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LP #1043836: Assertion failure with Query_cache on debug build + --debug option

Description

**Reported in Launchpad by Raghavendra D Prabhu last update 23-03-2016 17:31:27

Hit this assertion when running UNIV_DEBUG enabled binary (tested with both 5.5.27 and trunk PS).

===================================================

mysqld: /media/Vone/Percona-Server-5.5.27-rel28.0/sql/sql_cache.cc:1234: void Query_cache::end_of_result(THD*): Assertion `0' failed.

Program received signal SIGABRT, Aborted.
[Switching to Thread 0x7fffc422f700 (LWP 3651)]
0x00007ffff6185fa5 in raise () from /lib/libc.so.6
(gdb) bt
#0 0x00007ffff6185fa5 in raise () from /lib/libc.so.6
#1 0x00007ffff6187428 in abort () from /lib/libc.so.6
#2 0x00007ffff617f002 in __assert_fail_base () from /lib/libc.so.6
#3 0x00007ffff617f0b2 in __assert_fail () from /lib/libc.so.6
bt ful#4 0x0000000000568484 in Query_cache::end_of_result (this=0xf0aec0 <query_cache>, thd=0x24b7cc0) at /media/Vone/Percona-Server-5.5.27-rel28.0/sql/sql_cache.cc:1234
#5 0x000000000059deec in dispatch_command (command=command@entry=COM_QUERY, thd=thd@entry=0x24b7cc0, packet=packet@entry=0x24a80f1 "", packet_length=packet_length@entry=35) at /media/Vone/Percona-Server-5.5.27-rel28.0/sql/sql_parse.cc:1433
#6 0x000000000059e73f in do_command (thd=0x24b7cc0) at /media/Vone/Percona-Server-5.5.27-rel28.0/sql/sql_parse.cc:788
#7 0x0000000000648041 in do_handle_one_connection (thd_arg=thd_arg@entry=0x24afdf0) at /media/Vone/Percona-Server-5.5.27-rel28.0/sql/sql_connect.cc:1484
#8 0x0000000000648137 in handle_one_connection (arg=0x24afdf0) at /media/Vone/Percona-Server-5.5.27-rel28.0/sql/sql_connect.cc:1391
#9 0x00007ffff7bc6e0f in start_thread () from /lib/libpthread.so.0
#10 0x00007ffff623504d in clone () from /lib/libc.so.6
(gdb) bt full
#0 0x00007ffff6185fa5 in raise () from /lib/libc.so.6
No symbol table info available.
#1 0x00007ffff6187428 in abort () from /lib/libc.so.6
No symbol table info available.
#2 0x00007ffff617f002 in __assert_fail_base () from /lib/libc.so.6
No symbol table info available.
#3 0x00007ffff617f0b2 in __assert_fail () from /lib/libc.so.6
No symbol table info available.
#4 0x0000000000568484 in Query_cache::end_of_result (this=0xf0aec0 <query_cache>, thd=0x24b7cc0) at /media/Vone/Percona-Server-5.5.27-rel28.0/sql/sql_cache.cc:1234
header = 0x7fffee007058
last_result_block = <optimized out>
allign_size = <optimized out>
len = <optimized out>
query_cache_tls = 0x24b7ee8
limit_found_rows = 1
_PRETTY_FUNCTION_ = "void Query_cache::end_of_result(THD*)"
_FUNCTION_ = "end_of_result"
query_block = 0x7fffee007000
db_stack_frame = {func = 0xa5e22e "dispatch_command", file = 0xa5e498 "/media/Vone/Percona-Server-5.5.27-rel28.0/sql/sql_parse.cc", level = 2147483651, prev = 0x7fffc422e640}
#5 0x000000000059deec in dispatch_command (command=command@entry=COM_QUERY, thd=thd@entry=0x24b7cc0, packet=packet@entry=0x24a80f1 "", packet_length=packet_length@entry=35) at /media/Vone/Percona-Server-5.5.27-rel28.0/sql/sql_parse.cc:1433
net = 0x24b7ef0
_PRETTY_FUNCTION_ = "bool dispatch_command(enum_server_command, THD*, char*, uint)"
_FUNCTION_ = "dispatch_command"
error = false
db_stack_frame = {func = 0xa5e2d6 "do_command", file = 0xa5e498 "/media/Vone/Percona-Server-5.5.27-rel28.0/sql/sql_parse.cc", level = 2147483650, prev = 0x7fffc422ede0}
#6 0x000000000059e73f in do_command (thd=0x24b7cc0) at /media/Vone/Percona-Server-5.5.27-rel28.0/sql/sql_parse.cc:788
return_value = <optimized out>
packet = 0x24a80f0 "\001"
packet_length = 36
net = 0x24b7ef0
command = COM_QUERY
_PRETTY_FUNCTION_ = "bool do_command(THD*)"
db_stack_frame = {func = 0xb51c91 "?func", file = 0xb51c97 "?file", level = 2147483649, prev = 0x0}
#7 0x0000000000648041 in do_handle_one_connection (thd_arg=thd_arg@entry=0x24afdf0) at /media/Vone/Percona-Server-5.5.27-rel28.0/sql/sql_connect.cc:1484
rc = <optimized out>
create_user = true
thd = 0x24b7cc0
#8 0x0000000000648137 in handle_one_connection (arg=0x24afdf0) at /media/Vone/Percona-Server-5.5.27-rel28.0/sql/sql_connect.cc:1391
thd = 0x24afdf0
#9 0x00007ffff7bc6e0f in start_thread () from /lib/libpthread.so.0
No symbol table info available.
#10 0x00007ffff623504d in clone () from /lib/libc.so.6
No symbol table info available.

================================================================

The my.cnf is http://sprunge.us/FAfX

To reproduce: start mysqld as mysqld --user=mysql --debug (with above my.cnf) and run sysbench or some load, and wait for it to crash on signal 6.

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lpjirasync January 22, 2018 at 5:02 PM

**Comment from Launchpad by: Raghavendra D Prabhu on: 12-09-2012 09:56:57

Ah, yes, I wanted to stress --debug part in the description since the crash is reproduceable only with that.

Regarding why it hits on --debug only, that is interesting.

However,

if (header->result() == 0)
{
DBUG_PRINT("error", ("End of data with no result blocks; "
"Query '%s' removed from cache.", header->query()));
/*
Extra safety: empty result should not happen in the normal call
to this function. In the release version that query should be ignored
and removed from QC.
*/
DBUG_ASSERT(0); ----------------> This is where it is crashing.
free_query(query_block);
unlock();
DBUG_VOID_RETURN;
}

Even though DBUG_PRINT is hit only when --debug is enabled I wonder how it changes the control flow if not present.

lpjirasync January 22, 2018 at 5:01 PM

**Comment from Launchpad by: Alexey Kopytov on: 12-09-2012 09:02:42

It looks like --debug has something to do with it. I could not reproduce it with --debug removed.

lpjirasync January 22, 2018 at 5:01 PM

**Comment from Launchpad by: Alexey Kopytov on: 12-09-2012 08:20:22

No, I spoke too soon. sysbench 0.4 crashes the server just as well with the following command line:

sysbench --test=oltp --oltp-table-size=5000 --num-threads=4 run

lpjirasync January 22, 2018 at 5:01 PM

**Comment from Launchpad by: Alexey Kopytov on: 12-09-2012 08:08:44

Thanks, I can reproduce the crash with both MySQL 5.5 and PS 5.5 and the sysbench command line you have provided. For some reasons, sysbench 0.4 with similar options does not crash the server.

lpjirasync January 22, 2018 at 5:01 PM

**Comment from Launchpad by: Raghavendra D Prabhu on: 11-09-2012 22:50:53

@Alexey,

It didn't take long for crash to happen. Just starting sysbench run crashed it.

Details:

my.cnf – http://sprunge.us/STiQ

Sysbench:

sysbench --test=./oltp.lua --db-driver=mysql --mysql-engine-trx=yes --mysql-table-engine=innodb --mysql-user=root --mysql-password=test --oltp-table-size=5000 --num-threads=4 run

(but any sysbench should crash it I believe).

Tested with both 5.5.27-28.1 and PS 5.5 bzr head.

Done

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Created January 22, 2018 at 5:00 PM
Updated January 22, 2018 at 5:02 PM
Resolved January 22, 2018 at 5:00 PM