用法GDB调试PHP代码解决PHP代码死循环问题_

1、用法GDB调试PHP代码，解决PHP代码死循环问题_ 最近在帮同事解决Swoole Server问题时，发觉有1个worker进程始终处于R的状态，而且CPU耗时特别高。初步断定是PHP代码中发生死循环。 下面通过一段代码展现如何解决PHP死循环问题。 代码如下: #dead_loop.php $array = array(); for($i = 0; $i 10000; $i+) $array = $i; include _DIR_./include.php; #include.php while(1) usleep(10); $keys = array_flip($array); $ind

2、ex = array_search(rand(1500, 9999), $array); $str = str_repeat(A, $index); $strb = test($index, $str); function test($index, $str) return str_replace(A, B, $str); 通过ps aux得到进程ID和状态如下，用法gdb -p 进程ptrace跟踪，通过bt指令得到调用栈 代码如下: htf 3834 2.6 0.2 166676 22060 pts/12 R+ 10:50 0:12 php dead_loop.php gdb -p 383

3、4 (gdb) bt #0 0x00000000008cc03f in zend_mm_check_ptr (heap=0x1eaa2c0, ptr=0x2584910, silent=1, _zend_filename=0xee3d40 /home/htf/workspace/php-5.4.27/Zend/zend_variables.c, _zend_lineno=182, _zend_orig_filename=0xee1888 /home/htf/workspace/php-5.4.27/Zend/zend_execute_API.c, _zend_orig_lineno=437)

4、at /home/htf/workspace/php-5.4.27/Zend/zend_alloc.c:1485 #1 0x00000000008cd643 in _zend_mm_free_int (heap=0x1eaa2c0, p=0x2584910, _zend_filename=0xee3d40 /home/htf/workspace/php-5.4.27/Zend/zend_variables.c, _zend_lineno=182, _zend_orig_filename=0xee1888 /home/htf/workspace/php-5.4.27/Zend/zend_exec

5、ute_API.c, _zend_orig_lineno=437) at /home/htf/workspace/php-5.4.27/Zend/zend_alloc.c:2064 #2 0x00000000008cebf7 in _efree (ptr=0x2584910, _zend_filename=0xee3d40 /home/htf/workspace/php-5.4.27/Zend/zend_variables.c, _zend_lineno=182, _zend_orig_filename=0xee1888 /home/htf/workspace/php-5.4.27/Zend/

6、zend_execute_API.c, _zend_orig_lineno=437) at /home/htf/workspace/php-5.4.27/Zend/zend_alloc.c:2436 #3 0x00000000008eda0a in _zval_ptr_dtor (zval_ptr=0x25849a0, _zend_filename=0xee3d40 /home/htf/workspace/php-5.4.27/Zend/zend_variables.c, _zend_lineno=182) at /home/htf/workspace/php-5.4.27/Zend/zend

7、_execute_API.c:437 #4 0x00000000008fe687 in _zval_ptr_dtor_wrapper (zval_ptr=0x25849a0) at /home/htf/workspace/php-5.4.27/Zend/zend_variables.c:182 #5 0x000000000091259f in zend_hash_destroy (ht=0x7f7263f6e380) at /home/htf/workspace/php-5.4.27/Zend/zend_hash.c:560 #6 0x00000000008fe2c5 in _zval_dto

8、r_func (zvalue=0x7f726426fe50, _zend_filename=0xeea290 /home/htf/workspace/php-5.4.27/Zend/zend_execute.c, _zend_lineno=901) at /home/htf/workspace/php-5.4.27/Zend/zend_variables.c:45 #7 0x0000000000936656 in _zval_dtor (zvalue=0x7f726426fe50, _zend_filename=0xeea290 /home/htf/workspace/php-5.4.27/Z

9、end/zend_execute.c, _zend_lineno=901) at /home/htf/workspace/php-5.4.27/Zend/zend_variables.h:35 #8 0x0000000000939747 in zend_assign_to_variable (variable_ptr_ptr=0x7f7263f8e738, value=0x7f726426f6a8) at /home/htf/workspace/php-5.4.27/Zend/zend_execute.c:901 #9 0x0000000000997ee5 in ZEND_ASSIGN_SPE

10、C_CV_VAR_HANDLER (execute_data=0x7f726d04b2a8) at /home/htf/workspace/php-5.4.27/Zend/zend_vm_execute.h:33168 #10 0x000000000093b5fd in execute (op_array=0x21d58b0) at /home/htf/workspace/php-5.4.27/Zend/zend_vm_execute.h:410 #11 0x0000000000901692 in zend_execute_scripts (type=8, retval=0x0, file_c

11、ount=3) at /home/htf/workspace/php-5.4.27/Zend/zend.c:1315 #12 0x000000000087926a in php_execute_script (primary_file=0x7ffffe0038d0) at /home/htf/workspace/php-5.4.27/main/main.c:2502 #13 0x00000000009a32e3 in do_cli (argc=2, argv=0x7ffffe004d18) at /home/htf/workspace/php-5.4.27/sapi/cli/php_cli.c

12、:989 #14 0x00000000009a4491 in main (argc=2, argv=0x7ffffe004d18) at /home/htf/workspace/php-5.4.27/sapi/cli/php_cli.c:1365 执行gdb后，死循环的进程会变成T的状态，表示正在Trace。这个是独占的，所以不能再用法strace/gdb或者其他ptrace工具对此进程进行调试。另外此进程会中断执行。gdb输入c后，程序连续向下运行。然后再次按下ctrl + c中断程序。 通过bt指令查看进程的调用栈。 代码如下: (gdb) bt #0 _zend_mm_alloc_int

13、 (heap=0x1eaa2c0, size=72, _zend_filename=0xe43410 /home/htf/workspace/php-5.4.27/ext/standard/array.c, _zend_lineno=2719, _zend_orig_filename=0xee5a38 /home/htf/workspace/php-5.4.27/Zend/zend_hash.c, _zend_orig_lineno=412) at /home/htf/workspace/php-5.4.27/Zend/zend_alloc.c:1895 #1 0x00000000008ceb

14、86 in _emalloc (size=72, _zend_filename=0xe43410 /home/htf/workspace/php-5.4.27/ext/standard/array.c, _zend_lineno=2719, _zend_orig_filename=0xee5a38 /home/htf/workspace/php-5.4.27/Zend/zend_hash.c, _zend_orig_lineno=412) at /home/htf/workspace/php-5.4.27/Zend/zend_alloc.c:2425 #2 0x0000000000911d85

15、 in _zend_hash_index_update_or_next_insert (ht=0x2257a10, h=3972, pData=0x7ffffe0012b0, nDataSize=8, pDest=0x0, flag=1, _zend_filename=0xe43410 /home/htf/workspace/php-5.4.27/ext/standard/array.c, _zend_lineno=2719) at /home/htf/workspace/php-5.4.27/Zend/zend_hash.c:412 #3 0x00000000007767e1 in zif_

16、array_flip (ht=1, return_value=0x7f726424ea68, return_value_ptr=0x0, this_ptr=0x0, return_value_used=1) at /home/htf/workspace/php-5.4.27/ext/standard/array.c:2719 #4 0x000000000093c03e in zend_do_fcall_common_helper_SPEC (execute_data=0x7f726d04b2a8) at /home/htf/workspace/php-5.4.27/Zend/zend_vm_e

17、xecute.h:643 #5 0x00000000009400e6 in ZEND_DO_FCALL_SPEC_CONST_HANDLER (execute_data=0x7f726d04b2a8) at /home/htf/workspace/php-5.4.27/Zend/zend_vm_execute.h:2233 #6 0x000000000093b5fd in execute (op_array=0x21d58b0) at /home/htf/workspace/php-5.4.27/Zend/zend_vm_execute.h:410 两次的BT信息不一样，这是由于程序在不同的位

18、置中断。看到execute (oparray=0x21d58b0) 这一行，这里就是PHP执行oparray的入口了。gdb下输入f 6，(通过调用栈编号可得)。 代码如下: (gdb) f 6 #6 0x000000000093b5fd in execute (op_array=0x21d58b0) at /home/htf/workspace/php-5.4.27/Zend/zend_vm_execute.h:410 410 if (ret = OPLINE-handler(execute_data TSRMLS_CC) 0) (gdb) p *op_array $2 = type = 2

19、 002, function_name = 0x7f726d086540 test, scope = 0x0, fn_flags = 134217728, prototype = 0x0, num_args = 2, required_num_args = 2, arg_info = 0x7f726d086bd8, refcount = 0x7f726d0870f0, opcodes = 0x7f726424d600, last = 8, vars = 0x7f726424e890, last_var = 2, T = 1, brk_cont_array = 0x0, last_brk_con

20、t = 0, try_catch_array = 0x0, last_try_catch = 0, static_variables = 0x0, this_var = 4294967295, filename = 0x7f726424ba38 /home/htf/root/include.php, line_start = 12, line_end = 15, doc_comment = 0x0, doc_comment_len = 0, early_binding = 4294967295, literals = 0x7f726424eae0, last_literal = 4, run_time_cache = 0x7f726450bfb0, last_cache_slot = 1, reserved = 0x0, 0x0, 0x0, 0x0 这里的filename就能看到op_array是哪个PHP文件的。然后输入f 0进入当前位置。 代码如下: (gdb) p *executor_globals.opline_ptr $4 = handler = 0x93ff9c , op1 = constant = 1680133296, var = 1680133296, num = 1680133296, hash = 1401