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From:<devyani.sapre Date:August 1 2010 10:03am
Subject:Core dump while connection/query/store operation
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Hi All
 
I run multiple threads which query the database. Intermittently I get a dump with the
cause of the error as "Lost conection to MYSQL server during query". My application
connects to the database during the startup, but due to this error, I am now also
checking the connection before making the query and if the connection is not available,
doing a connection and then executing my query. 
 
I haven;t found much help on the web w.r.t this problem. Have tried pretty much of what is
suggested. 
 
1) Changing timout - 8 hrs
2) Ping before query
3) Catching exceptions.
 
Below is one of the core dump I got for actual connection in progress (before trying to
run the query) :
 
#0  0x0000003d24450ceb in ?? () from /usr/lib64/mysql/libmysqlclient.so.15
(gdb) bt
#0  0x0000003d24450ceb in ?? () from /usr/lib64/mysql/libmysqlclient.so.15
#1  0x0000003d24451069 in my_net_read () from /usr/lib64/mysql/libmysqlclient.so.15
#2  0x0000003d2444a862 in cli_safe_read () from /usr/lib64/mysql/libmysqlclient.so.15
#3  0x0000003d2444c25f in mysql_real_connect () from /usr/lib64/mysql/libmysqlclient.so.15
#4  0x00002b849049c44f in mysqlpp::DBDriver::connect (this=0x104926c0, host=0x107e4d58
"127.0.0.1", socket_name=0x0,
    port=0, db=0x104973b8 "SUBSCRIBER", user=0x0, password=0x0) at ./lib/dbdriver.cpp:89
#5  0x00002b8490497d29 in mysqlpp::Connection::connect (this=0x2b84915c9bc0, db=0x104973b8
"SUBSCRIBER",
    server=0x10497458 "127.0.0.1", user=0x0, password=0x0, port=0) at
./lib/connection.cpp:98
#6  0x00002b84913c17ac in UnifiedUserProfileDAO::initializeDB (this=0x10495060) at
UnifiedUserProfileDAO.cpp:31
#7  0x00002b84913c3a73 in UnifiedUserProfileDAO::get_TA_Option (this=0x10495060,
subscriber_id=
        {static npos = 18446744073709551615, _M_dataplus =
{<std::allocator<char>> = {<__gnu_cxx::new_allocator<char>> =
{<No data fields>}, <No data fields>}, _M_p = 0x42577580
"\b\\\001»*"}}) at UnifiedUserProfileDAO.cpp:59
 
What I have observed is that the first time connection during startup is of no use as
after a couple of queries, the connection is lost and before a new query can be run, a
check and reconnect is necessary. Is it expected? Shouldn't one connection be up and
running for sometime.

Kindly help.
 
Thanks
Devyani

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Core dump while connection/query/store operationdevyani.sapre1 Aug