:55656 1407836524 StatisticWorker 55 0 0 0 0 0 100%
10349 1.25M tcp://127.0.0.1:7373 1407836524 BusinessWorker 5 0 0 0 0 0 100%
10350 1.25M tcp://127.0.0.1:7373 1407836524 BusinessWorker 0 0 0 0 0 0 100%
10351 1.5M tcp://127.0.0.1:7373 1407836524 BusinessWorker 5 0 0 0 0 0 100%
10348 1.25M tcp://127.0.0.1:7373 1407836524 BusinessWorker 2 0 0 0 0 0 100%2、例如我们想知道pid为10354的gateway进程在做什么，则可以运行命令 strace -p 10354 (可能需要root权限) 类似如下：
sudo strace -p 10354
Process 10354 attached - interrupt to quit
clock_gettime(CLOCK_MONOTONIC, {118627, 242986712}) = 0
gettimeofday({1407840609, 102439}, NULL) = 0
epoll_wait(3, 985f4f0, 32, -1) = -1 EINTR (Interrupted system call)
--- SIGUSR2 (User defined signal 2) @ 0 (0) ---
send(7, "\f", 1, 0) = 1
sigreturn() = ? (mask now [])
clock_gettime(CLOCK_MONOTONIC, {118627, 699623319}) = 0
gettimeofday({1407840609, 559092}, NULL) = 0
epoll_wait(3, {{EPOLLIN, {u32=9, u64=9}}}, 32, -1) = 1
clock_gettime(CLOCK_MONOTONIC, {118627, 699810499}) = 0
gettimeofday({1407840609, 559277}, NULL) = 0
recv(9, "\f", 1024, 0) = 1
recv(9, 0xb60b4880, 1024, 0) = -1 EAGAIN (Resource temporarily unavailable)
epoll_wait(3, 985f4f0, 32, -1) = -1 EINTR (Interrupted system call)
--- SIGUSR2 (User defined signal 2) @ 0 (0) ---
send(7, "\f", 1, 0) = 1
sigreturn() = ? (mask now [])
clock_gettime(CLOCK_MONOTONIC, {118628, 699497204}) = 0
gettimeofday({1407840610, 558937}, NULL) = 0
epoll_wait(3, {{EPOLLIN, {u32=9, u64=9}}}, 32, -1) = 1
clock_gettime(CLOCK_MONOTONIC, {118628, 699588603}) = 0
gettimeofday({1407840610, 559023}, NULL) = 0
recv(9, "\f", 1024, 0) = 1
recv(9, 0xb60b4880, 1024, 0) = -1 EAGAIN (Resource temporarily unavailable)
epoll_wait(3, 985f4f0, 32, -1) = -1 EINTR (Interrupted system call)
--- SIGUSR2 (User defined signal 2) @ 0 (0) ---
send(7, "\f", 1, 0) = 1
sigreturn() = ? (mask now [])3、其中每一行是一个系统调用，从这个信息中我们很容易看到进程在做一些什么事情，可以定位到进程卡在哪里，卡在连接还是读取网络数据等
