TDengine Database產品提供服務端和客戶端兩個部分，其中服務端目前僅支持Linux環境，客戶端通過提供庫的方式，支持用戶在Linux環境或Windows環境運行。

TDengine Database服務或客戶端由于bug的存在，會出現crash的情況。當crash的時候，需要能生成core文件，支持更高效的分析原因，從而能快速的定位并解決bug。

Linux環境生成core的方法

在Linux環境中，生成core的兩個條件：

1、core file size不為0。

 該值缺省是0，表示不開啟core的生成，需要修改成不為0的值； 2、設置保存core文件的目錄有寫權限。

 缺省是在運行程序的當前目錄下，或systemctl啟動的程序則在“/”根目錄下。生成的core文件名為core，且多次發生crash時，只會保存最早一次core文件。

TDengine Database可以使用兩種方式來實現。

一、shell命令方式

1、設置不限制core file size

ulimit -c unlimited

2、設置生成core文件的目錄

sudo sysctl -w kernel.core_pattern='/<corefile_dir>/core-%e-%p'

其中 corefile_dir : 生成core后保存的路徑（需要提前建好）。%e 和 %p是在名稱中增加程序名和pid。這樣就可以保存多次core文件。

 缺點：這樣會將系統環境都修改了，用戶其他程序crash時，生成core文件也會保存到指定的路徑中！！！！

如果不修改kernel.core_pattern參數，只讓生成core文件名稱中增加pid，可以將 kernel.core_used_pid修改成1。

sudo sysctl kernel.core_uses_pid=1

注：啟動程序時的用戶權限，需要能有<corefile_dir>目錄的寫權限。

二、代碼API方式

可以使用系統提供的函數來完成上述參數的設置。

代碼示例如下：

  // 1. set ulimit -c unlimited
  struct rlimit rlim;
  struct rlimit rlim_new;
  if (getrlimit(RLIMIT_CORE, &rlim) == 0) {
    pPrint("the old unlimited para: rlim_cur=%d, rlim_max=%d", rlim.rlim_cur, rlim.rlim_max);
    rlim_new.rlim_cur = RLIM_INFINITY;
    rlim_new.rlim_max = RLIM_INFINITY;
    if (setrlimit(RLIMIT_CORE, &rlim_new) != 0) {
      pPrint("set unlimited fail, error: %s", strerror(errno));
      rlim_new.rlim_cur = rlim.rlim_max;
      rlim_new.rlim_max = rlim.rlim_max;
      (void)setrlimit(RLIMIT_CORE, &rlim_new);
    }
  }
  
  if (getrlimit(RLIMIT_CORE, &rlim) == 0) {
    pPrint("the new unlimited para: rlim_cur=%d, rlim_max=%d", rlim.rlim_cur, rlim.rlim_max);
  }

  // 2. set pid into core file name
  struct __sysctl_args args;
  int     old_usespid = 0;
  size_t  old_len     = 0;
  int     new_usespid = 1;
  size_t  new_len     = sizeof(new_usespid);  
  int name[] = {CTL_KERN, KERN_CORE_USES_PID};  
  memset(&args, 0, sizeof(struct __sysctl_args));
  args.name    = name;
  args.nlen    = sizeof(name)/sizeof(name[0]);
  args.oldval  = &old_usespid;
  args.oldlenp = &old_len;
  args.newval  = &new_usespid;
  args.newlen  = new_len;  
  old_len = sizeof(old_usespid);  
  if (syscall(SYS__sysctl, &args) == -1) {
      pPrint("_sysctl(kern_core_uses_pid) set fail: %s", strerror(errno));
  }  
  pPrint("The old core_uses_pid[%d]: %d", old_len, old_usespid);
  old_usespid = 0;
  old_len     = 0;
  memset(&args, 0, sizeof(struct __sysctl_args));
  args.name    = name;
  args.nlen    = sizeof(name)/sizeof(name[0]);
  args.oldval  = &old_usespid;
  args.oldlenp = &old_len;  
  old_len = sizeof(old_usespid);  
  if (syscall(SYS__sysctl, &args) == -1) {
      pPrint("_sysctl(kern_core_uses_pid) get fail: %s", strerror(errno));
  }  
  pPrint("The new core_uses_pid[%d]: %d", old_len, old_usespid);

設置kernal.core_pattern的函數示例：

  // 3. create the path for saving core file
  int status; 
  char coredump_dir[32] = "/var/log/taosdump";
  if (opendir(coredump_dir) == NULL) {
    status = mkdir(coredump_dir, S_IRWXU | S_IRWXG | S_IRWXO); 
    if (status) {
      pPrint("mkdir fail, error: %s\n", strerror(errno));
    }
  }

  // 4. set kernel.core_pattern
   struct __sysctl_args args;
   char    old_corefile[128];
   size_t  old_len;
   char    new_corefile[128] = "/var/log/taosdump/core-%e-%p";
   size_t  new_len = sizeof(new_corefile);   
   int name[] = {CTL_KERN, KERN_CORE_PATTERN};
   memset(&args, 0, sizeof(struct __sysctl_args));
   args.name    = name;
   args.nlen    = sizeof(name)/sizeof(name[0]);
   args.oldval  = old_corefile;
   args.oldlenp = &old_len;
   args.newval  = new_corefile;
   args.newlen  = new_len;
   old_len = sizeof(old_corefile);
   if (syscall(SYS__sysctl, &args) == -1) {
       pPrint("_sysctl(kern_core_pattern) set fail: %s", strerror(errno));
   }   
   pPrint("The old kern_core_pattern: %*s\n", old_len, old_corefile);
   memset(&args, 0, sizeof(struct __sysctl_args));
   args.name    = name;
   args.nlen    = sizeof(name)/sizeof(name[0]);
   args.oldval  = old_corefile;
   args.oldlenp = &old_len;   
   old_len = sizeof(old_corefile);
   if (syscall(SYS__sysctl, &args) == -1) {
       pPrint("_sysctl(kern_core_pattern) get fail: %s", strerror(errno));
   }   
   pPrint("The new kern_core_pattern: %*s\n", old_len, old_corefile);

 當在linux環境出現crash時，獲得core文件以及對應的應用程序，然后使用gdb進行分析，示例如下：

plum@plum-VirtualBox:~/git/TDinternal/debug/build/bin$ sudo gdb ./taos core-taos-22675
GNU gdb (Ubuntu 7.11.1-0ubuntu1~16.5) 7.11.1
Copyright (C) 2016 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <//gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.  Type "show copying"
and "show warranty" for details.
This GDB was configured as "x86_64-linux-gnu".
Type "show configuration" for configuration details.
For bug reporting instructions, please see:
<//www.gnu.org/software/gdb/bugs/>.
Find the GDB manual and other documentation resources online at:
<//www.gnu.org/software/gdb/documentation/>.
For help, type "help".
Type "apropos word" to search for commands related to "word"...
Reading symbols from ./taos...done.
Core was generated by `/home/plum/git/TDengine/debug/build/bin/taos -c /etc/taos'.
(gdb) bt
#0  0x00000000004261d4 in tsParseOneRowData (str=0x980, pDataBlocks=0x7fffd8033ca0, schema=0x7fffd8034884, spd=0x7fffedcd2660, error=0x79fbf0 "", timePrec=0)
    at /home/plum/git/TDinternal/community/src/client/src/tscParseInsert.c:411
#1  0x00000000004266f8 in tsParseValues (str=0x7fffedcd23b0, pDataBlock=0x7fffd8033ca0, pMeterMeta=0x7fffd803483c, maxRows=14, spd=0x7fffedcd2660, error=0x79fbf0 "")
    at /home/plum/git/TDinternal/community/src/client/src/tscParseInsert.c:508
#2  0x0000000000426d8b in doParseInsertStatement (pSql=0x797dd0, pTableHashList=0x7fffd80342e0, str=0x7fffedcd23b0, spd=0x7fffedcd2660, totalNum=0x7fffedcd23cc)
    at /home/plum/git/TDinternal/community/src/client/src/tscParseInsert.c:640
#3  0x00000000004281da in doParserInsertSql (pSql=0x797dd0, str=0x7fffd8034c64 "0, '123', '11111\\'9911111');") at /home/plum/git/TDinternal/community/src/client/src/tscParseInsert.c:1036
#4  0x00000000004284b9 in tsParseInsertSql (pSql=0x797dd0, sql=0x7fffd8034c30 "insert into test.demo (ts, task_id, message) values(0, '123', '11111\\'9911111');", acct=0x7074a2 "0", db=0x7074c2 "0.test")
    at /home/plum/git/TDinternal/community/src/client/src/tscParseInsert.c:1103
#5  0x00000000004285f2 in tsParseSql (pSql=0x797dd0, acct=0x7074a2 "0", db=0x7074c2 "0.test", multiVnodeInsertion=false) at /home/plum/git/TDinternal/community/src/client/src/tscParseInsert.c:1127
#6  0x0000000000455572 in taos_query_imp (pObj=0x707450, pSql=0x797dd0) at /home/plum/git/TDinternal/community/src/client/src/tscSql.c:235
#7  0x0000000000455907 in taos_query (taos=0x707450, sqlstr=0x7fffd80008c0 "insert into test.demo (ts, task_id, message) values(0, '123', '11111\\'9911111');")
    at /home/plum/git/TDinternal/community/src/client/src/tscSql.c:293
#8  0x0000000000414b01 in shellRunCommandOnServer (con=0x707450, command=0x7fffd80008c0 "insert into test.demo (ts, task_id, message) values(0, '123', '11111\\'9911111');")
    at /home/plum/git/TDinternal/community/src/kit/shell/src/shellEngine.c:253
#9  0x00000000004149ad in shellRunCommand (con=0x707450, command=0x7fffd80008c0 "insert into test.demo (ts, task_id, message) values(0, '123', '11111\\'9911111');")
    at /home/plum/git/TDinternal/community/src/kit/shell/src/shellEngine.c:215
#10 0x0000000000417b75 in shellLoopQuery (arg=0x707450) at /home/plum/git/TDinternal/community/src/kit/shell/src/shellLinux.c:291
#11 0x00007ffff7bc16ba in start_thread (arg=0x7fffedcd4700) at pthread_create.c:333
#12 0x00007ffff73e641d in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:109

windows環境生成core的方法

一、設置生成dmp文件方式

通過改注冊表的設置讓操作系統在程序crash的時候自動生成dump，并放到特定的目錄下

增加注冊表HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\Windows Error Reporting\LocalDumps

添加項如下圖：

其中DumpType代表的含義是：0 = Create a custom dump ，1 = Mini dump ，2 = Full dump

程序崩潰后，就會在c:\TDengine目錄下生成dump文件。

二、使用VS調試dmp文件

 用VS打開dmp文件。測試時dmp文件時本地產生的，因此VS會依據dmp文件自行找到exe，pdb和源代碼的路徑。因此直接點擊調試，程序會出錯代碼行中斷。

但若dump文件是exe在另一臺機器上產生的，則我們最好把exe,pdb,dmp放到同一文件夾下，必須保證pdb與出問題的exe是同一時間生成的，用VS打開dump文件后還需要設置符號表文件路徑和源代碼路徑：

（1） 當把pdb文件與dmp文件放入同一目錄下時，就不需設置其路徑，否則需要設置

工具->選項->調試->符號：

2）還需設置源代碼路徑：

屬性->調試源代碼：

這樣點擊“使用僅限本機進行調試”，即可在出錯代碼行中斷：