问题描述
我在Linux平台上构建一个C应用程序。我需要使用libmysqlclient接口到数据库。
我下载了Linux源代码包mysql-connector-c-6.0.2.tar.gz。我按照说明编译它。我得到以下库：
libmysqlclient.a libmysqlclient.so libmysql.so.16
libmysqlclient_r.so libmysql。所以libmysql.so.16.0.0
如果我的应用程序是多线程的，用libmysqlclient.a？根据mysql文档（），与
在使用libmysqlclient.a链接我的应用程序后，我在应用程序中遇到调用栈下面的崩溃：
＃0 0x0867878a在my_stat（）
无符号表信息可用。
＃1 0x08671611在init_available_charsets.clone.0（）
无符号表信息可用。
＃2 0x086720d5在get_charset_by_csname（）
没有符号表信息可用。
＃3 0x086522af在mysql_init_character_set（）
没有符号表信息可用。
＃4 0x0865266d在mysql_real_connect（）
在我的应用程序中，线程函数：
if（NULL ==（pMySQL = mysql_init（NULL）））
{
return -1;
}
if（NULL == mysql_real_connect（pMySQL，ServerName，UserName，Password，Name，Port，NULL，0））
{
mysql_close（pMySQL） ;
return -1;
}
if（0！= mysql_query（pMySQL，pQuery））
{
mysql_close（pMySQL）;
return -1;
}
mysql_close（pMySQL）;
我不使用libmysqlclient_r.so，因为我想链接到mysql客户端库静态。有什么方法可以用cmake生成libmysqlclient_r.a？
更新：
不做任何其他事情，我只是改变mysql客户端生成类型为调试。现在我在mysql_init（）函数中崩溃。
在应用程序控制台上，我得到以下print：
safe_mutex：尝试在/install/mysqlconnc/mysql-connector-c-6.0.2/mysys/safemalloc.c，第520行锁定单位化mutex
崩溃的调用堆栈如下：
＃0 0x00556430在__kernel_vsyscall（）
无符号表信息可用。
＃1 0x45fdf2f1在raise（）中从/lib/libc.so.6
无符号表信息可用。
＃2 0x45fe0d5e在abort（）中从/lib/libc.so.6
无符号表信息可用。
＃3 0x086833e5 in safe_mutex_lock（mp = 0x915e8e0，my_flags = 0，
file = 0x895b9d8/install/mysqlconnc/mysql-connector-c-6.0.2/mysys/safemalloc.c，line = 520）
at /install/mysqlconnc/mysql-connector-c-6.0.2/mysys/thr_mutex.c:178
错误= 140915306
__PRETTY_FUNCTION__ =safe_mutex_lock
＃ 4 0x08682715 in _sanity（
filename = 0x895a87c/install/mysqlconnc/mysql-connector-c-6.0.2/mysys/my_error.c，lineno = 195）
在/ install / mysqlconnc / mysql -connector-c-6.0.2 / mysys / safemalloc.c：520
irem = 0xf2300468
flag = 0
count = 0
＃5 0x0868186b in _mymalloc ，
filename = 0x895a87c/install/mysqlconnc/mysql-connector-c-6.0.2/mysys/my_error.c，lineno = 195，MyFlags = 16）
在/ install / mysqlconnc / mysql -connector-c-6.0.2 / mysys / safemalloc.c：130
irem = 0x0
data = 0x0
_db_stack_frame_ = {func = 0x6d617266< Address 0x6d617266 out of bounds> file = 0x65685f65<地址0x65685f65超出范围>，
level = 0，prev = 0x0}
在my_error_register中为6 0x0867e0e1（errmsgs = 0x89a7760，first = 2000，last = 2058）
at /install/mysqlconnc/mysql-connector-c-6.0.2/mysys/my_error.c:194
meh_p = 0x46087568
search_meh_pp = 0x1000
＃7 0x08655f7e in init_client_errs（）
at /install/mysqlconnc/mysql-connector-c-6.0.2/libmysql/errmsg.c:238
没有本地。
＃8 0x08655fe3在mysql_server_init（argc = 0，argv = 0x0，groups = 0x0）
at /install/mysqlconnc/mysql-connector-c-6.0.2/libmysql/libmysql.c:128
result = 0
＃9 0x08651fc0在mysql_init（mysql = 0x0）
at /install/mysqlconnc/mysql-connector-c-6.0.2/libmysql/client.c:1606
解决方案：
我在创建线程之前调用mysql_library_init（），并在线程终止后调用mysql_library_end（）。在每个线程中，我在线程函数的开始调用mysql_thread_init（），并在线程函数的结尾调用mysql_thread_end（）。
解决方案更新：
您似乎需要致电
mysql_init（）：关于您的原始问题，
libmysqlclient_r.so实际上是libmysql.so的符号链接。您可以更改libmysql / CMakeLists.txt以生成静态库（libmysql.a）， c $ c> SHARED 关键字：ADD_LIBRARY（libmysql SHARED $ {CLIENT_SOURCES}但是，我建议（1）尝试运行相同的代码，而不使用线程（1）尝试运行相同的代码，而不使用线程并查看问题是否仍然存在，（2）构建和使用调试版本的库：cmake -GUnix Makefiles -DCMAKE_BUILD_TYPE = Debug
make
这样可以更详细地调查问题。
I am building a C application on Linux platform. I need to use libmysqlclient for interfacing to database.
I downloaded Linux source code package mysql-connector-c-6.0.2.tar.gz. I compiled it as per the instructions. I get the below libraries:
libmysqlclient.a libmysqlclient.so libmysql.so.16 libmysqlclient_r.so libmysql.so libmysql.so.16.0.0If my application is multi-threaded, can I link my application with libmysqlclient.a? As per mysql documentation (http://forge.mysql.com/wiki/Autotools_to_CMake_Transition_Guide), with cmake tool, clients are always thread safe.
After linking my application with libmysqlclient.a, I get a crash in my application with below call stack:
#0 0x0867878a in my_stat () No symbol table info available. #1 0x08671611 in init_available_charsets.clone.0 () No symbol table info available. #2 0x086720d5 in get_charset_by_csname () No symbol table info available. #3 0x086522af in mysql_init_character_set () No symbol table info available. #4 0x0865266d in mysql_real_connect ()In my application, I have below code in the thread function:
if (NULL == (pMySQL = mysql_init(NULL))) { return -1; } if (NULL == mysql_real_connect(pMySQL, ServerName, UserName, Password, Name, Port, NULL, 0)) { mysql_close(pMySQL); return -1; } if (0 != mysql_query(pMySQL, pQuery)) { mysql_close(pMySQL); return -1; } mysql_close(pMySQL);I am not using libmysqlclient_r.so as I want to link to mysql client library statically. Is there any way to generate libmysqlclient_r.a with cmake?
Update:
Without doing anything else, I just changed mysql client build type to debug. Now I get the crash in mysql_init() function.
On the application console, I get below print:
safe_mutex: Trying to lock unitialized mutex at /install/mysqlconnc/mysql-connector-c-6.0.2/mysys/safemalloc.c, line 520The call stack of the crash is as below:
#0 0x00556430 in __kernel_vsyscall () No symbol table info available. #1 0x45fdf2f1 in raise () from /lib/libc.so.6 No symbol table info available. #2 0x45fe0d5e in abort () from /lib/libc.so.6 No symbol table info available. #3 0x086833e5 in safe_mutex_lock (mp=0x915e8e0, my_flags=0, file=0x895b9d8 "/install/mysqlconnc/mysql-connector-c-6.0.2/mysys/safemalloc.c", line=520) at /install/mysqlconnc/mysql-connector-c-6.0.2/mysys/thr_mutex.c:178 error = 140915306 __PRETTY_FUNCTION__ = "safe_mutex_lock" #4 0x08682715 in _sanity ( filename=0x895a87c "/install/mysqlconnc/mysql-connector-c-6.0.2/mysys/my_error.c", lineno=195) at /install/mysqlconnc/mysql-connector-c-6.0.2/mysys/safemalloc.c:520 irem = 0xf2300468 flag = 0 count = 0 #5 0x0868186b in _mymalloc (size=16, filename=0x895a87c "/install/mysqlconnc/mysql-connector-c-6.0.2/mysys/my_error.c", lineno=195, MyFlags=16) at /install/mysqlconnc/mysql-connector-c-6.0.2/mysys/safemalloc.c:130 irem = 0x0 data = 0x0 _db_stack_frame_ = {func = 0x6d617266 <Address 0x6d617266 out of bounds>, file = 0x65685f65 <Address 0x65685f65 out of bounds>, level = 0, prev = 0x0} #6 0x0867e0e1 in my_error_register (errmsgs=0x89a7760, first=2000, last=2058) at /install/mysqlconnc/mysql-connector-c-6.0.2/mysys/my_error.c:194 meh_p = 0x46087568 search_meh_pp = 0x1000 #7 0x08655f7e in init_client_errs () at /install/mysqlconnc/mysql-connector-c-6.0.2/libmysql/errmsg.c:238 No locals. #8 0x08655fe3 in mysql_server_init (argc=0, argv=0x0, groups=0x0) at /install/mysqlconnc/mysql-connector-c-6.0.2/libmysql/libmysql.c:128 result = 0 #9 0x08651fc0 in mysql_init (mysql=0x0) at /install/mysqlconnc/mysql-connector-c-6.0.2/libmysql/client.c:1606Solution:
I put a call to mysql_library_init() before creation of threads and put a call to mysql_library_end() after termination of threads. In each thread, I put a call to mysql_thread_init() at the start of thread function and put a call to mysql_thread_end() at the end of thread function. This solved the problem of crashing.
解决方案Update:
It seems that you need to call mysql_library_init() before
mysql_init():Regarding your original question,
libmysqlclient_r.sois actually a symbolic link tolibmysql.so. You can changelibmysql/CMakeLists.txtto produce a static library (libmysql.a) instead by removing theSHAREDkeyword from the following line:ADD_LIBRARY(libmysql SHARED ${CLIENT_SOURCES} libmysql.def)However, I would recommend (1) trying to run the same code without using threads and see if the problem persists, (2) building and using the debug version of the libraries:
cmake -G "Unix Makefiles" -DCMAKE_BUILD_TYPE=Debug makeThis way you could investigate the problem in more details.
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