linux – 为什么PMP(穷人的探查器)不能在nginx上运行？

概述有一个非常有用的gdb“脚本”叫做 poor man’s profiler.它调用这个命令： gdb -ex "set pagination 0" -ex "thread apply all bt" --batch -p $pid 它适用于大多数Linux进程,但不适用于nginx Web服务器. 正常输出： # gdb -ex "set pagination 0" -ex "thread app 有一个非常有用的gdb“脚本”叫做 poor man’s profiler.它调用这个命令：

gdb -ex "set pagination 0" -ex "thread apply all bt" --batch -p $pID

它适用于大多数linux进程,但不适用于nginx Web服务器.

正常输出：

# gdb -ex "set pagination 0" -ex "thread apply all bt" -batch -p 5286Using host libthread_db library "/lib/libthread_db.so.1".[Thread deBUGging using libthread_db enabled][New Thread 0xb7d996c0 (LWP 5286)][New Thread 0xb588ab90 (LWP 5292)][New Thread 0xb608bb90 (LWP 5291)][New Thread 0xb688cb90 (LWP 5290)][New Thread 0xb708db90 (LWP 5289)][New Thread 0xb788eb90 (LWP 5288)]0xffffe410 in __kernel_vsyscall ()Thread 6 (Thread 0xb788eb90 (LWP 5288)):#0  0xffffe410 in __kernel_vsyscall ()#1  0xb7e5d7a6 in epoll_wait () from /lib/libc.so.6#2  0xb7ef4f3b in epoll_dispatch () from /usr/lib/libevent-1.3b.so.1#3  0xb7ee963a in event_base_loop () from /usr/lib/libevent-1.3b.so.1#4  0x08055537 in worker_libevent (arg=0x805f3a0) at thread.c:245#5  0xb7ed2192 in start_thread () from /lib/libpthread.so.0#6  0xb7e5d02e in clone () from /lib/libc.so.6[cut]Thread 1 (Thread 0xb7d996c0 (LWP 5286)):#0  0xffffe410 in __kernel_vsyscall ()#1  0xb7e5d7a6 in epoll_wait () from /lib/libc.so.6#2  0xb7ef4f3b in epoll_dispatch () from /usr/lib/libevent-1.3b.so.1#3  0xb7ee963a in event_base_loop () from /usr/lib/libevent-1.3b.so.1#4  0x0804f439 in main (argc=1,argv=0xbfbaff14) at memcached.c:4681#0  0xffffe410 in __kernel_vsyscall ()

Nginx输出：

# gdb -ex "set pagination 0" -ex "thread apply all bt" -batch -p 6120Using host libthread_db library "/lib/libthread_db.so.1".0xffffe410 in __kernel_vsyscall ()

但是如果使用“bt”而不是“thread apply all bt”,它的效果很好：

# gdb -ex "set pagination 0" -ex "bt" -batch -p 6120Using host libthread_db library "/lib/libthread_db.so.1".0xffffe410 in __kernel_vsyscall ()#0  0xffffe410 in __kernel_vsyscall ()#1  0xb7c83778 in epoll_wait () from /lib/libc.so.6#2  0x080664c0 in ngx_epoll_process_events (cycle=0x80d14b8,timer=500,flags=1) at src/event/modules/ngx_epoll_module.c:530#3  0x0805f73b in ngx_process_events_and_timers (cycle=0x80d14b8) at src/event/ngx_event.c:245#4  0x080652b3 in ngx_worker_process_cycle (cycle=0x80d14b8,data=0x0) at src/os/unix/ngx_process_cycle.c:795#5  0x08063ba1 in ngx_spawn_process (cycle=0x80d14b8,proc=0x80651fb <ngx_worker_process_cycle>,data=0x0,name=0x80a881d "worker process",respawn=-3) at src/os/unix/ngx_process.c:196#6  0x080648d2 in ngx_start_worker_processes (cycle=0x80d14b8,n=8,type=-3) at src/os/unix/ngx_process_cycle.c:355#7  0x0806581f in ngx_master_process_cycle (cycle=0xfffffffc) at src/os/unix/ngx_process_cycle.c:136#8  0x0804d076 in main (argc=1,argv=0xbfd86544) at src/core/Nginx.c:396

这是为什么？据我所知,“线程应用所有bt”必须工作,即使进程中只有一个执行线程.

更新：

手动gdb连接并发出“info threads”命令.

# gdb -p 17461GNU gdb 6.4copyright 2005 Free Software Foundation,Inc.GDB is free software,covered by the GNU General Public license,and you arewelcome to change it and/or distribute copIEs of it under certain conditions.Type "show copying" to see the conditions.There is absolutely no warranty for GDB.  Type "show warranty" for details.This GDB was configured as "i586-suse-linux".Attaching to process 17461Reading symbols from /export/depo/apache/linux/Nginx-0.8.34/sbin/Nginx...done.Using host libthread_db library "/lib/libthread_db.so.1".Reading symbols from /lib/libcrypt.so.1...done.Loaded symbols for /lib/libcrypt.so.1Reading symbols from /export/depo/MysqL/linux/MysqL-proxy-0.7.2/lib/libpcre.so.0...done.Loaded symbols for /opt/gnu/MysqL-proxy/lib/libpcre.so.0Reading symbols from /usr/lib/libssl.so.0.9.8...done.Loaded symbols for /usr/lib/libssl.so.0.9.8Reading symbols from /usr/lib/libcrypto.so.0.9.8...done.Loaded symbols for /usr/lib/libcrypto.so.0.9.8Reading symbols from /lib/libdl.so.2...done.Loaded symbols for /lib/libdl.so.2Reading symbols from /lib/libz.so.1...done.Loaded symbols for /lib/libz.so.1Reading symbols from /lib/libc.so.6...done.Loaded symbols for /lib/libc.so.6Reading symbols from /lib/ld-linux.so.2...done.Loaded symbols for /lib/ld-linux.so.20xffffe410 in __kernel_vsyscall ()(gdb) info threads(gdb) thread 0Thread ID 0 not kNown.(gdb) bt#0  0xffffe410 in __kernel_vsyscall ()#1  0xb7d0dd98 in __epoll_wait_nocancel () from /lib/libc.so.6#2  0x08066e7d in ngx_epoll_process_events (cycle=0x816b708,flags=1) at src/event/modules/ngx_epoll_module.c:530#3  0x0805f4a2 in ngx_process_events_and_timers (cycle=0x816b708) at src/event/ngx_event.c:245#4  0x08064d83 in ngx_worker_process_cycle (cycle=0x816b708,data=0x0) at src/os/unix/ngx_process_cycle.c:795#5  0x08063661 in ngx_spawn_process (cycle=0x816b708,proc=0x8064ccb <ngx_worker_process_cycle>,name=0x80a42ed "worker process",respawn=-4) at src/os/unix/ngx_process.c:196#6  0x080643a1 in ngx_start_worker_processes (cycle=0x816b708,type=-4) at src/os/unix/ngx_process_cycle.c:355#7  0x0806595c in ngx_master_process_cycle (cycle=0x816b708) at src/os/unix/ngx_process_cycle.c:249#8  0x0804cf7f in main (argc=1,argv=0xbfdb1874) at src/core/Nginx.c:396

解决方法 该线程为每个线程应用所有bt做(惊讶！)bt.一旦有任何线程导致错误(但不应该发生),它也会停止.

因此,如果您手动附加到Nginx,然后执行信息线程,然后继续重复线程N和bt,您可能会找到GDB无法产生回溯的线程.

确切地知道GDB为该线程打印的内容可能很有趣.

您可能还想重试当前版本的GDB(7.2)

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